Explosion protection - Theory and practice

Explosion protection - Theory and practice | Phoenix Contact

Content Technical and legal bases for explosion protection Directives, standards, and regulations Classification of potentially explosive areas into zones Types of protection Selecting devices Marking of Ex products Installation of systems in potentially explosive areas Designing and installing intrinsically safe circuits Connection technology in the Ex area Installation of electrical devices for signal transmission in the Ex area Glossary 4 8 16 20 28 34 38 40 60 64 68 On the contents: This basic brochure provides an insight into the topic of explosion protection. The document helps planners, installers, and operators of systems in their day-to-day work, but is no substitute for the ongoing study of the relevant legal principles and standards. This brochure explains the physical basics surrounding how explosions form and the technical measures that can be taken to prevent them. Furthermore, the globally relevant legal bases and standards as well as the European directives and North American standards for electrical explosion protection are described. Moreover, the document provides assistance to system operators when installing systems in potentially explosive areas. Here, the focus is on the design and installation of intrinsically safe circuits. Further information on explosion protection: Simply type the web code into the search field on our website.  Web code: #2267 Phoenix Contact 3

1 Technical and legal bases for explosion protection The safety of people and production processes as well as a clean environment are important corporate goals worldwide. The prerequisite for achieving these goals is to be aware of how explosions occur wherever combustible materials, oxygen, and sources of ignition can come together, and how to avoid them. 1.1 Formation and prevention of explosions Combustion is an oxidation reaction in which energy is released. Whereas the energy during a fire is released slowly, when large amounts of energy are released suddenly it is referred to as an explosion. As the speed with which the combustion spreads increases, the process is referred to as fast combustion, then deflagration and, in extreme cases, detonation, in this order. In the case of complete combustion, the damage caused increases significantly with the propagation velocity. Orders of magnitude of propagation: • Fast combustion cm/s • Deflagration m/s • Detonation km/s An explosion occurs when there is a combination of a combustible material, oxygen, and a source of ignition. If any one component is missing, no exothermic reaction occurs. Explosive atmospheres Mixture of combustible material and oxygen within the explosive limits Combustible material Combustible gases (mists, vapors) and combustible dusts Oxygen For example, oxygen contained in air Explosion Simultaneous presence of combustible material, oxygen, and source of ignition 4 Phoenix Contact Sources of ignition of electrical devices For example, hot surfaces or energy/sparks

1.1.1 Upper and lower explosive limits In the case of gases, the ratio of concentrations determines whether an explosion is possible. The mixture can only be ignited if the concentration of the material in air is between the lower explosive limit (LEL) and the upper explosive limit (UEL). Some chemically non-resistant materials (e.g., acetylene, ethylene oxide) can also undergo exothermic reactions without oxygen through self-decomposition. The upper explosive limit (UEL) changes to 100 percent by volume. The explosion range of a material expands as the pressure and temperature rise. Similar specifications as those defined for gases can also be made for dusts even though the explosive limits do not have the same meaning here. Clouds of dust are generally heterogeneous and the concentration within the same cloud fluctuates greatly. A lower flammability limit (of approximately 20 ... 60 g/m3) Explosive limits of hydrogen and an upper flammability limit (of approximately 2 ... 6 kg/m3) can be determined for dust. Due to different standards and the measuring procedures described therein, slightly different values may occur when determining the explosive limits. The limit values listed below are based on IEC/EN 60079-20. Too weak Too strong Lower explosive limit Upper explosive limit Hydrogen in air (volume percent) 0 4 50 77 100 Explosive atmosphere Examples of gases under normal pressure Acetone Acetylene Ammonia Butane Diesel fuel Carbon monoxide Methane Gasoline Carbon disulfide Hydrogen 13 2.5 2.3 15.5 33.6 1.4 9.3 0.6 6.5 10.9 4.4 16.5 0.6 8 0.6 4 78 100 76 77 60 Flammable materials in air (volume percent) 0 50 100 Phoenix Contact 5

1.1.2 Overview of effective sources of ignition Source of ignition Examples of causes Sparks Electric arcs Hot surfaces Mechanically created sparks (e.g., caused by friction, impact, or abrasion processes), electric sparks. The operator is obligated to implement measures for explosion protection in a specified order. Short circuit, switching operations. Heater, metal-cutting production, heating up during operation. Flames and hot gases Combustion reactions, flying sparks during welding. Electrical systems Opening/closing of contacts, loose contact. A protective extra-low voltage (U <50 V) is not an explosion protection measure. Low voltages can still generate sufficient energy to ignite a potentially explosive atmosphere. Static electricity Discharge of charged, separately arranged conductive parts – as with many plastics, for example. Electrical compensating currents, cathodic corrosion protection Reverse currents from generators, short circuit to exposed conductive part/ground fault in the event of errors, induction. Electromagnetic waves in the range of 3 x 1,011 … 3 x 1,015 Hz Laser beam for distance measurement, especially for focusing. High frequency 104 … 3 x 1,012 Hz Wireless signals, industrial high-frequency generators for heating, drying or cutting. Lightning strike Atmospheric weather disturbances. Ionizing radiation X-ray machine, radioactive material, absorption of energy leads to heating up. Ultrasound Absorption of energy in solid/liquid materials leads to heating up. Adiabatic compression and shock waves Sudden opening of valves. Exothermic reactions Chemical reaction leads to heating up. 6 Phoenix Contact

1.1.3 Explosion protection measures The operator is obligated to implement measures for explosion protection in a specified order. As a rule, priority must be given to measures to avoid potentially explosive atmospheres. It is therefore necessary to consider first whether and to what extent these measures can be applied in a meaningful way. If a satisfactory solution cannot be found, measures must be taken to avoid an ignition source. If this is not sufficient, design explosion protection measures are required – if necessary, even suitable combinations of the measures described. While primary explosion protection prevents the presence of the explosive atmosphere, with secondary explosion protection an explosion is safely prevented by avoiding effective ignition sources by design. Depending on the application, there are different types of protection with different protection principles for secondary explosion protection. There is also tertiary explosion protection. This involves design measures that reduce the consequences of an explosion to an acceptable level. Order explosion protection measures 1. Primary explosion protection Prevent formation of hazardous explosive atmosphere. • Avoid combustible materials (replacement technologies) • Inertization (addition of nitrogen) • Ventilation and air supply • … 2. Secondary explosion protection 3. Constructive explosion protection Prevent ignition of hazardous explosive atmosphere. • Electrical explosion protection Limit impact of an explosion to a safe level • Pressure-resistant design • Pressure relief and pressure compensation equipment (burst washers) Phoenix Contact 7

2 Directives, standards, and regulations Special safety measures are required for the operation of systems and machines in areas with explosive atmospheres. The internationally applicable requirements are listed in the most important directives and standards for the global market. 2.1 Explosion protection in the European Union – ATEX directives The ATEX Directive governs the harmonization of legal provisions in the member states for devices and protective systems in terms of ensuring correct use in potentially explosive areas. The term ATEX is derived from the French words “ATmosphère EXplosible”. In order to address the issue of explosion protection, the European Union introduced ATEX Directive 2014/34/EU for manufacturers and Directive 1999/92/EC for operators. These directives were then translated into the national legislation of the different member states – in Germany, for example, into the manufacturer directive with the 11th Product Safety Ordinance (11th ProdSV), also called the Explosion Protection Product Ordinance (ExVO), and into the operator directive with the German Ordinance on Industrial Safety and Health (BetrSichV) and the Hazardous Materials Ordinance (GefStoffV). Target group Directive Common designation Manufacturers 2014/34/EU ATEX 114 Operators 1999/92/EC ATEX 137 8 Phoenix Contact Equipment group and category in accordance with ATEX Directive 2014/34/EU In order to determine the appropriate procedure to be used for conformity assessment, the manufacturer must first decide which equipment group and category the product belongs to, based on its intended use (more information starting on page 9). Equipment group I: Equipment for use in underground mining and the connected surface installations which are endangered by firedamp (methane) or combustible dusts. Equipment group II: Equipment for use in all other areas which might be endangered by an explosive atmosphere. Equipment categories are assigned to the equipment groups in Directive 2014/34/EU. Categories M1 and M2 are determined for equipment group I. Three categories – 1, 2, and 3 – are defined in equipment group II. The category is used to determine the connection with the zones in operator directive 1999/92/EC. Equipment group II: surface installations Potentially explosive areas Equipment group I: underground mining Areas susceptible to firedamp = coal mining

Requirements of equipment groups and categories Equipment group Equipment category Degree of protection Protection guarantee Operating conditions I I II II II M1 M2 1 2 3 Very high degree of safety Two independent protective measures. Safe if two errors occur independently of one another. For reasons of safety, it must be possible to continue operating a device even if the atmosphere is potentially explosive. High degree of safety In normal operation, protective measures remain effective even under difficult conditions. It must be possible to switch off these devices if a potentially explosive atmosphere occurs. Very high High Two independent protective measures. Safe if two errors occur independently of one another. Devices can still be used in zones 0, 1, 2 (G)1), and 20, 21, 22 (D)2) and continue to be operated. Safe in normal operation and if common faults occur. Devices can still be used in zones 1, 2 (G)1), and 21, 22 (D)2) and continue to be operated. Normal Safe in normal operation. 1) (G) = gas2) (D) = dust Devices can still be used in zones 2 (G)1) and 22 (D)2) and continue to be operated. Conformity assessment Before a product can be placed on the market in the European Union, every manufacturer must conduct a conformity assessment procedure. There are several so-called Modules that the manufacturer can use for this depending on the group and category the product is classified into. A combination of Modules B and D is generally used for Category 1 and 2 electrical devices. The identification number of the notified body that is monitoring the production process is then added after the c marking, for example, c 0344. In the case of individual testing (Module G – unit verification), the identification number of the notified body that conducted the individual testing must be appended to the c marking. Module A (internal control of production) is used for Category 3 electrical devices. In this case, a Notified Body identification number may not be used. Group II Group I Category 1 M1 M2 Category 2 Category 3 EU type test Module B 1) Examination 1) QA production QA product Internal production control Individual testing Module D Module E c 0344 c 0344 Module A c 0344 Module G c 0344 1) Optional Conformity assessment in accordance with Directive 2014/34/EU for electrical equipment Phoenix Contact 9

Notified body Notified bodies (previously named bodies) are private testing institutions that have been named by the EU member states to conduct certain parts of a conformity assessment procedure. For example, when Module B is being used in accordance with Directive 2014/34/EU, the notified body Testing institute PTB DEKRA Testing and Certification GmbH TÜV Nord IBExU BAM INERIS LCIE LOM DEKRA Certification B.V. CESI UL DEMKO NEMKO tests the technical design of the product and certifies it by issuing an EU Type test certificate stating that it has met the applicable requirements. An up-to-date overview of the notified bodies can be found in the Nando Information System of the European Commission. Country Germany Germany Germany Germany Germany France France Spain Netherlands Italy Denmark Norway Identification 0102 0158 0044 0637 0589 0080 0081 0163 0344 0722 0539 0470 2.2 Explosion protection in North America – NEC and CEC In the USA, the requirements governing installation of electrical devices are described in the National Electrical Code (NEC) NFPA 70, and in Canada in the Canadian Electrical Code (CEC) CSA C22.1. In addition to the requirements for standard use (ordinary locations), they also include requirements for use in potentially explosive areas (hazardous locations). The fundamental component in this case is an approval, that is, a design-based assessment of the product performed by a recognized testing institute (National Recognized Testing Laboratory in the USA or a company accredited by the Standard Council of Canada in Canada). 10 Phoenix Contact Devices may be subdivided based on the Class/Division system, as it is known, or based on the Class/Zone system, which is in turn based on international standards. Since both systems are used, care must be taken when choosing devices to ensure that the approval matches the application. Devices that are approved under both systems spare the user the need for this consideration. Well-known NRTLs include: • Underwriter Laboratories Inc. (UL) • CSA Group Testing and Certification Inc (CSA) • FM Approvals LLC (FM)

National Electrical Code (NEC) in USA Item Content 500 501 502 503 504 505 506 General requirements for Divisions of Class I, II, and III Requirements for Divisions of Class I Requirements for Divisions of Class II Requirements for Divisions of Class III Requirements for Divisions of Class I, II, and III in relation to intrinsic safety (IS) General and special requirements for zones 0, 1, and 2 General and special requirements for zones 20, 21, and 22 Canadian Electrical Code (CEC) in Canada Item 18-000 18-090 18-100 18-200 18-300 Content General requirements for Class I/zone and Class II and III/Divisions Requirements for zone 0 of Class I Requirements for zone 1 and 2 of Class II Requirements for Divisions of Class II Requirements for Divisions of Class III Appendix J General and special requirements for divisions of Class I 2.3 Worldwide explosion protection – IECEx IECEx is an international method for certifying equipment that is used in potentially explosive areas. The aim of the IECEx schema is to harmonize national and international Ex standards. This simplifies the global trade in equipment for potentially explosive applications without compromising on the high safety level of the ATEX directive. The equipment certified in accordance with IECEx is recognized worldwide by the internationally uniform standards, tests, and test marks. Based on existing IECEx approvals, national approvals such as CCC for China, INMETRO for Brazil or Kosha (KC) for Korea can be obtained more easily. 2.4 Standardization – electrical explosion protection for manufacturers Manufacturers can use a range of standards when assessing their products during and after development. The ATEX Directive 2014/34/EU stipulates compliance with basic safety and health requirements. This is achieved through the use of the harmonized standards published in the Official Journal of the European Union (EN standards), for example. As already mentioned under 2.3, the IECEx standards published by the International Electrotechnical Commission (IEC) form the basis for almost all of the harmonized standards, as well as an ever-increasing number of the standards in use from various countries. The IEC 60079 series of standards deals with electrical explosion protection for gas and dust atmospheres worldwide. In addition, there are also national standards and standards specific to testing institutions, such as certain UL standards. Just as there are standards regarding gas explosion protection, there are also standards for dust explosion protection. Phoenix Contact 11

Standards for electrical equipment in areas with a danger of gas explosions Type of protection Symbol NEC reference CEC reference Principle General requirements Intrinsic safety Increased safety Non-hazardous to ignite Explosion-proof Flameproof enclosure Molded encapsulation Liquid immersion Sand filling Pressurized enclosure Type of protection “n” Intrinsically safe systems Optical radiation range Ex AEx i IS Ex e AEx e NI XP Ex d AEx d Ex m AEx m Ex o AEx o Ex q AEx q Ex p AEx p Type X, Y, Z Ex n AEx n Ex i Ex op AEx op Article 505 Article 504 Article 505 Section 18 Section J Section 18 Basis for types of protection Energy limitation Constructional measures through spacing and dimensioning Article 501 Section J Constructional measures through spacing and energy limitation Article 501 Section J Constructional measures through housing Article 505 Article 505 Article 505 Article 505 Article 505 Article 501 Article 505 Article 505 Section 18 Section 18 Section 18 Section 18 Section 18 Section J Section 18 Constructional measures through housing Exclusion of an explosive atmosphere Exclusion of an explosive atmosphere Exclusion of an explosive atmosphere Exclusion of an explosive atmosphere Better industrial quality Energy limitation in interconnected intrinsically safe circuits Section 18 Limitation of radiation power IS = Devices with intrinsically safe circuits NI = non-incendive equipment and non-incendive field circuits XP = Explosion-proof type X, Y, Z = pressurized enclosure Standards for electrical equipment in areas with a danger of dust explosions Type of protection Symbol NEC reference CEC reference Principle General requirements Basis for types of protection Protection provided by housing Intrinsic safety Pressurized enclosure Molded encapsulation Optical radiation range Non-hazardous to ignite Ex t AEx t DIP DT Ex i AEx i IS Ex p AEx p Type X, Y, Z Ex m AEx m Ex op AEx op NI Article 506 Article 502 Article 502 Article 505 Article 504 Article 505 Article 502 Article 505 Section 18 Section J Section J Section 18 Section J Section 18 Section J Section 18 Protection through housing design Energy limitation Exclusion of an explosive atmosphere Exclusion of an explosive atmosphere Limitation of radiation power Article 502 Section J Energy limitation DT = Dust-proof housing DIP = Dust explosion-protected IS = Devices with intrinsically safe circuits NI = Non-incendiary equipment and non-incendiary type X, Y, Z = pressurized enclosure 12 Phoenix Contact

EN standard IEC standard USA, Division (NEC 500) USA, zone (NEC 505) Canada, division Canada, zone EN IEC 60079-0 IEC 60079-0 EN 60079-11 IEC 6079-11 EN IEC 60079-7 IEC 60079-7 EN 60079-1 IEC 60079-1 EN 60079-18 IEC 60079-18 EN 60079-6 IEC 60079-6 EN 60079-5 IEC 60079-5 EN IEC 60079-2 IEC 60079-2 EN IEC 60079-15 IEC 60079-15 EN IEC 60079-25 IEC 60079-25 EN 60079-28 IEC 60079-28 UL 913 UL 121201 UL 1203 NFPA 496 UL 60079-0 UL 60079-11 UL 60079-7 UL 60079-1 UL 60079-18 UL 60079-6 UL 60079-5 UL 60079-2 UL 60079-15 UL 60079-28 CSA C22.2 No. 157 CSA C22.2 No. 213 CSA C22.2 No. 30 NFPA 496 CSA C22.2 No. 60079-0 CSA C22.2 No. 60079-11 CSA C22.2 No. 60079-7 CSA C22.2 No. 60079-1 CSA C22.2 No. 60079-18 CSA C22.2 No. 60079-6 CSA C22.2 No. 60079-5 CSA C22.2 No. 60079-2 CSA C22.2 No. 60079-15 CSA C22.2 No. 60079-28 EN standard IEC standard USA, division USA, zone Canada, division Canada, zone EN IEC 60079-0 IEC 60079-0 EN 60079-31 IEC 60079-31 EN 60079-11 IEC 60079-11 EN IEC 60079-2 IEC 60079-2 EN 60079-18 IEC 60079-18 EN 60079-28 IEC 60079-28 UL 1203 UL 121201 UL 913 NFPA 496 UL 60079-0 UL 60079-31 UL 60079-11 UL 60079-2 UL 60079-18 UL 60079-28 CSA C22.2 No. 25 CSA C22.2 No. 213 CSA C22.2 No. 157 NFPA 496 CSA C22.2 No. 60079-0 CSA C22.2 No. 60079-31 CSA C22.2 No. 60079-11 CSA C22.2 No. 60079-2 CSA C22.2 No. 60079-18 CSA C22.2 No. 60079-28 UL 121201 CSA C22.2 No. 213 Phoenix Contact 13

2.5 Standardization – mechanical explosion protection for manufacturers ATEX Directive 2014/34/EU contains harmonized requirements for non- electrical devices, including use in areas with a danger of dust explosions. There are standards for non-electrical devices, just as there are for electrical devices. Type of protection Symbol EN standard Basic method and requirements Flameproof enclosure Pressurized enclosure Constructional safety Control of ignition source Liquid immersion d p c b k EN ISO 80079-36 EN 60079-1 EN 60079-2 EN ISO 80079-37 EN ISO 80079-37 EN ISO 80079-37 IEC standard ISO IEC 80079-36 IEC 60079-1 IEC 60079-2 ISO 80079-37 ISO 80079-37 ISO 80079-37 2.6 Standardization – explosion protection for system operators Directive 1999/92/EC requires operators of process engineering systems to ensure that the systems are protected against explosion. The requirements to be met with regard to planning, installation, and operation are specified in the EN and IEC standards. Designation Explosion protection Part 1: Basic concepts and methodology Explosive atmospheres Part 10.1: Classification of areas – explosive gas atmospheres Part 10.2: Classification of areas – explosive dust atmospheres Potentially explosive areas Part 14: Configuration, selection, and installation of electrical systems Potentially explosive areas Part 17: Testing and maintenance of electrical systems Potentially explosive areas Part 19: Equipment repair, overhaul, and reclamation EN standard IEC standard EN 11271 EN 60079-10-1 EN 60079-10-2 IEC 60079-10-1 IEC 60079-10-2 EN 60079-14 IEC 60079-14 EN 60079-17 IEC 60079-17 EN 60079-19 IEC 60079-19 14 Phoenix Contact

3 Classification of potentially explosive areas into zones Potentially explosive areas are divided into zones in accordance with to ATEX and IECEx. In the USA, there is also the division concept (NEC 500) in addition to the zone concept (NEC 505). Zone classification is the responsibility of the plant operator. 3.1 Zone classification in accordance with ATEX and IECEx The zone division is regulated in Europe via the ATEX Directive 1999/92/EC (Workplace Directive). Furthermore, there are standards for zone classification in IEC/EN°60079-10. The European Committee for Standardization (CEN) has also created standard EN 11271. EN 11271 contains basic information on explosion protection and provides support for both ATEX Directives (2014/34/EU and 1999/92/EC). In addition, there is country-specific assistance for zone classification, such as the explosion protection rules of the German Federal Employers’ Association for Chemical Industry. Explosive areas for gases and dusts are likewise classified into zones: Zone classification for gases in accordance with ATEX Directive 1999/EC/92 and IEC/EN 60079-10-1 Zone classification Type and duration of the danger Zone 0 Zone 1 Zone 2 Area in which an explosive atmosphere consisting of a mixture of air and combustible materials in the form of gas, vapor, or mist is present continuously or for long periods or frequently. Area in which an explosive atmosphere consisting of a mixture of air and combustible materials in the form of gas, vapor, or mist is likely to occur in normal operation occasionally. Area in which an explosive atmosphere consisting of a mixture of air and combustible materials in the form of gas, vapor, or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only. Zone classification for dusts in accordance with ATEX Directive 1999/EC/92 and IEC/EN 60079-10-2 Zone classification Type and duration of the danger Zone 20 Zone 21 Zone 22 Area in which an explosive atmosphere in the form of an airborne cloud of combustible dust is present continuously or for long periods or frequently present. Area in which an explosive atmosphere in the form of an airborne cloud of combustible dust is likely to occur in normal operation occasionally. Area in which an explosive atmosphere in the form of an airborne cloud of combustible dust is not likely to occur in normal operation but, if it does occur, will persist for a short period only. 16 Phoenix Contact

Zone classification for gas using the example of a storage tank for flammable liquids Valve Zone 1 Zone 0 Zone 2 Drain Zone 1 Zone 0 • Inside the tank above the combustible Zone 1 • Area (e.g., 2 m radius) around the inlet Zone 2 • Area around the tank up to the protective liquid and outlet valve • Sinks in which flammable gases that are heavier than air can accumulate wall 3.2 Zone or division classification in accordance with NEC and CEC In the National Electrical Code (NEC), explosive areas in the USA and in Europe are assigned according to their danger. In Canada, the procedure comparable and based on the Canadian Electrical Code (CEC). However, for a long time, only a division of potentially explosive areas into two classes or divisions was common in the USA in accordance with Article 500 of the NEC. It was only with Article 505 of the NEC from 1996 that the international classification of potentially explosive areas into three zones for gases/liquids and dusts was also introduced in the USA. Both legal standards (Article 500 and Article 505) exist side by side. As already mentioned, Article 500 of the NEC only recognizes two areas with regard to the frequency of occurrence, whereby a distinction is only made between the explosion hazard in normal operation (Division I) and in the event of malfunctions or defects (Division II). However, when defining potentially explosive areas, it relies on a different subdivision by focusing on the type of hazardous source (gas, liquid, dust, etc.) and the severity of the explosion hazard. The various areas (divisions) are therefore divided into further classes (class) and groups (groups). Phoenix Contact 17

Simplified assignment diagram for zones and division concepts Explosive area IEC/EN Zone 0 USA: NEC 505 Zone 0 USA: NEC 500 Division 1 Zone 1 Zone 1 Zone 2 Zone 2 Division 2 Explosive material Class Group Explosive material Class Group Gas/vapor or liquid Dust Fibers I II III A, B, C, D Gas/vapor or liquid E, F, G Dust –– Fibers I II III A, B, C, D F, G –– This simplified assignment scheme can only be regarded as a rough approximation of the possibilities. Any conversion must be verified on a case-by-case basis. This applies in particular to electrical equipment for Division 2, which can often only be used in zone 2 without additional testing and certification. Divisional divisions into areas and groups in accordance with NEC 500 Groups (typical material) Group A (acetylene) Group B (hydrogen) Group C (ethylene) Group D (propane) Group E (metal dust) Group F (coal dust) Group G (grain dust) No subgroups Area Class I (gases and vapors) Class II (dusts) Class III (fibers) 18 Phoenix Contact

3.3 Overview of divisions and classes in accordance with NEC 500 Classification Explosive atmospheres Type of danger Class I, Division 1 Class I, Division 2 Class II, Division 1 Class II, Division 2 Class III, Division 1 Class III, Division 2 Gas, liquid, and vapor Gas, liquid, and vapor Incendiary concentrations of inflammable gases, vapors or liquids may be present constantly or temporarily under normal operating conditions. Incendiary concentrations of inflammable gases, vapors or liquids do not usually occur under normal operating conditions. Dust Dust Fibers Fibers Incendiary concentrations of combustible dust may be present constantly or temporarily under normal operating conditions. Incendiary concentrations of combustible dust do not usually occur under normal operating conditions. Areas in which readily flammable fibers are processed or transported. Areas in which readily flammable fibers are stored or transported. Phoenix Contact 19

4 Types of protection Depending on the application, there are different types of protection with different protection principles for secondary explosion protection. What they all have in common is that the ignition of an explosive atmosphere is avoided. 4.1 Overview of essential types of protection inside the housing, during operation. The housing does not rule out the ingress of gases. For increased safety, the IP degree of protection can be reduced to IP20, for example, if additional protective measures are taken. Some of these must be taken into consideration during installation. Altering cable and line entries in type of protection Ex d, for example, by removing rust with a wire brush, is not permitted. Doing this could change the gap, thus destroying the protection principle. The manufacturer’s specifications must be strictly observed. 4.1.1 Increased safety Ex e In increased safety protection, voltages up to 11 kV can be brought into the potentially explosive area. Increased safety is particularly suitable for supplying motors, lamps, and transformers. The protection principle is based on constructional measures. Air clearances and creepage distances are determined for the live parts and divided into voltage levels. This prevents electrical sparks. In addition, IP54 degree of protection (EN 60529) must be satisfied at the very least. Limiting the surface temperature ensures that the explosive atmosphere cannot be ignited at any point, not even 4.1.2 Flameproof enclosure Ex d In flameproof enclosure protection, an explosion is prevented from spreading by the housing design. An explosion that occurs inside is not able to ignite the explosive atmosphere surrounding the housing. This leads to very robust housings. The housings have covers and entry points, for example, for cables and lines. The maximum permitted gap that is present is dimensioned in such a way that it prevents the explosion from spreading from inside the housing to the surrounding explosive atmosphere. 20 Phoenix Contact

4.1.3 Molded encapsulation, sand filling, or oil immersion Ex m, Ex q, Ex o The principle of molded encapsulation, sand filling, and oil immersion protection types of protection is to surround possible sources of ignition in an item of electrical equipment with the medium of a molding compound, sand, or oil. This prevents the explosive atmosphere from igniting. Voltages from 10 … 11 kV can also be used in these types of protection. Ex m Ex o Ex q 4.1.4 Pressurized enclosure Ex p Pressurized enclosure protection describes methods that use overpressure to prevent an explosive atmosphere from entering into housings or the control room. The ambient pressure surrounding the housing is always lower than the pressure inside. Three forms of pressurized enclosure are possible (see table). In the case of static overpressure, the housing must be hermetically sealed. There is no loss of pressure. More common, however, are methods in which the overpressure is maintained by compensating the leakage losses or by continuous purging. The overpressure is usually created by simple compressed air. Ex p protection requires a monitoring unit that reliably switches off the electrical equipment inside the housing as soon as sufficient overpressure is no longer present. The monitoring unit must be designed in a different Possibilities of pressurized enclosure Pressurized enclosure Static type of protection so that it can also be operated without overpressure. Items of equipment can be operated inside without taking explosion protection into account. The surface temperature of the items of equipment must not ignite the penetrating potentially explosive atmosphere once the overpressure has dropped. If operational conditions dictate that a device or component inside the housing must not be switched off, it must be protected against explosion with a different type of protection. Compensation of the leakage losses Continuous purging Compressed air Without correction Compensation of the leakage losses Continuous correction Operating states --- Pre-purging phase: The housing is purged and any explosive atmosphere that is present is removed from the housing. Operating phase: The overpressure in the housing is monitored. If it decreases, the electrical equipment inside the housing is switched off. Phoenix Contact 21

4.1.5 Ex i intrinsic safety protection connected to the intrinsically safe circuits. Energy may also be stored in the form of capacitances or inductances within the intrinsically safe circuit. This must also be taken into consideration when examining the intrinsically safe circuit. Explosive atmospheres Io L R Uo C U Intrinsic safety protection, as opposed to other types of protection (such as increased safety), refers not only to individual items of equipment, but to the entire circuit. A circuit is described as intrinsically safe if the current and voltage are limited to such an extent that no spark or thermal effect can cause a potentially explosive atmosphere to ignite. The voltage is limited in order to keep the energy of the spark below the ignition energy of the surrounding gas. The thermal effect, that is, excessively hot surfaces, is prevented by limiting the current. This is also true of the sensors 4.1.6 Ex n protection included in the current edition IEC/EN 60079-15:2017. It has already been adopted into IEC 60079-7:2015 as safety level “ec”. The n type of protection can be described as an improved industrial quality that is designed for normal operation. An additional error consideration is not carried out and therefore the type of protection n is only suitable for use in zone 2 or zone 22. This can only be used in device group II (ATEX) or in groups II and III (IECEx). The manufacturer specifies the technical data for normal operation. In the case of type of protection n, a distinction is made between five different versions, which can be derived in part from the familiar types of protection: increased safety, intrinsic safety, flameproof enclosure, pressurized enclosure, and molded encapsulation. The type of protection n includes the types of protection nA, nC, and nR. Since the IEC 60079-15:2005 IEC 60079-15:2010 type of protection, the nZ has been included in the protection level pzc in the IEC 60079-2:2014 type of protection. nL has been included in the protection level ic in the standard IEC 60079-11:2006. nA type of protection is no longer Subdivision of type of protection n in accordance with IEC/EN 60079 Abbreviation Significance Comparable with … Method Subdivision of the groups in accordance with IECEx A C R Non-sparking Ex e Occurrence of electric arcs, sparks, or hot surfaces is minimized. As of IEC 60079-0:2007, subdivided into IIA, IIB, IIC Sparking equipment To some extent, Ex d and Ex m Enclosed switching device, nonflammable components, hermetically sealed, sealed, or encapsulated installations. IIA, IIB, IIC, and IEC 60079-0:2007 Restricted breathing housings --- Ingress of explosive gases is limited. As of IEC 60079-0:2007, subdivided into IIA, IIB, IIC 22 Phoenix Contact

4.2 Protection types and their applications Types of protection for electrical equipment in areas with a danger of gas explosions Type of protection Protection principle EN/IEC Zone Application da d, db dc px py pz q ob oc eb ec ia ib ic Flameproof enclosure Prevention of explosion spreading Pressurized enclosure Exclusion of an explosive atmosphere EN 60079-1 IEC 60079-1 EN 60079-2 IEC 60079-2 Sand filling Prevent spark propagation and increased temperatures EN 60079-5 IEC 60079-5 Oil immersion Exclusion of an explosive atmosphere EN 60079-6 IEC 60079-6 Increased safety Prevent spark propagation and increased temperatures EN 60079-7 IEC 60079-7 Intrinsic safety Energy limitation Intrinsically safe fieldbus systems (FISCO) EN 60079-11 IEC 60079-11 EN 60079-25 IEC 60079-25 nA Non-sparking equipment Prevent sparks, comparable with Ex ec EN 60079-15 IEC 60079-15 nC Sparking equipment Sealed or hermetically sealed equipment EN 60079-15 IEC 60079-15 Restricted breathing housing Protection provided by housing Molded encapsulation Exclusion of an explosive atmosphere EN 60079-15 IEC 60079-15 EN 60079-18 IEC 60079-18 nR ma mb mc op 0 1 2 1 2 1 2 1 2 1 2 0 1 2 0 1 2 2 2 2 0 1 2 Switching, control, and signaling devices, controllers, motors, power electronics Control cabinets, motors, measuring and analysis devices, computers Transformers, relays, capacitors Transformers, relays, startup controls, switching devices Branch and connection boxes, housing, motors, terminal blocks, electrical devices Measurement and control technology, sensors, actuators, instrumentation Electrical equipment for normal industrial applications Electrical equipment for normal industrial applications Electrical equipment for normal industrial applications Coils of relays and motors, electronics, solenoid valves, connection systems Optoelectronic devices Phoenix Contact 23 op is – inherently safe optical radiation op pr – protected optical radiation op sh – optical systems with interlock Limiting or preventing the transmission of energy from optical radiation EN 60079-28 IEC 60079-28 0 or 1 or 2 1 or 2 0 or 1 or 2

Electrical equipment in areas with a danger of dust explosions Type of protection Protection principle EN/IEC Zone Application ta tb tc pxb pyb pzc ia ib ic ma mb mc Protection provided by housing Exclusion of an explosive atmosphere Pressurized enclosure Exclusion of an explosive atmosphere Intrinsic safety Energy limitation Molded encapsulation Exclusion of an explosive atmosphere EN 60079-31 IEC 60079-31 EN 60079-2 IEC 60079-2 EN 60079-11 IEC 60079-11 EN 60079-18 IEC 60079-18 20 21 22 21 21 22 20 21 22 20 21 22 Switching, command, and signaling devices, lamps, branch and connection boxes, housings Control cabinets, motors, measuring and analysis devices Measurement and control technology, sensors, actuators, instrumentation Coils and relays of motors, electronics, and connection systems 4.3 Intrinsic safety protection 4.3.1 Principle Intrinsic safety (Ex i) type of protection has established itself worldwide in the field of measurement and control technology in systems with potentially explosive areas. Intrinsically safe circuits are generally composed of the following elements: • Intrinsically safe equipment, that is., a load installed in the Ex area, such as an Ex i temperature transmitter • associated equipment, which involves a source in the non-Ex area (Ex i isolator) • Connecting cable between intrinsically safe and associated equipment The protection principle behind the Ex bi type of protection is based on limiting the energy that is conducted to the potentially explosive area and is stored there. This means that the energy from any potential spark must always be less than the minimum ignition energy of the surrounding potentially explosive atmosphere. As opposed to all the other types of protection, Ex i refers not only to a single item of equipment but also to the entire intrinsically safe circuit, in accordance with IEC/EN 60079-11. 24 Phoenix Contact Potentially explosive area Io Uo L R C U Basic intrinsically safe circuit diagram The voltage is limited in order to keep the energy of the spark below the ignition energy of the surrounding gas. The thermal effect, that is, excessively hot surfaces, is prevented by limiting the current.

Ignition energies of typical gases Group Typical gas I IIA IIB IIC Methane Propane Ethylene Hydrogen Ignition energy/μJ 280 >180 60 … 180 <60 Voltage and current limitation When limiting voltage and current, the following applies for the maximum power: Io=Imax R Uo Uo=Uz Basic circuit diagram for limiting voltage and current The Zener diode becomes conductive at a defined voltage level. This limits the voltage Uo in the potentially explosive area. A resistor connected in series limits the maximum current Io. Imax = Io = Uo R Po = 2 Uo 4R The maximum permissible values are determined by the ignition limit curves specified in standard IEC/EN 60079-11. The ignition limit curves were determined using a spark tester, as described in Appendix B of IEC/EN 60079-11. The ignition limit curves contain specifications for gas groups I and II as well as dust group III. Group II (gases) is further subdivided into IIA, IIB, and IIC, depending on the ignition energy. Group III (dusts) is divided accordingly into IIIA, IIIB, and IIIC. Potentially explosive area Safe area 4.3.2 Intrinsically safe circuit An intrinsically safe circuit consists of at least one item of intrinsically safe equipment and one item of associated equipment and connecting cables. The circuits of the electrical equipment satisfy the requirements of intrinsic safety. Intrinsically safe equipment may only be connected to non- intrinsically safe circuits via associated equipment. Associated equipment has both intrinsically safe circuits and non- intrinsically safe circuits. The circuits are isolated using Zener barriers or electrical isolators. Intrinsically safe equipment and intrinsically safe parts of associated equipment are classed in accordance with IEC/EN 60079-11 in safety levels ia, ib, and ic. Intrinsically safe equipment (field device) Associated equipment, e.g., Ex i repeater power supply Example of an intrinsically safe circuit Phoenix Contact 25

4.3.3 Safety level in accordance with IEC/EN 60079-11 Safety level ia, ib or ic defines whether protection is maintained with two faults or one fault in the protective circuit, or whether no protection is provided in the event of a fault. Intrinsic safety is based on fault monitoring in order to rule out an explosion hazard. This does not, however, provide any conclusions as to operational safety. This means that a total functional failure of the equipment may be permissible from the point of view of explosion protection. Electrical equipment can be used right up to zone 0 in accordance with the safety level. Associated equipment is installed in the safe area. Only the intrinsically safe circuits are routed into the potentially explosive area in accordance with the safety level. Associated equipment can always be designed with a different type of protection in order for it to be installed in zone 2 or perhaps even in zone 1. Safety level Fault monitoring Permissible zones ia ib ic Under normal operating conditions, not able to cause ignition if any combination of two faults occurs. 0, 1, 2 Under normal operating conditions, not able to cause ignition if one fault occurs. Under normal operating conditions, device is not able to cause ignition. 1, 2 2 4.3.4 Associated equipment with or without electrical isolation For intrinsically safe circuits in zone 0, the standard IEC/EN 60079-14 Section 12.3 recommends the preferential use of protection level “ia” in conjunction with electrical isolation. Connection to the Ex area Connection to safe area Connection to the Ex area Connection to safe area Without electrical isolation: Ex i Zener barrier With electrical isolation: Ex i signal conditioner 26 Phoenix Contact

4.3.5 Simple electrical equipment Simple electrical equipment does not require approval; however, it must be assigned to a temperature class and conform with any other applicable requirements of IEC/EN 60079-11. The maximum temperature can be calculated from power Po of the associated equipment and the temperature class can then be determined. The characteristics of the energy storage must be specified precisely and must be taken into account when determining the overall safety of the system. Potentially explosive area Safe area Simple electrical equipment Example of an intrinsically safe circuit with simple electrical equipment Associated equipment, e.g. Ex i temperature measuring transducer Overview of simple electrical equipment Passive components Energy storage Energy sources* Pt 100 Capacitors Thermocouples Switches Coils Photocells Distributor boxes Resistors *Requirement U ≤ 1.5 V I ≤ 100 mA P ≤ 25 mW Phoenix Contact 27

5 Selecting devices The following section focuses on secondary explosion protection. When selecting devices, according to the types of protection, the user must analyze the type of danger and the duration and frequency of the danger. The type of danger is determined by examining the ignition source based on the ignition temperature and ignition energy. In the case of the duration and frequency of the danger, the relationship between zone classification and the equipment category and equipment protection level is established. 5.1 General requirements Equipment classification by directive The ATEX Directive requires that equipment be classified into groups and categories. Equipment group I includes underground and surface operations in mining. Equipment group II includes all other areas, such as the chemical industry, oil and gas processing, potentially explosive dusts in mills and silos, etc. The order they are arranged in is historical. Equipment categories 1 to 3 are a yardstick for how fail-safe the equipment is and are used to determine which of the different hazard zones of the potentially gas-explosive area it can be used in. Equipment classification by standard Since 2009, the IEC/EN 60079 series of standards has included an additional classification in accordance with gas groups (II) and dust groups (III) for surface use. However, the designation of gas groups from IIA to IIC and dust groups from IIIA to IIIC should not be confused with the ATEX Directive equipment groups, because the ATEX directives are differentiated solely by underground mining (I) and surface installations (II). Areas Equipment group in accordance with Directive 2014/34/EU IEC/EN 60079-0:2018 Mines susceptible to firedamp Group I Areas with a danger of gas explosions Areas with a danger of dust explosions Group II Group II Group I Group II Group III* IIA IIB IIC IIIA IIIB IIIC 28 Phoenix Contact

5.2 Type of hazard – source of ignition source consideration When considering the ignition source, potential sources of ignition are considered according to the ignition energy and surface temperature: Sparks/energy Ignition of the explosive atmosphere is prevented if the ignition energy of the equipment is lower than the minimum ignition energy of the surrounding substances (see 5.2.1 Groups). Hot surfaces The explosive atmosphere can be prevented from igniting if the surface temperature of the equipment is lower than the ignition temperature of the surrounding gas (see 5.2.2 Temperature classes). The following table provides an overview of the groups, the required ignition energy, and the resulting hazardousness of the substances as well as typical material examples. 5.2.1 Groups for gases and dusts in accordance with the standard Devices for use in Group II (gases) and III (dust) potentially explosive atmospheres are divided into groups (IIA, IIB, IIC, and IIIA, IIIB, IIIC), which indicate the maximum ignition energy of the device. A device may only be used if the maximum ignition energy of the device is lower than the minimum ignition energy of the substance (gas or dust mixture). A device with IIC marking may be used for all gases and a device with IIIC marking may be used for all dusts. Gases are more explosive than dusts: for example, devices with IIB are suitable for IIIC. The division into group II in accordance with A, B, C is particularly important for the types of protection, flameproof enclosure (Ex d) and intrinsic safety (Ex i). For flameproof enclosure, it is based on the experimentally determined limit gap width (MWG), which reduces the transmission of the energy of an explosion inside to the explosive atmosphere surrounding the housing so that it is below the minimum ignition energy of the material. For intrinsic safety, the minimum ignition current ratio is decisive, which results in the maximum ignition energy of the Ex i circuit and which must be below the minimum ignition energy of the respective gases. Group Required ignition energy Danger from substances Examples of substances IIA IIB IIC IIIA IIIB IIIC +++ ++ + +++ ++ + + ++ +++ + ++ +++ Acetone, ethane, ammonia, carbon monoxide. Propane, butane, gasoline, diesel fuel, acetaldehyde Methane, ethylene, ethyl ether, ethyl alcohol, hydrogen sulfide Hydrogen, acetylene, carbon disulfide Combustible flyings, e.g., cotton fibers Non-conductive dust, e.g., flour, wood Conductive dust, e.g., aluminum dust Phoenix Contact 29

5.2.2 Temperature classes/limits for gases and dusts by standard Temperatures for group I (pit mines/mine susceptible to weather) The maximum permissible surface temperature of the equipment depends on the type of coal dust deposit. Group I Temperature Conditions Mines susceptible to firedamp 150°C 450°C With deposits of coal dust on the equipment Without deposits of coal dust on the equipment Temperature classes for group II (gases) The explosive atmosphere can be prevented from igniting if the surface temperature of the equipment is lower than the ignition temperature of the surrounding gas. The surface temperature is valid for all parts of an item of electrical equipment that can come into contact with the explosive material. The majority of gases can be assigned to temperature classes T1 to T3. Temperature classes group II in accordance with IEC/EN 60079 and NEC 500 Temperature classes in accordance with IEC/EN 60079 Temperature classes in accordance with UL 913/ ISA 12.12.01 or NEC 500 Max. surface temperature of the equipment in °C Ignition temperature range of the gas in °C Examples T1 T2 T2A T2B T2C T2D T3 T3A T3B T3C T4 T4C T5 T6 T1 T2 T3 T4 T5 T6 30 Phoenix Contact >300 … ≤450 >450 >200 … ≤300 > 300 … ≤450 Carbon monoxide, methane, hydrogen >260 … ≤280 >230 … ≤260 >215 … ≤230 >200 … ≤215 >135 … ≤200 >200 … ≤300 >165 … ≤180 >160 … ≤165 >135 … ≤160 Acetylene, butane, ethylene Gasoline, hydrogen sulfide, cyclohexane >100 … ≤135 >135 … ≤200 >100 … ≤120 Acetaldehyde, diethyl ether (no other substances) >85 … ≤100 >100 … ≤135 No substances ≤85 >85 … ≤100 Carbon disulfide

Example The plan is to equip a housing with degree of protection IP54 (Ex eb IIC Gb) with approved terminal blocks and then comply with temperature class T6 in a potentially gas-explosive area. Since the gas can penetrate the housing, the maximum permissible temperature for T6 must not be exceeded either on the outside of the housing or inside at the terminals. Terminal housing for a zone 1 area with a danger of gas explosions Temperature limits for dust For areas with a danger of dust explosions, the maximum surface temperature is not specified in temperature classes, but as a temperature limit with a specified temperature value (°C). The maximum surface temperature of the equipment must not exceed the ignition temperature of a layer of dust or a cloud of combustible dust. This is because: TAmax = 2/3 TSparkling and TAmax = 2/3 TGlomerate – 75°C (up to 5 mm dust layer) The maximum surface temperature of the equipment is the lowest of the two temperatures TAmax. Further information can be found in the IEC/EN 60079-14 standard, for example. TAmax = The maximum surface temperature of the equipment TSparkling = Ignition temperature of the dust layer TGlomerate = Glow temperature of the dust layer Phoenix Contact 31

5.3 Duration and frequency of danger This section covers the relationship between zone classification as well as the equipment category and equipment protection level: Zone classification Both gas and dust-explosive areas are divided into three Ex zones. They differ in the duration and frequency of the hazard. The zone classification has already been described in detail in Section three. Equipment category and equipment protection level The equipment category or the equipment protection level indicates the safety of the device with regard to explosion protection. 5.3.1 Relationship between zones and equipment categories/equipment protection level Equipment categories and equipment protection levels describe the safety level and the protection level of devices. Which devices are suitable for which zone is shown in ATEX Directive 2014/34/EU via the equipment category (categories 1, 2, 3). In standard IEC/EN 60079-0, the applicability of the devices for the respective zones is described via the equipment protection level (EPL: a, b, c). For both the equipment category marking and the equipment protection level, the G stands for “gas” and the D for “dust”. For example, in gas applications, a device marked 1G and Ga, that is, with a very high level of safety and protection, is suitable for the most hazardous zone 0 and therefore also for all other gas zones. Structurally, this device is designed to still be safe in the event of two independent faults. Safety level or protection level Equipment category ATEX Directive 2014/34/EU Equipment protection level (EPL) Standard IEC/EN 60079-0 Very high – the device is still safe in the event of two independent faults High – in the event of an independent error, the device is still safe Normal – not failsafe Very high – the device is still safe in the event of two independent faults High – in the event of an independent error, the device is still safe Normal – not failsafe 1G 2G 3G 1D 2D 3D Ga Gb Gc Da Db Dc Zone classification Directive 1999/92/EC Gas zones Zone 0 Zone 1 Zone 2 Dust zones Zone 20 Zone 21 Zone 22 32 Phoenix Contact

6 Marking of Ex products In accordance with ATEX Directive 2014/34/EU and standard IEC/EN 60079-0, equipment must be labeled for potentially explosive areas. Devices for explosion protection in the EU must be labeled in accordance with both ATEX and the standard. 6.1 Marking of intrinsically safe equipment (Ex i field device) In accordance with IEC/EN 60079-11, an intrinsically safe equipment is an electrical device in which all circuits are intrinsically safe. It is installed in the potentially explosive area. Marking in accordance with ATEX Directive Marking in accordance with IEC/EN 60079-0 Conformity assessment in accordance with 2014/34/EU (ATEX) Electrical equipment X II 1 G Ex ia IIC T6 Ga Atmosphere (G = gas, D = dust) Equipment category (1, 2, 3) Equipment group (I, II) 34 Phoenix Contact Electrical equipment Equipment protection level (EPL) (Ga, Gb, Gc, Da, Db, Dc) Temperature class (for equipment used directly in the Ex area) (T1 … T6) Gas group (IIA, IIB, IIC) or dust group (IIIA, IIIB, IIIC) Type of protection (ia, ib, ic, eb, db, etc.) Explosion-proof

6.2 Associated marking of equipment (Ex i signal conditioners) Associated equipment in accordance with IEC/EN 60079-11 is an electrical device that contains both intrinsically safe and non-intrinsically safe circuits. It is designed in such a way that the non-intrinsically safe circuits cannot influence the intrinsically safe ones. The Ex i isolators are therefore particularly important, because they are absolutely necessary in every Ex i MCR circuit. The associated equipment is installed outside the Ex area and therefore does not require any information on the surface temperature. Marking in accordance with ATEX Directive X II (1) GD Marking in accordance with IEC/EN 60079-0 [Ex ia Ga] IIC Brackets = associated equipment “1” and “Ex ia” in brackets means that the connected intrinsically safe equipment may be installed up to zone 0. 6.3 Other markings to be displayed In addition to the marking, as shown in Sections 6.1. and 6.2., the company must be marked in accordance with the ATEX directive who is the notified body for production monitoring, the year in which the electrical device is manufactured, and conformity with other directive such as CE. c X II (1) G [Ex ia Ga] IIC 0344 BVS 08 ATEX E 054 X 19 Special conditions for safe use Certificate number Type-tested in accordance with 2014/34/EU (ATEX) Year of EU type test certificate Notified body Year of manufacture of the device Notified body for production monitoring Phoenix Contact 35

6.4 Relationship between equipment categories, EPL, and zones The equipment protection level (EPL) has been introduced in standard IEC/EN 60079-0:2007 and specifies the equipment protection level of the device or component. The equipment protection level should be viewed in the same way as the equipment categories used in the ATEX Directive. The new standard now provides a way of assigning devices to zones that is simpler than marking them according to their type of protection. Equipment category in accordance with ATEX Directive 2014/34/EU Equipment protection level (EPL) Zone Type of danger Gas Dust Mining 1G 2G 3G 1D 2D 3D M1 M2 Ga Gb Gc Da Db Dc Ma Mb 0 1 2 20 21 22 Continuous, long periods, frequent Occasional Not usually present, short periods only Continuous, long periods, frequent Occasional Not usually present, short periods only Continuous, long periods, frequent Occasional 6.5 Identification in the European Union – ATEX directives In Europe, the marking of equipment, components, and protective systems is based on the marking specified in directives and standards. Examples of marking in accordance with ATEX Directive 2014/34/EU and EN 60079-0 for gas atmospheres Gas atmosphere Electrical equipment Associated equipment Component EU type test certificate number Marking … U: component X: special operating conditions … in accordance with ATEX … in accordance with standard EN 60079-0:2006 … in accordance with standard EN 60079-0:2009 IBExU 09 ATEX 1030 c  II 3 G Ex-nA II T4 Ex-nA IIC T4 Gc BVS 08 ATEX E 094 X c 0344  II (1) G [Ex ia] IIC KEMA 07 ATEX 0193 U 0344  II 2 G Ex e II [Ex ia Ga] IIC Ex e IIC Gb Examples of marking in accordance with ATEX Directive 2014/34/EU and EN 60079-0 for dust atmospheres EU type test certificate number X: special operating conditions Marking … … in accordance with ATEX … in accordance with standard EN 61241:2006 … in accordance with standard EN 60079-0:2009 PTB 00 ATEX 0000 X TÜV 00 ATEX 0000 c  II 2 D Ex tD A21 IP65 T80°C Ex tb IIIC T80°C Db c  II [1] D [Ex iaD] [Ex ia Da] IIIC Dust atmosphere Electrical equipment Associated equipment 36 Phoenix Contact

6.6 Worldwide marking – IECEx With the IECEx system, marking is purely derived from the requirements of the IEC standards. Examples of labeling with IECEx certificate number and in accordance with IEC 60079-0 Gas atmosphere Electrical equipment Associated equipment Component Number of the IECEx Certificate of Conformity Marking … U: component X: special installation conditions … in accordance with standard IEC 60079-0:2004 IECEx IBE 09.0002X IECEx BVS 08.035X IECEx KEM 07.0057U Ex-nA II T4 [Ex ia] IIC Ex e II … in accordance with standard IEC 60079-0:2007 Ex-nA IIC T4 Gc [Ex ia Ga] IIC Ex e IIC Gb Examples of labeling with IECEx certificate number and in accordance with IEC 60079-0 Dust atmosphere Electrical equipment Associated equipment Number of the IECEx Certificate of Conformity Marking … U: component X: special installation conditions IECEx IBE 00.0000X IECEx BVS 00.0000X … in accordance with old standard IEC 61241-0:2005 … in accordance with standard IEC 60079-0:2007 Ex tD A21 IP65 T80°C Ex t IIIC T80°C Db [Ex iaD] [Ex ia Da] IIIC 6.7 Identification in North America – NEC and CEC In North America, approval can be obtained for associated intrinsically safe equipment (Associated Apparatus) either in accordance with the division concept (NEC 500/ UL 12.12.01 in conjunction with UL 913) or the zone concept (NEC 505 and NEC 506/UL 60079-0 ff.). Since the marking of the UL 60079 series corresponds to the IEC 60079 series due to extensive harmonization, only the example of a marking in accordance with the division concept is shown here. Examples of labeling with IECEx certificate number and in accordance with IEC 60079-0 Classification of the equipment Approval body in the USA: here UL 1M68 c for Canada; us for the USA  Listed CD-No: 12345678 Control drawing No. (control document) UL 12.12.01 Suitable for Class I, Div. 2, Groups A, B, C and D installation; UL 913 providing intrinsically safe circuits for use in Can be used in Div 2* for Class I: gases A: acetylene B: hydrogen C: ethylene D: propane Class I, Div. 1, Groups A, B, C, and D; Class II, Div. 1, Groups E, F, and G; and Class III, Hazardous Locations Gases Dusts Fibers Suitable for circuits in Div 1* * In accordance with NEC 500 Phoenix Contact 37

7 Installation of systems in potentially explosive areas If systems are installed in potentially explosive areas, a large number of precautionary measures must be taken. The operator is responsible for safe system operation and for the safety of personnel. In addition, they must ensure that the minimum requirements of the Operator Directive are applied. 7.1 Standards and directives Directive 1999/92/EC on the “minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres” relates to the operation of potentially explosive systems and is therefore aimed at operators. In accordance with Directive 1999/92/EC, the latter must assess, among other things, the explosion hazard of the plant (risk analysis), ensure the minimum regulations, divide the system into hazardous zones, and create an explosion protection document. The requirements to be observed are described and deepened in the IEC/EN 60079-10 and IEC/EN 60079-14 standards. In IEC/EN 60079-10, you find further details on zone classification and in IEC/EN 60079-14 you find details on the configuration, selection, and installation of electrical systems: for example, requirements on cable and line 7.2 Risk analysis The operator of a system must carry out a detailed assessment. This is based on standards IEC/EN 60079-10, IEC/EN 60079-14, and EN 11271, for example. The zones are determined and the permitted items of equipment selected based on this assessment. Every system must be examined with respect to its specific characteristics. The possible risks associated with an explosion occurring despite these measures must be examined in advance: for example, can chain reactions occur, what is the extent of damage to the buildings, and what effect does the explosion have on other parts of the system? It is possible for reciprocal effects that could never occur in the individual system to occur with neighboring systems. The risk assessment is usually carried out by a team which looks at all the relevant aspects of the system. In case of doubt, we recommend consulting additional experts. Risk assessment is the basis for all other measures to the point of system operation. These assessments 38 Phoenix Contact systems, details on type of protection- related installation specifications, and lightning protection measures. must be recorded in the explosion protection document. The guide referred to in Article 11 of Directive 1999/92/EC contains the following methodical procedure (flowchart derived):

Assessment flowchart for identifying and preventing explosion hazards: 1 Are combustible materials present? Yes 2 Can an explosive atmosphere arise if these materials are sufficiently distributed in the air? Yes 3 Where can explosive atmospheres occur? 4 Could a „hazardous explosive atmosphere“ be formed? Yes Further measures required! 5 Hazardous explosive atmospheres prevented from forming. (Primary explosion protection) No No No explosion protection measures required. No explosion protection measures required. No No explosion protection measures required. 6 Are measures in place to reliably prevent from the formation of hazardous explosive atmospheres? No Further measures required! 7 In which zones can the areas with hazardous explosive atmospheres be classified? Yes No further explosion protection measures required. 8 Effective sources of ignition avoided in areas with hazardous explosive atmospheres. (Secondary explosion protection) 9 Are measures in place to reliably avoid the ignition of hazardous explosive atmospheres? No Further measures required! Yes No further explosion protection measures required. 10 Effects of an explosion limited by constructional and organizational measures. (Tertiary explosion protection) 7.3 Explosion protection document The documentation is crucial for the safe operation of the system within the potentially explosive area. It is created prior to installation and must always be kept up to date. If changes are made to the system, all the influencing variables described must be taken into consideration. Example for the structure of the documentation Person responsible for the object Identified by name Description of the structural and geographical characteristics Plan of site and building, ventilation and air supply Description of procedures Description of the system from the point of view of explosion protection Materials data Risk assessment Protection concepts Organizational measures List of data with characteristics relevant to an explosion See guide above Zone classification, protection types applied Training, written instructions, clearance for work Phoenix Contact 39

8 Designing and installing intrinsically safe circuits To ensure that the intrinsically safe circuit is actually safe, the user or operator must carry out and implement the measures described in this section: from evaluating the suitability of the equipment with regard to the required level of protection and the available material groups, to proof of intrinsic safety, right through to installation. 8.1 Designing intrinsically safe circuits The operator determines the zone, the group, and the temperature class for the field device, based on the risk analysis which has been carried out. When selecting suitable devices, first check whether the devices are approved for the intended application. This can be done, for example, by marking the equipment in accordance with the table “Checking the suitability of the device using the marking” table: Intrinsically safe equipment (field device) Evaluation of the Ex marking Associated equipment X II 1 G Ex ia IIB T6 Ga Device category and device protection level (EPL) of the intrinsically safe equipment (field device) correspond to the specified zone. X II 1 G Ex ia IIB T6 Ga Type of protection is permitted in the specified zone. X II 1 G Ex ia IIB T6 Ga The device is approved for use in the prevailing gas atmosphere. As such, the corresponding equipment is marked with brackets and without specification of the temperature class/limits. X II (1) G [Ex ia Ga] IIC X II 1 G Ex ia IIB T6 Ga The device category and device protection level (EPL) of the associated equipment at least correspond the device category and the device protection level (EPL) of the field device. X II (1) G [Ex ia Ga] IIC X II 1 G Ex ia IIB T6 Ga Type of protection of the associated equipment matches that of the intrinsically safe equipment (field device). X II (1) G [Ex ia Ga] IIC X II 1 G Ex ia IIB T6 Ga The associated equipment is approved for the same group or one of a higher order. X II (1) G [Ex ia Ga] IIC 40 Phoenix Contact

8.2 Proof of intrinsic safety The intrinsically safe circuit generally consists of the intrinsically safe equipment, the associated equipment, and the connecting cables. To ensure that the device combination selected by the operator is actually intrinsically safe, proof of intrinsic safety must be performed for the corresponding circuit. The installer or operator is responsible for providing proof of intrinsic safety, not the manufacturer. This must be implemented in accordance with standard IEC/EN 60079-14 and, if necessary, other national standards and installation regulations. 8.2.1 Intrinsically safe circuits with one current source Generally speaking, intrinsically safe circuits have only one energy source or associated item of equipment. In the first step, the criteria are checked in accordance with the table “Checking the suitability of the device using the marking” table in Section 8.1. To aid planning and installation, it is advisable to keep the operating instructions for the equipment being used close at hand. The necessary parameters, that is, the safety data for verifying intrinsic safety, are taken from these. The next step is to check the safety-related data of the intrinsically safe circuit (voltage, current, power, capacitance, and inductance) in accordance with the figure below. Potentially explosive area (field) Safe area (control room) Associated equipment (power source) Intrinsically safe equipment 4 … 20 mA X X Conditions: Ui Ii Pi Li + Lc Ci + Cc ≥ ≥ ≥ ≤ ≤ Uo Io Po Lo Co 4 … 20 mA +24 V DC To demonstrate intrinsic safety, the five conditions specified in the figure “Criteria for fulfilling intrinsic safety” must be met. Phoenix Contact 41

Safety-related parameters and their abbreviations Common designations Europe USA/Canada For intrinsically safe equipment (field device): Max. input voltage Max. input power Max. internal capacity (or concentrated capacity in the intrinsically safe circuit) Max. internal inductance (or concentrated inductance in the intrinsically safe circuit) For associated equipment: Max. output voltage Max. output power Max. external (connectable) capacitance Max. external (connectable) inductance For cable/line: Cable/line capacity Cable/line inductance Ui Ii Ci Li Uo Io Co Lo Cc Lc Vmax / Ui I max Ci Li Voc Isc Ca Lex Ccable Lcable In the intrinsically safe circuit, all capacitances and inductances must be taken into account and compared with capacitance Co and inductance Lo of the associated equipment. In practice, it is particularly important to observe the capacitance, since this can restrict the length of cables or lines substantially. As a guide, capacitance Cc can be taken to be approximately 140 … 200 nF/km and inductance Lc approximately 0.8…1 mH/km. If in any doubt, always assume the worst case. Verification of intrinsic safety for simple intrinsically safe circuits The verification of an intrinsically safe circuit with linear characteristic curves described above is permitted if a simple intrinsically safe circuit is available. There are no external concentrated capacitances (Ci) and no external concentrated inductances (Li) present. The certified values for Co and Lo can be fully utilized. 42 Phoenix Contact

Verification of intrinsic safety for mixed intrinsically safe circuits A mixed intrinsically safe circuit exists when external concentrated capacitances (Ci) and/or external concentrated inductances (Li) are present. The verification of intrinsic safety verification described above is also permitted if a mixed intrinsically safe circuit is present and the following condition is met: total value of Li <1% of Lo or total value of Ci <1% of Co. The certified values for Co and Lo may also be fully utilized in this case. However, if we have a mixed intrinsically safe circuit with the condition that Li ≥1% of Lo and Ci ≥1% of Co, then only 50% of the certified values for Co and Lo may be utilized (“50% rule”). The following therefore applies accordingly: Ci + Cc ≤ 0.5 Co Li + Lc ≤ 0.5 Lo For better understanding, the assessment of whether the 50% rule is to be applied is shown as a graph in the following figure: If the 50% rule is to be applied, certified value pairs for C can also be used for the associated equipment Co and Lo are made available. This is the case with the Ex i isolator series Intrinsically safe circuit with a linear current source Li = 0 Yes No Ci = 0 Yes No Li <1 % from Lo Yes No Ci <1 % from Co Yes No Full values of Co and Lo can be used Reduced values (50%) for Co and Lo Can be used Graphical representation for the application assessment of the 50% rule in accordance with IEC/EN 60079-11 MACX Analog or MINI Analog, for example. This means that larger cable lengths can be achieved compared to the 50% rule. These value pairs can be found in the operating instructions, in the data sheet, or in the EU type test certificate for the corresponding equipment. 8.2.2 Intrinsically safe circuits with more than one current source In some other cases, there is more than one current source or more than one corresponding equipment in an intrinsically safe circuit. In these cases, proof of the intrinsic safety must be demonstrated using theoretical calculations or tests with the spark tester (in accordance with IEC/EN 60079-11). Whether or not a current addition is present must be taken into account. For these cases, it is therefore recommended to have the evaluation performed by an expert. Examples for the interconnection of several intrinsically safe circuits with linear current-voltage characteristic curves are listed in Appendix A and Appendix B of IEC/EN 60079-14:2013. When items of associated equipment with non-linear characteristic curves are interconnected, the evaluation based on the no-load voltage and the short-circuit current does not yield a result. However, the calculations can be performed on the basis of PTB report PTB-ThEx-10, “Interconnection of non-linear and linear intrinsically safe circuits”. This has been incorporated into IEC/EN 60079-25 (intrinsically safe systems). Here, graphical methods are used to evaluate intrinsic safety up to zone 1. Phoenix Contact 43

8.3 Examples for proof of intrinsic safety Potentially explosive area Safe area MINI Analog Pro or MACX Analog Intrinsically safe equipment (field device) II 1 G Ex ia IIB T6 Ga Associated equipment, e.g., Ex i signal conditioner II (1) G [Ex ia Ga] IIC Ui Ii Pi Ci Li + Cc + Lc ≥ ≥ ≥ ≤ ≤ Uo Io Po Co Lo Conditions for fulfilling proof of intrinsic safety Potentially explosive area Safe area MINI Analog Pro or MACX Analog Intrinsically safe equipment (field device) Associated equipment, e.g., Ex i repeater power supply PLC PLC The following shows examples for the design of intrinsically safe circuits based on typical applications such as analog IN and OUT, digital IN and OUT, and temperature measurements. If the five conditions from the following figure are met, proof is provided that the considered combination of the intrinsically safe equipment, the associated equipment, and the connecting cables is intrinsically safe. For proof of intrinsic safety, the cable capacities and inductances can be found in the data sheets of the cables. Alternatively, the following worst- case specifications can be assumed in accordance with IEC/EN 60079-14 for cable capacitances and cable capacities: Cable capacitance: 200 nF/km Cable inductances: 1 mH/km The parameters specified by the cable manufacturers are usually lower. 8.3.1 Analog IN Case 1: Ex i repeater power supply The device transmits analog 4 ... 20 mA signals from a passive measuring transducer from the Ex area to a controller and supplies the measuring transducer with power. 44 Phoenix Contact

Comparison of the safety data Intrinsically safe equipment: Pressure transmitter Ui Ii Pi Ci Li 30 V 100 mA 750 mW 0 nF 0 mH Cables/lines1) Length = 500 m Associated equipment: Ex i repeater power supply MACX MCR-EX-RPSSI-I Conditions met? ≥ ≥ ≥ ≤ ≤ Uo Io Po Co Lo 25.2 V 93 mA 587 mW IIC: 107 nF IIC: 3 mH +Cc +Lc +90 nF +0.5 mH Yes2) Yes2) Yes2) Yes2) Yes2) 1) Assumption: Cc = 180 nF/km, Lc = 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met. Case 2: Input signal conditioner, Ex i The device transmits analog 0/4 ... 20 mA signals from an active measuring transducer (4-wire measuring transducer) from the Ex area to a controller in an electrically isolated manner. The active measuring transducer is not supplied with energy by the Ex i input signal conditioner. In this case, the field device and not the associated equipment is the source. This changes the approach for verifying intrinsic safety in accordance with the following table: Potentially explosive area Safe area MINI Analog Pro or MACX Analog PLC Intrinsically safe equipment Associated equipment, e.g., Ex i (field device) input signal conditioner Comparison of the safety data Associated equipment: Ex i input signal conditioner MACX MCR-EX-RPSSI-I Cables/lines1) Length = 500 m Equipment: Flow transducer Conditions met? Ui Ii Pi 2) Ci Li 30 V 150 mA - 0 nF 0 mH ≥ ≥ - ≤ ≤ Uo Io Po Co Lo 28.3 V 130 mA 920 mW IIC: 100 nF IIC: 2 mH Yes3) Yes3) Yes3) Yes3) Yes3) +Cc +Lc +90 nF +0.5 mH 1) Assumption: Cc = 180 nF/km, Lc = 1 mH/km 2) In the approvals Pi is not listed. This means that in this circuit, Pi is not relevant and therefore does not need to be considered here. 3) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met. Phoenix Contact 45

8.3.2 Analog OUT Ex i output signal conditioners transmit analog 0/4 ... 20 mA signals from a controller to an actuator in the Ex area using an electrically isolated method. Potentially explosive area Safe area MINI Analog Pro or MACX Analog PLC Intrinsically safe equipment (field device) Associated equipment, e.g., Ex i output signal conditioner Scenario 1: Ex i output signal conditioner in a mixed intrinsically safe circuit without 50% rule Comparison of the safety data Intrinsically safe equipment: Control valve Ui Ii Pi Ci Li 28 V 110 mA 770 mW 5 nF 0 mH Cables/lines1) Length = 250 m Associated equipment: Ex i output signal conditioner MINI MCR-EX-IDS-I-I-PT Conditions met? ≥ ≥ ≥ ≤ ≤ Uo Io Po Co Lo 26.4 V 98 mA 647 mW IIC: 89 nF IIC: 2 mH +Cc +Lc +45 nF +0.25 mH Yes2) Yes2) Yes2) Yes2) Yes2) 1) Assumption: Cc = 180 nF/km, Lc = 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met. A mixed intrinsically safe circuit is present (external concentrated capacitances (Ci) and/or external concentrated inductances (Li) present), which meets the following condition: total value of Li <1% of Lo or total value for Ci <1% of Co. Thus, the certified values for C mayo and Lo may be fully exploited. 46 Phoenix Contact

Case 2: Ex i output signal conditioner in a mixed intrinsically safe circuit with 50% rule Comparison of the safety data Intrinsically safe equipment: Control valve Ui Ii Pi Ci Li 28 V 110 mA 770 mW 5 nF 0.3 mH Cables/lines1) Length = 100 m Associated equipment: Ex i output signal conditioner MINI MCR-EX-IDS-I-I-PT Conditions met? ≥ ≥ ≥ ≤ ≤ Uo Io Po 26.4 V 98 mA 647 mW 0.5*Co IIC: 44.5 nF 0.5*Lo IIC: 1 mH +Cc +Lc +20 nF +0.1 mH Yes2) Yes2) Yes2) Yes2) Yes2) 1) Assumption: Cc = 180 nF/km, Lc = 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met. A mixed intrinsically safe circuit is present (external concentrated capacities (Ci) and/or external concentrated inductances (Li) are present), which meets the following condition: total value of Li≥ 1% of Lo and total value of Ci≥ 1% of Co. Thus, the certified values for C mayo and Lo are not fully exploited. They must be reduced by 50%. The following applies accordingly: Ci + Cc ≤ 0.5 Co Li + Lc ≤ 0.5 Lo In order to enable longer cable lengths, certified value pairs for Co and Lo can be provided for the associated equipment if the 50% rule must be applied. This is the case with the Ex i isolator series MACX Analog or MINI Analog, for example. 8.3.3 Digital IN Ex i NAMUR signal conditioners transmit binary signals from sensors in the field to the controller using an electrically isolated method. This signal is created in the field by a switch or a NAMUR sensor. On the output side of the signal conditioner, the signal is forwarded to the controller as a binary signal either by a relay or by a transistor. An additional resistance circuit enables wire-break detection to be performed even for simple switches. The resistance ensures that a minimum current is always flowing, even when the switch is open. In this way, a line break can be identified. In the case of simple electrical equipment, such as, simple switches, only the inductance and capacitance values of the cables or lines are used for the comparison of safety data. For additional requirements relating to simple electrical equipment, see page 27. Potentially explosive area Safe area MINI Analog Pro or MACX Analog PLC Intrinsically safe equipment (field device) Associated equipment, e.g., Ex i-NAMUR signal conditioner With wire-break detection Without wire-break detection Phoenix Contact 47

Comparison of the safety data Intrinsically safe equipment: NAMUR sensors Ui Ii Pi Ci Li 13.5 V 37 mA 125 mW 50 nF 0.2 mH Cables/lines1) Length = 500 m Associated equipment: Ex i signal conditioner MINI MCR-EX-NAM-RO-PT Conditions met? ≥ ≥ ≥ ≤ ≤ Uo Io Po CO Lo 10.1 V 10.9 mA 28 mW IIC: 2.87 μF IIC: 300 mH +Cc +Lc +90 nF +0.5 mH Yes2) Yes2) Yes2) Yes2) Yes2) 1) Assumption: Cc= 180 nF/km, Lc= 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met. A mixed intrinsically safe circuit is present (external concentrated capacitances (Ci) and/or external concentrated inductances (Li) present), which meets the following condition: total value of Li <1% of Lo or total value for Ci <1% of Co. Thus, the certified values for C mayo and Lo may be fully exploited. 8.3.4 Digital OUT Ex i solenoid drivers link a switch or voltage source installed in the safe area to a field device using an electrically isolated method. Intrinsically safe solenoid valves, alarm modules or other intrinsically safe devices can be connected, and simple electrical equipment such as LEDs can be operated. The dimensions of a solenoid driver with a solenoid valve are described in the following as an example. In addition to verifying intrinsic safety, this also includes checking the function data: Potentially explosive area Safe area MINI Analog Pro or MACX Analog PLC Intrinsically safe equipment (field device) Associated equipment, e.g., Ex i solenoid driver Example for the Ex i MACX MCR-EX-SL-SD-24-48-LP solenoid driver Comparison of the safety data Intrinsically safe equipment: Solenoid valves Cables/lines1) Length = 100 m Associated equipment: Ex i solenoid driver MACX MCR-EX-SL-SD-24-48-LP Conditions met? Ui Ii Pi Ci Li 28 V 115 mA 1.6 W 0 nF 0 mH 48 Phoenix Contact ≥ ≥ ≥ ≤ ≤ Uo Io Po CO Lo 27.7 V 101 mA 697 mW IIC: 80 nF IIC: 5.2 mH +Cc +Lc +18 nF +0.1 mH Yes2) Yes2) Yes2) Yes2) Yes2) 1) Assumption: Cc= 180 nF/km, Lc= 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of intrinsic safety are therefore met.

Checking function data In addition to proof of intrinsic safety, functional data must also be checked. Especially with solenoid drives, this can be challenging, as there is no standard, such as with the NE43 for analog 4 ... 20 mA signals. The following example illustrates how the test can be performed for the functional compatibility of the solenoid valve and the solenoid driver. RI IV RC ISV Valve isolator UV USV Solenoid valve RSV Schematic diagram of the connection of a solenoid valve with a solenoid driver Key for schematic diagram Ri UV Rc Rsv Iv Isv Usv = Internal resistance of the valve isolator = Guaranteed voltage of the valve isolator without load = Maximum permissible cable resistance when valve isolator and valve are interconnected = Effective coil resistance of the solenoid valve (the copper resistance of the winding depends on the ambient temperature) = Maximum current that the valve isolator can supply = Current needed by the solenoid coil in order for the valve to pick up or be stopped = Voltage that is present at the coil with ISV (the copper resistance of the winding depends on the ambient temperature) The following conditions must be met for the function to be guaranteed: 1. Iv ≥ Isv 2. Rc= Uv - Ri - Rsv >> 0 Ω Isv 1. Function data check: Values of the solenoid driver: Uv= 24 V, Ri = 276 Ω, Iv = 48 mA Solenoid valve values: Rsv (65°C) = 566 Ω, Isv = 23 mA Iv = 48 mA ≥ Isv = 23 mA This means that the maximum current which the solenoid driver can supply is sufficient for operating the solenoid coil. 2. Determining the max. permissible cable resistance: Rc= Uv Isv - Ri - Rsv = 24 V 0.023 A - 276 Ω - 566 Ω = 201.5 Ω With a power cross section of 0.5 mm2 the maximum possible cable length is 2.798 km. However, since safety data from the Ex approval (see proof of intrinsic safety) must also be taken into account, the maximum permissible cable length in the example is 444 m for group IIC. A cable length of 3.66 km could be implemented for Group IIB with Lo = 20 mH and Co = 660. Here, the function data then limits the maximum possible cable length to 2.798 km. The calculation shows that the cable resistance may be 201.5 Ω without affecting the interconnection function. Recommendation: For the valve to function, Rc ≥ should be 25 Ω in order to have sufficient reserves for longer cable lengths. Guide values for cables and lines: Conductor resistance (supply/return line) 0.5 mm2 : 72 Ω/km 0.75 mm2 : 48 Ω/km 1.5 mm2 : 24 Ω/km Cable capacitance Approx. 180 nF/km Cable inductance Approx. 0.8 mH/km Phoenix Contact 49

8.3.5 Temperature measurement Temperature measuring transducers convert measuring signals from temperature sensors into analog standard signals (e.g., 0/4 ... 20 mA). Temperature sensors are designed as resistance thermometers (e.g., Pt 100, etc.) and thermocouples (e.g., J, K). In accordance with EN 60079-11, these can be regarded as simple electrical equipment, as they are passive (for further information on the topic of “Simple electrical equipment”, see Section 4.3.5 on page 27). Simple electrical equipment must meet the requirements of EN 60079-11 and must not impair the intrinsic safety of the circuit in which it is used. However, they are not covered under the ATEX Directive 2014/34/EU. If certified, intrinsically safe sensors are used; this reduces the amount of testing work required. There are two possibilities for converting the temperature signal into a standard signal for the controller: 1. Temperature measurement using an Ex i temperature measuring transducer The measuring signal of the Pt 100 resistance thermometer is routed to the temperature measuring transducer via a signal line. In the measuring transducer, the temperature signal is converted into a standard signal and the intrinsically safe and non-intrinsically safe circuits are isolated simultaneously. The measuring transducer is an item of associated equipment with intrinsic safety Ex ia type of protection. It is installed in a control cabinet in the safe area. Potentially explosive area Safe area MINI Analog Pro or Intrinsically safe equipment (field device) MACX Analog Associated equipment, e.g. Ex i temperature measuring transducer PLC Comparison of the safety data Intrinsically safe equipment: Resistance thermometer Cables/lines1) Length = 100 m Associated equipment: Ex i temperature measuring transducer MACX MCR-EX-RTD-I Conditions met? Ui Ii Pi Ci Li 7 V 400 mA 330 mW 150 nF 0.027 mH ≥ ≥ ≥ ≤ ≤ Uo Io Po CO Lo 6 V 16.8 mA 25.2 mW IIC: 600 nF IIC: 100 mH +Cc +Lc +18 nF +0.1 mH 1) Assumption: Cc= 180 nF/km, Lc= 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of narrowing reliability are therefore met. A mixed intrinsically safe circuit is present (external concentrated capacitances (Ci) and/or external concentrated inductances (Li) present), which meets the following condition: total value of Li <1% of Lo or total value for Ci <1% of Co. Thus, the certified values for C mayo and Lo may be fully exploited. 50 Phoenix Contact Yes2) Yes2) Yes2) Yes2) Yes2)

2. Temperature measurement using Ex i temperature transmitter and Ex i repeater power supply The measuring signal of the Pt 100 resistance thermometer is converted into a standard signal in the vicinity of the measuring point, that is, in potentially explosive areas. Loop-powered Ex i temperature measuring transducers and Ex i temperature transmitters are used for this. The standard signal is then routed to an Ex i repeater power supply. It is installed in the safe area. In the Ex i repeater power supply, the intrinsically safe and non-intrinsically safe circuit is separated. The safety-related data of the electrical equipment, the intrinsically safe temperature transmitter, and the Potentially explosive area Safe area PLC Intrinsically safe tem- perature head-mounted measuring transducer MINI Analog Pro or MACX Analog Simple electrical equipment (field device) Associated equipment, e.g., Ex i repeater power supply repeater power supply as the associated equipment must be compared. In this case, proof of intrinsic safety must therefore be carried out twice. Comparison of safety-related data for the Ex i temperature transmitter with Ex i repeater power supply Intrinsically safe equipment: FA MCR-EX-HT-1TS-I-OLP Ex i temperature transmitter Cables/lines1) Length = 100 m Associated equipment: Ex i repeater power supply MINI MCR-EX-RPSS-I-I Conditions met? Ui Ii Pi Ci Li 30 V 100 mA 800 mW 0 nF 0 mH ≥ ≥ ≥ ≤ ≤ Uo Io Po CO Lo 26.4 V 98 mA 647 mW IIC: 92 nF IIC: 2 mH +Cc +Lc +18 nF +0.1 mH 1) Assumption: Cc= 180 nF/km, Lc= 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of narrowing reliability are therefore met. Yes2) Yes2) Yes2) Yes2) Yes2) Comparison of the safety data of the Ex i resistance thermometer with Ex i temperature transmitter Intrinsically safe equipment: Resistance thermometer Cables/lines1) Length = 100 m Intrinsically safe equipment: Ex i temperature transmitter FA MCR-EX-HT-TS-I-OLP Conditions met? Ui Ii Pi Ci Li 7 V 400 mA 330 mW 150 nF 0.027 mH ≥ ≥ ≥ ≤ ≤ Uo Io Po CO Lo 4.3 V 4.8 mA 5.2 mW IIC: 3 μF IIC: 50 mH +Cc +Lc +18 nF +0.1 mH 1) Assumption: Cc= 180 nF/km, Lc= 1 mH/km 2) Conclusion: The conditions for fulfilling the proof of narrowing reliability are therefore met. A mixed intrinsically safe circuit is present (external concentrated capacitances (Ci) and/or external concentrated inductances (Li) present), which meets the following condition: total value of Li <1% of Lo or total value for Ci <1% of Co. Thus, the certified values for C mayo and Lo may be fully exploited. Yes2) Yes2) Yes2) Yes2) Yes2) Phoenix Contact 51

8.4 Installation of intrinsically safe circuits • In the case of armored, metal- sheathed or shielded cables/lines, intrinsically safe and non-intrinsically safe circuits can be laid in one and the same cable duct • Unused wires must be isolated from ground at both ends and isolated from other wires by suitable terminations. Conductive shields may only be grounded at one point, which is usually located in the non-potentially explosive area. See also the section “Grounding in intrinsically safe circuits” (8.4.2). In the control cabinet, the intrinsically safe circuits must be clearly marked. The standard does not stipulate a uniform process; rather, it simply indicates that a light blue color should preferably be used for marking. The neutral conductors of power cables are usually also marked by the color blue. In order to prevent any mix-up, different marking should be used for intrinsically safe circuits. A clear arrangement and spatial separation is advantageous in the control cabinet. The entire intrinsically safe circuit must be protected against the ingress of energy from other sources and against electrical and magnetic fields. 8.4.1 Installation of cables and lines When cables or lines are installed, they must be protected against mechanical damage, corrosion, chemical, and thermal effects. This is a binding requirement in the intrinsic safety type of protection. The accumulation of an explosive atmosphere in shafts, channels, tubes, and gaps must be prevented. Combustible gases, vapors, liquids, and dusts must not be able to spread through them either. Wherever possible, cables or lines should not be interrupted when routed within a potentially explosive area. If this is not possible, the cables or lines must only be connected in a housing with a degree of protection that is approved for the zone. If this is not possible for installation reasons, the conditions set out in standard IEC/EN 60079-14 must be met. The following also applies for intrinsically safe circuits, including those outside of the potentially explosive area: • Protection against the ingress of external energy • Protection against external electrical or magnetic fields. Possible cause: high- voltage overhead line or single-phase high-voltage lines • Single-core cables of intrinsically safe and non-intrinsically safe circuits must not be routed in the same cable • Several intrinsically safe circuits can be routed in multi-strand cables or lines 52 Phoenix Contact

Selection criteria for cables/lines for intrinsic safety protection Criterion Condition Note Insulated cables/lines Test voltage ≥500 V AC ≥750 V DC Conductor ground, conductor shield, and shield ground Diameter of individual conductors ≥0.1 mm Also for fine-stranded conductors Fine-stranded cables Protect against splicing e.g., with ferrules Multi-strand cables/lines Permitted Take into account the fault monitoring conditions in IEC/EN 60079-14 Parameters (Cc and Lc) or (Cc and Lc/Rc) If in doubt: worst case Distance between non-Ex i and Ex i Intrinsically safe circuits in potentially explosive areas Light blue cable in Ex zone Non-intrinsically safe circuits in the safe area Phoenix Contact 53

Special cases for grounding conductive shields in intrinsically safe circuits Reason Conditions a b c Shield has a high resistance; additional braided shield against inductive interference Robust ground conductor (min. 4 mm2), insulated ground conductor and shield: 500 V dielectric test, both grounded at one point, ground conductor meets the requirements of intrinsic safety and is specified on the certificate. Equipotential bonding between both ends Equipotential bonding across the entire area in which the intrinsically safe circuit is installed is ensured to a great extent. Multiple grounding via small capacitors Total capacitance is not above 10 nF. 8.4.2 Grounding in intrinsically safe circuits Potential differences can arise when intrinsically safe circuits are grounded. These must be taken into account when considering the circuits. Intrinsically safe circuits may be isolated from ground. The danger of electrostatic charge must be considered. Connecting via a resistor R = 0.2 … 1 MΩ in order to discharge the electrostatic charge does not count as a form of ground connection. An intrinsically safe circuit may be connected to the equipotential bonding system if this is only done at one point within the intrinsically safe circuit. If an intrinsically safe circuit consists of several electrically isolated sub-circuits, each section can be connected to ground once. If grounding is necessary for a sensor/actuator located in zone 0 due to its function, this must be implemented immediately outside of zone 0. Systems with Zener barriers must be grounded at these points. Mechanical protection against damage must also be provided if necessary. These circuits may not be grounded at another point. All electrical equipment that does not pass the voltage test with at least 500 V to ground is considered grounded. As for the electrical isolation of supply and signal circuits, the faults and transient currents in the equipotential bonding lines must be taken into account. 54 Phoenix Contact

8.4.3 Clearances to connection terminal blocks should become loose from the terminal block of their own accord. The cables or conductors should be shortened accordingly during installation. Special requirements in zone 0 Standard IEC/EN 60079-26, “Construction, test and marking of group II category 1 G electrical apparatus”, has been added to the IEC/EN 60079 series. It describes further requirements for using equipment with types of protection other than intrinsic safety in zone 0. d1 d2 Intrinsically safe circuit Intrinsically safe circuit Non-intrinsically safe circuit d3 d1 ≥ 3 mm d2 ≥ 6 mm d3 ≥ 50 mm Gaps in accordance with IEC/EN 60079-11 safe measuring devices must be used to measure intrinsically safe circuits. Failure to take the data from these measuring devices into account could jeopardize the intrinsic safety. Between different intrinsically safe circuits The clearance between terminal blocks in different intrinsically safe circuits must be at least 6 mm. The clearance between the conductive parts of the connection terminal blocks and conductive parts that can be grounded must be at least 3 mm. Intrinsically safe circuits must be clearly marked. Between intrinsically safe and other circuits The distance at terminal blocks between the conductive parts of intrinsically safe circuits and the conductive parts of non- intrinsically safe circuits must be at least 50 mm. The spacing can also be created using a partition plate made of insulating material or a grounded metal plate. Cables or conductors of intrinsically safe circuits must not come into contact with a non-intrinsically safe circuit, even if they 8.4.4 Maintenance and servicing No special authorization (e.g., fire certificate) is required for the maintenance of intrinsically safe circuits. The cables of the intrinsically safe circuits can be short circuited or interrupted without endangering the type of protection. Intrinsically safe equipment can be replaced (or plug-in modules removed) without the system having to be switched off. Hazardous currents or voltages are not usually present in intrinsically safe circuits, so they are safe for people. Approved intrinsically Phoenix Contact 55

8.5 Lightning and surge protection in intrinsically safe signal circuits 8.5.1 The hazard The effects of overvoltages on signal circuits can jeopardize the availability of process engineering systems. These hazardous effects may be caused by switching operations in the power grid, electromagnetic interference from frequency converters, or even occur due to lightning strikes during stormy weather. In this case, it is important to consider that the lightning strike even represents a hazard if the distance to the system is a few kilometers. The electromagnetic field that is created during the charge equalization creates a situation where transient overvoltages are coupled into the signal lines by capacitive and inductive coupling, with the effect playing out at the ends of the cables. Moreover, local ground potential 8.5.2 Effective voltage limitation increases can arise, creating short-term differences in ground reference potential between the system parts. Components that are used in signal circuits requiring explosion protection must meet minimum insulation requirements. These items of equipment for the most part have a dielectric strength of 1.5 kV (signal wire to ground, common mode). The electric strength between the wires (differential mode), on the other hand, often only amounts to a few hundred volts or less. Cables must have a minimum dielectric strength of 500 V AC rms. In practice, however, the voltage spikes that can occur with lightning and overvoltage events are much higher. It is assumed that amplitudes of several kilovolts occur in just a Surge protection products effectively and permanently limit the voltage peaks in the signal network. In the normal operating state, the surge protection item has a very high impedance between the signal wires and the ground potential, as well as between the signal wires themselves, and therefore has no influence on the measuring circuits or data transmission. However, if the locally present voltage increases to impermissible values due to electromagnetic coupling or potential differences, the surge protection module becomes low-impedance within microseconds. Charging can be equalized via the modules. The voltage level at the electronic devices to be protected remains so limited during this process that the critical values are not exceeded. Once the charge equalization has taken place, the surge protection products return to the normal high-resistance operating state. The surge protection must also be used on the premise that sparks cannot be created at an undefined position within the signal circuits and insulation materials. Therefore, surge protection also serves the purpose of secondary explosion protection with the aim of avoiding ignition sources in special situations where large short-term potential differences can occur. The sparkover voltage of the protective devices is in some cases higher than the 500 V AC rms dielectric test voltage. In other cases, the sparkover voltage is somewhat lower, so as to protect both the terminal devices and the insulation on the cables and lines in such a case. What must be taken into consideration here is that the protective device or the surge protection plug must be removed from the installation in the event of insulation measurements. Signal circuits are often designed using 56 Phoenix Contact few microseconds and the minimum insulation strength of the components in the signal circuit is exceeded. The larger the area of signal cables laid outdoors (called lightning protection zone 0), the greater the danger that the malfunctions in system parts or even destruction of electronic components can be caused by the effects described above. an insulated two-wire approach with additional cable shielding. In addition to the two clamping surfaces for the signal wires, a third clamping surface on the protective device for the cable shielding can be used for direct grounding over the mounting rail. In addition, some SURGETRAB versions, for example, also offer the option of grounding the cable shielding indirectly via an additional gas-discharge arrestor. This option may make sense if unwanted currents are flowing over the cable shielding and it is grounded at both endpoints.

8.5.3 Various types of protection A basic decision criterion for selecting a surge protective device for EX-protected areas is the type of protection and the associated approval. The Ex i type of protection is often found in the surge protection products, which are approved in accordance with ATEX and IECEx. Depending on the overall evaluation, the signal circuits can be routed to Ex zone 0. The surge protective devices are usually installed at the end points in the non-Ex area and in the Ex zones (up to zone 1). For surge protection in intrinsically safe Ex circuits, IEC/EN 60079-14 specifies that 10 pulses of the form (8/20) µs must be able to be safely managed with a discharge surge current of 10 kA. Another type of protection that is available is the increased safety Ex e. The use of such products is possible in Ex zone 2, taking certain conditions into consideration. Some products that are installed directly on the field device also feature Ex d type of protection approval and, together with the field device, form an explosion-proof unit. This solution can be installed in Ex zone 1 or 2. Approvals in accordance with NEC/UL are also available for surge protection products and are certified and considered separately. Phoenix Contact 57

8.5.4 Proof of intrinsic safety If surge protective devices are incorporated into the intrinsically safe circuit, then this must be taken into consideration when demonstrating intrinsic safety in accordance with IEC/EN 60079-25 Paragraph 13/ Appendix A. The data required for the calculation can be found in the ATEX/IEC certificate and the data sheets. Instances where individual parameters are not listed with an explicit value can be ignored. The following example illustrates how demonstration of proof might be carried out. Example: Tank farm A level measurement device on a fuel tank is connected to the control board via a long cable path of 500 m. Due to the explosive atmosphere that is always present inside the tank, Ex Zone 0 prevails there. The measurement values are converted to a unit current signal directly at the tank (4 to 20 mA) and then transmitted to the control board. This function unit is located in Ex zone 1. The SPD in the field is built directly on the measuring transducer. The distance of 1 m from Ex zone 0 should not be exceeded. The cables between the measuring sensor and the SPD must be designed so that they are protected against direct lightning interference. One possibility here would be to install the cables in a metal conduit. A significantly simpler approach is to use overvoltage protection items that can be mounted directly on the measuring head. An SPD is likewise deployed at the opposite end, so that the overvoltage is also effectively limited at the second cable end. See IEC/EN 60079-14 Paragraph 16.3 and other related materials for important contexts on the topic of surge protection in intrinsically safe circuits. 58 Phoenix Contact

Parameter Non-Ex zone Ex zone 2 Ex zone 1 Ex i signal isolators Surge protection Cables Surge protection Transmitters MACX-MCR- EX-SL-RPSSI-I TTC-6P-1X2-EX- 24DC-UT-I Uo = 25.2 V DC Ui1 = 30 V DC Io = 93 mA Ii1 = 400 mA (TA<50°C @ T4) Po = 0.587 W Pi1 = -- S-PT-EX(I)-24DC Ui2 ≤ 30 V DC FA MCR-EX-HT- TS-I-OLP-PT Ui3 ≤ 30 V DC Ii2 ≤ 350 mA (TA<50°C) Ii3 ≤ 130 mA Pi2 = 3 W Lo = 2 mH Li1 = negligible LC= 0.8 mH/km * 00 m = 0.4 mH Li2 = 1 μH Co = 107 nF Ci1 = negligible CC= 140 nF / km * 500 m = 70 nF Ci2 = 2 nF Pi3 = 800 mW Li3 = negligible Ci3 = negligible Verification U0 = 25.2 V ≤ Ui1 = 30 V  I0 = 93 mA ≤ Ii1 = 400 mA  L0 and C0 can be fully utilized. U0 = 25.2 V ≤ Ui2 = 30 V  I0 = 93 mA ≤ Ii2 = 350 mA  P0 = 587 mW ≤ Pi2 = 3 W  U0 = 25.2 V ≤ Ui3 = 30 V  I0 = 93 mA ≤ Ii3 = 130 mA  P0 = 587 mW ≤ Pi3 = 800 mW  L0 = 2 mH ≥ Li1 + LC + Li2 + Li3 = 0.4 mH + 1 µH = 0.4001 mH C0 = 107 nF ≥ Ci1 + Ci2 + Ci3 = 2 nF + 50 nF = 52 nF Phoenix Contact 59

9 Connection technology in the Ex area Connection technology plays an important role in the installation of signal and power supply cables in potentially explosive areas. This section provides an overview of the requirements for terminal blocks for intrinsically safe and non-intrinsically safe circuits and their installation in distributor boxes as well as cable entries in Ex d housings. 9.1 Terminal blocks for use in Ex e increased safety protection “Ex ec” is evaluated or certified, may only be used in category 3 or EPL Gc devices for zone 2 (gases). In addition to feed-through terminal blocks, items such as suitable function terminals, that is, fuse terminal blocks or test disconnect terminal blocks can be used as Category 3 components in zone 2 in the “Ex ec” type of protection. Approval of a component is indicated with the suffix “U”. Terminal blocks with increased safety “Ex e” type of protection must be appropriately marked. Using the UT 4 feed-through terminal block as an example, the elements of the marking are shown on the side. Terminal blocks must meet the requirements for the connection of external conductors. The IEC/EN 60079-7 standard for increased safety forms the basis for the corresponding inspection. As well as the type tests specified in the product standard, the additional requirements for increased safety can be summarized as follows: • Sufficiently large air clearances and creepage distances • Insulation materials that are resistant to temperature and aging • Protection against accidental loosening • Conductors must not be damaged during connection • Continuous sufficient clamping pressure • Contact reliability if temperature fluctuates • No transmission of clamping pressure via the insulating material • Multi-conductor connection only at suitable terminal points • Elastic element for multi-stranded conductors of 4 mm² and up • Specified torque for screw connection terminal blocks The technical data for terminal blocks in the Ex area is specified by the type examination and documented on the certificate. The basic data for the use of terminal blocks and accessories is as follows: • Rated insulation voltage • Rated voltage • Connectable conductor cross sections • Operating temperature range • Contact resistance in accordance with Section 8.2 of IEC/EN 60079-7 As approved components for the increased safety type of protection, terminal blocks are used in wiring spaces for devices for use in potentially explosive areas. The approval of components serves as the basis for certifying a device or protection system. Feed-through terminal blocks and protective conductor terminal blocks with the “Ex eb” type of protection are used in Category 2 and EPL Gb devices for zones 1 and 2 for gases. The associated wiring spaces and housings must meet the requirements of the respective type of protection and be approved for it. Terminal blocks for the type of protection 60 Phoenix Contact

Rating plate Packing label Marking requirements in accordance with IEC/EN 60079-0 for ATEX and IECEx Manufacturer’s name or trademark Type designation Marking for the type of protection Potentially explosive area L R or Potentially explosive area UT 4 Ex eb IIC Gb EU type examination certificate number in accordance with ATEX KEMA 04ATEX2048 U Certificate number in accordance with IECEx IECEx KEM 07.0010 U Marking requirements in accordance with ATEX Directive 2014/34/EU, Appendix II Name and address of the manufacturer Type designation Manufacturing date Potentially explosive area L R 32825 Blomberg, Germany UT 4 2019-01-17 ID number of the notified body (DEKRA Certification B.V.) Type-tested in accordance with ATEX Directive 2014/34/EU Equipment group Equipment category Identification letter for gas explosion protection Identification letter for dust explosion protection 0344 X II 2 G D Important notes: Depending on their maximum operating temperature, terminal blocks can be used up to a temperature class of T6. Refer to the respective installation instructions for precise information on the operating temperature range, as well as regarding installation, use, and the use of accessories, if applicable. Terminal block in Ex e Terminal blocks in Ex e housing Phoenix Contact 61

9.2 Terminal blocks for Ex i intrinsic safety type of protection Blue terminal housing for intrinsically safe circuits when the Ex e circuits are switched off. Corresponding warning labels must be attached. In accordance with IEC/EN 60079-14, terminal blocks qualify as simple electrical equipment for use in intrinsically safe circuits. A type examination by a notified body and marking are not required. If terminal blocks are color coded as part of an intrinsically safe circuit, they must be light blue. This means that terminals that comply with the industry standard IEC/EN 60947-7-1 can be used directly in intrinsically safe circuits so long as the air clearance and creepage distances as well as the clearances provided by solid insulation are met in accordance with IEC/EN 60079-11. However, the minimum clearance between uninsulated connections and grounded metallic parts or other conductive parts need only be 3 mm. These types of terminal blocks have been tested and generally satisfy the requirements of the intrinsic safety type of protection in accordance with IEC/EN 60079-0 and IEC/EN 60079-11, including the requirements on air clearances and creepage distances and clearances provided by solid insulation for circuits up to 60 V. A manufacturer’s declaration is provided to demonstrate compliance. The clearance between the external To separate intrinsically safe and non- connections between two different intrinsically safe circuits must be at least 6 mm. intrinsically safe circuits, a gap of least 50 mm must be created between the connection points. 9.3 Ex e and Ex i circuits in a single housing In electrical equipment, such as junction boxes, both intrinsically safe (Ex i) and increased safety (Ex e) circuits can be combined. Safe mechanical isolation and, if necessary, visual separation are prescribed here. It must be ensured that individual conductors do not come into contact with conductive parts of the other circuits when the wiring is disconnected from the terminal block. The distance between the terminal blocks must be at least 50 mm. Standard wiring procedures should also be observed so that it is unlikely that circuits will come into contact with one another even if a conductor becomes loose of its own accord. In control cabinets with a high wiring density, this separation is achieved by using either insulating or grounded metallic partition plates. Here too, the distance between intrinsically safe and non-intrinsically safe circuits must be 50 mm. Measurements are taken in all directions around the partition plate. The distance may be less if the partition plates come within at least 1.5 mm of the housing wall. Metallic partition plates must be grounded and must be sufficiently strong and rigid. They must be at least 0.45 mm thick. Non-metallic insulating partition plates must be at least 0.9 mm thick. The Ex e circuits must be additionally protected in the housing by a cover (at least IP30) if the end cover may be opened during operation. Otherwise, it is only permissible to open the end cover 62 Phoenix Contact

Clearance through partition plate between intrinsically safe circuits and other circuits Clearances between intrinsically safe circuits and other circuits must also be observed even when there are several DIN rails Partition plate between DIN rail to ensure clearance requires additional blocking (sealing), for example, by molding individual segments of the conduit system. Furthermore, condensation can easily form in conduit systems, which in turn can cause ground faults and short circuits as a result of corrosion. 9.4 Housing entries Two installation techniques are used worldwide: In Europe, cable or line entries in the flameproof enclosure and increased safety types of protection are most commonly used. In the USA and Canada, the conduit system is traditionally used. Cable or line entry Cable or line entries are most frequently designed in increased safety Ex e protection or flameproof enclosure Ex d. Flameproof enclosure cable or line entries are dust ignition-proof and are used in conjunction with flameproof enclosure housings. Increased safety cable or line entries are used in conjunction with housings in increased safety protection. The requirements regarding the IP protection of the housing must be taken into account when selecting the cable or line entry. Conduit system In the USA, particular importance is placed on providing the cables or lines with a high degree of mechanical protection, which is why the conduit system has become very widespread here. Comparison of cable or line entry with conduit system Compared to cables or lines or cable/ line entries, conduit systems are more laborious to install. In addition, a conduit system could easily allow fuels, potentially explosive gas mixtures, or similar items to be transported unintentionally from one system part to the next. Preventing this Cables (single wires) Molding compound Mineral fiber wool (asbestos-free) Cable protection tube (Ex d) Cable system with indirect entry (Ex e) Cable system with direct entry (Ex d) Conduit system with ignition lock (seal) Phoenix Contact 63

10 Installation of electrical devices for signal transmission in the Ex area Electrical equipment operated in systems with Ex areas is subject to different usage requirements. For MCR technology, for example, the following applications may occur: (1) sensors and actuators are distributed in all Ex zones, (2) signal conditioners are located in zone 1, zone 2 or in the safe area, (3) the controller is generally in the safe area. The instrumentation can be done in accordance with intrinsic safety type and/or in a different type of protection. 10.1 Intrinsically safe signal transmission in potentially explosive areas Sensors/actuators to be installed in zone 0 are primarily designed in intrinsic safety Ex ia protection. The intrinsically safe sensors/actuators are connected to the associated equipment with intrinsic safety Ex type of protection. The safety data required in order to dimension the intrinsically safe circuit is specified in the EU-type test certificate for the Ex i isolator. If Ex i isolators are only approved in accordance with the intrinsic safety type of protection, they may only be installed outside of the potentially explosive area. If the Ex i isolators need to be installed inside the potentially explosive area, they must be installed in such a way that they are protected by a different type of protection, such as flameproof enclosure. If an Ex i isolator is mounted in flameproof enclosure housing, it can also be installed in zone 1. In addition to the intrinsic safety protection type, Ex i isolators can be designed and approved in accordance with another type of protection, for example, increased safety “ec” type of protection. If this is the case, they can be installed directly in zone 2, taking certain conditions into account. The special installation conditions for installation in zone 2 are specified in the operating instructions of the Ex i isolator and include, for example, that a suitable and approved housing (IEC/EN 60079-15 and IEC/EN 60079-0) with at least IP54 protection class is used. Ex i isolators that are approved in accordance with the Ex ia type of protection can also be used for sensors/actuators that are approved in accordance with the Ex ib or Ex ic type of protection. 64 Phoenix Contact

10.2 Non-intrinsically safe signal transmission in potentially explosive areas In addition to intrinsically safe signal transmission in potentially explosive areas, there are also sensors/actuators that are designed in other types of protection: for example, pressure- resistant enclosure Ex d or increased safety Ex e. For this purpose, the use of non-intrinsically safe isolators is permitted. If non-intrinsically safe devices are to be installed in zone 2, the same requirements as previously described for the Ex i isolators apply. You need approval in accordance with Ex ec, which is accompanied by special conditions. The special installation conditions for installation in zone 2 are specified in the operating instructions of the isolator and include, for example, that a suitable and approved housing (IEC/EN 60079-15 and IEC/EN 60079-0) with at least IP54 protection class is used. If this approval is not granted, the isolators must be installed in a flameproof housing in accordance with Ex dc. However, this is usually significantly more expensive than an IP54 housing. A sensor/actuator with type of protection “ec” can be connected to an intrinsically safe isolator or a non-intrinsically safe isolator in zone 2. If it is connected to an Ex i isolator, the intrinsic safety protection principle no longer has any effect. The Ex i isolator must be marked as a non-intrinsically safe isolator in order to ensure that it is no longer used in any intrinsically safe circuits. When selecting suitable devices for zone 2, it must be ensured that the electrical data of the sensors/actuators is not exceeded. If the sensors/actuators are mounted in flameproof enclosure housing or if they have their own flameproof enclosure housing, they can also be installed in zone 1. The “ec” type of protection is also suitable if sensors/ actuators are to be used in zone 2. Phoenix Contact 65

10.3 Installation requirements The figure shows a range of options for installing electrical devices in areas with a danger of gas explosions. Special requirements regarding the configuration, selection, and installation of electrical systems in potentially explosive areas can be found in IEC/EN 60079-14. Other important factors when it comes to operating systems in potentially explosive areas are inspection, maintenance, and repairs. Specifications regarding these matters can be found in IEC/EN 60079-17 Example for the installation of electrical devices for signal transmission and IEC/EN 60079-19. Safe area PLC Zone 0 Zone 1 Zone 2 Sensor/actuator Ex ia Sensor/actuator Ex ia Sensor/actuator Ex ib Sensor/actuator Ex ic MINI-Ex [Ex ia] Ex ec MACX-Ex [Ex ia] Ex ec Sensor/actuator Ex ia Housing, e.g., Ex db Sensor/actuator Ex db eb Sensor/actuator Ex n, Ex ec, Ex dc MINI-Ex [Ex ia] Ex ec MACX-Ex [Ex ia] Ex ec Housing IP54* Housing IP54* MINI Ex ec MACX Ex ec MINI-Ex [Ex ia] Ex ec MACX-Ex [Ex ia] Ex ec MINI Ex ec MACX Ex ec 66 Phoenix Contact Sensor/actuator Ex n, Ex ec, Ex dc

11 Glossary Potentially explosive area (abbreviation: Ex area) An area in which a potentially explosive atmosphere is present or can be expected in such an amount that special precautionary measures are needed in the construction, installation, and use of electrical equipment. Ex component A part of electrical equipment for potentially explosive areas or a module (except for Ex cable/line entries) identified by the symbol U. Such a part may not be used by itself in such areas and requires an additional certificate when installed in electrical equipment or systems for use in potentially explosive areas. U symbol U is the symbol that is used after the certificate number to identify an Ex component. X symbol X is the symbol that is used after the certificate to identify special conditions for safe application. Note: The symbols X and U are not used together. Electrical equipment The entire set of components, electric circuits or parts of electric circuits that are usually located within a single housing. Intrinsically safe electrical equipment An item of equipment in which all circuits are intrinsically safe. Associated equipment An item of electrical equipment that contains both intrinsically safe and non- intrinsically safe circuits and is designed in such a way that the non-intrinsically safe circuits cannot influence the intrinsically safe ones. Note: This is also indicated by square brackets and round brackets in the marking. Associated equipment must be installed outside the potentially explosive area, provided that it does not comply with another suitable type of protection. Simple electrical equipment An item of electrical equipment or a combination of components with a simple design, with precisely determined electrical parameters, which does not impair the intrinsic safety of the circuit in which it is to be used. Intrinsically safe circuit A circuit in which neither a spark nor a thermal effect can cause the ignition of a particular explosive atmosphere. Abbreviations: Note: The index i denotes “in”, while o stands for “out”. A possible voltage addition must also be taken into consideration. See also IEC/EN 60079-14, Appendix B. Ii = Maximum input current The maximum current (peak value of the alternating current or direct current) that can be supplied via the connection elements of the intrinsically safe circuits without destroying the intrinsic safety. This means that no current higher than the value of the associated Ii may be fed into this intrinsically safe circuit. A possible current addition must also be taken into consideration here. See IEC/EN 60079-14, Appendix B here too. Pi = Maximum input power The maximum input power in an intrinsically safe circuit that can be implemented within electrical equipment without destroying the intrinsic safety. This means that no intrinsically safe circuit with power higher than Pi may be connected here. Note on Ui, Ii, and Pi: The EU-type test certificate often only provides one or two specifications for Ui, Ii or Pi. In this case, there are no restrictions for the terms that are not mentioned, since a further, internal limitation has already been implemented in this item of equipment. Ui = Maximum input voltage The maximum voltage (peak value of the AC voltage or DC voltage) that can be applied to the connection elements of intrinsically safe circuits without affecting the intrinsic safety. This means that no voltage higher than the value of the associated Ui may be connected to this intrinsically safe circuit. 68 Phoenix Contact

This means that Um = 250 V can be specified for the supply voltage and at the output Um = 60 V, for example. In accordance with IEC/EN 60079-14, Clause 12.2.1 2, it must also be ensured that items of equipment that are connected to non-intrinsically safe connection terminal blocks of associated equipment are not supplied with a supply voltage that is higher than the Um value specified on the rating plate of the associated equipment. For the above example, this means: A further item of equipment with a supply voltage of up to 250 V can be connected to the supply voltage of the associated equipment. Only one item of equipment with a supply voltage of up to 60 V can be connected to the output of the associated equipment. In = Rated fuse current The rated current of a fuse in accordance with EN 60127 or in accordance with the manufacturer’s specification. This is the nominal current that is specified for a fuse. Ta or Tamb = Ambient temperature The ambient temperature Ta or Tamb must be listed on the rating plate and specified on the certificate if it is outside the range of -20°C and +40°C. Uo = Maximum output voltage The maximum output voltage (peak value of the AC voltage or DC voltage) in an intrinsically safe circuit that can occur under idling conditions at the connection elements of the electrical equipment with any applied voltage, up to the maximum voltage including Um and Ui. This means that Uo is the maximum no-load voltage that can be present at the terminal blocks at the maximum supply voltage in the event of a fault. Io = Maximum output current The maximum current (peak value of the alternating current or direct current) in an intrinsically safe circuit that can be taken from the connection terminal blocks of the electrical equipment. This means that Io corresponds to the maximum possible short-circuit current Ik at the connection terminal blocks. Po = Maximum output power The maximum electrical power in an intrinsically safe circuit that can be taken from the equipment. This means that when a sensor or actuator is connected to this intrinsically safe circuit, this power must be taken into consideration, for example, when heating up or with the load in relation to the associated temperature class. Ci = Maximum internal capacitance Effective equivalent capacitance for the internal capacitances of the equipment at the connection elements. Li = Maximum internal inductance Effective equivalent inductance for the internal inductances of the equipment at the connection elements. Co = Maximum external capacitance The maximum value of the capacitance in an intrinsically safe circuit that can be connected to the connection elements of the electrical equipment without destroying the intrinsic safety. This means that this is the maximum value that all of the capacitances working outside of the equipment may attain. The external capacitances comprise the cable/line capacitances and the internal capacitances of the connected items of equipment. In the case of linear ohmic current limitation, Co depends on Uo. See also IEC/EN 60079-11, Appendix A, Table A2 and Figure A2 and A3. Lo = Maximum external inductance The maximum value of the inductance in an intrinsically safe circuit that can be connected to the connection elements of the electrical equipment without destroying the intrinsic safety. This means that this is the value that all of the inductances working outside of the equipment may attain in total. The external inductances comprise the cable/line inductances and the internal inductances of the connected items of equipment. In the case of linear ohmic current limitation, Lo depends on Io. See also IEC/EN 60079-11, Appendix A, Figure A4, A5, A6. Cc = Cable or line capacity Self-capacitance of a cable or line. This depends on the cable or line. It is generally between 140 nF/km and 200 nF/km. Lc = Cable or line inductance Self-inductance of a cable or line. This depends on the cable or line and is generally between 0.8 mH/km and 1 mH/km. Um = Maximum RMS value of the AC voltage or maximum DC voltage The maximum voltage that can be connected to non-intrinsically safe connection elements of the associated equipment without affecting the intrinsic safety. The value of Um can differ at the various connections of a device, as well as for AC and DC voltage. Phoenix Contact 69

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