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Quality inspection of electrical connections

Mechanical strength – IEC 60947-7-1/-2

The mechanical strength of the terminal point is checked in a practical test. For this purpose, the terminal points of the terminal blocks must be repeatedly connected without loss of quality of the terminal connection. Solid conductors with the rated cross section are used to connect and disconnect the terminal block five times over with the torque specified in the manufacturer's information. The test is carried out on the middle terminal block of a block of five. Before and after the test, the terminal block must pass a voltage-drop test. The terminal point must withstand repeated reconnection without sustaining noticeable damage. The voltage drop before and after the test must not exceed 3.2 mV nor must it exceed 1.5 times the value measured before the test. Terminal blocks from Phoenix Contact are suitable for repeated connection without any recognizable loss of quality. The extent of possible connections and disconnections can reach up to 5000 cycles, depending on the connection technology.

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Bending test: flexion test – IEC 60947-7-1/-2

Test equipment in accordance with the standard  

Test equipment in accordance with the standard

Correctly wired terminal blocks must offer a high degree of mechanical safety. This includes the reliable clamping of the conductor. Therefore, tests are performed with solid and stranded wires with the minimum cross section, with the rated cross section, and with the maximum cross section. A vertically fixed terminal block is connected to a conductor. A test weight corresponding to the cross section is attached at the end of the conductor. The conductor is fed through a central 37.5 mm aperture in a rotating disc and turned about its own axis 135 times. This procedure must not damage the clamping area on the conductor. Afterwards, the contact must pass a conductor pull-out test. Terminal blocks from Phoenix Contact are designed to ensure that the conductor makes contact in the clamping area gently. The conductor and contact point remain unaffected and retain the same properties even after repeated clamping.

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Cross section

[mm2]

Cross section

AWG

Distance H

[mm]

Mass

[kg]

Tensile force

N

0.2242600.210
0.34222600.215
0.5202600.320
0.75182600.430
1.0-2600.435
1.5162600.440
2.5142800.750
4.0122800.960
6.0102801.480
1082802.090
1663002.9100
2543004.5135
-33205.9156
3523206.8190
-13438.6236
5003439.5236
700036810.4285
9500036814351
-000036814427
120250 kcmil40614427
150300 kcmil40615427
185350 kcmil43216.8503
-400 kcmil43216.8503
240500 kcmil46420578
300600 kcmil46422.7578

Cross section

[mm2]

Cross section

AWG

Distance H

[mm]

Mass

[kg]

Tensile force

N

0.2242600.210
0.34222600.215
0.5202600.320
0.75182600.430
1.0-2600.435
1.5162600.440
2.5142800.750
4.0122800.960
6.0102801.480
1082802.090
1663002.9100
2543004.5135
-33205.9156
3523206.8190
-13438.6236
5003439.5236
700036810.4285
9500036814351
-000036814427
120250 kcmil40614427
150300 kcmil40615427
185350 kcmil43216.8503
-400 kcmil43216.8503
240500 kcmil46420578
300600 kcmil46422.7578

Conductor pull-out test – IEC 60947-7-1/-2

Absorption of tensile force on a 10 mm² spring-cage terminal block  

Absorption of tensile force on a 10 mm² spring-cage terminal block

Tensile forces can affect the terminal point during wiring or operation. Correctly wired terminal blocks must therefore offer a high degree of mechanical safety. To test the tensile load capacity of a terminal point, the terminal point must withstand a given tensile force based on the cross section for over 60 seconds. This test is performed after the bending test. Performing these two tests directly one after the other intensifies the requirements. The tensile force exerts stress on the conductor at the terminal point. The conductor must be held within the terminal point without sustaining damage. The test results for terminal blocks from Phoenix Contact are up to 150% above the required minimum values.

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Conductor pull-out forces according to IEC 60999 / EN 60999 / VDE 0609-1, Table III (up to 35 mm²)

Conductor cross section

[mm2]

Conductor cross section

AWG/kcmil

Tensile force

[N]

0.2

-

24

22

10

20

0.5

0.75

20

18

15

30

1.0

1.5

-

16

35

40

2.5

4.0

14

12

50

60

6.0

10

10

8

80

90

16

25

6

4

100

135

-

35

3

2

156

190

-

50

1

0

236

236

70

95

00

000

285

351

-

120

0000

250

427

427

150

185

300

350

427

503

-

240

400

500

503

578

300600578

Conductor cross section

[mm2]

Conductor cross section

AWG/kcmil

Tensile force

[N]

0.2

-

24

22

10

20

0.5

0.75

20

18

15

30

1.0

1.5

-

16

35

40

2.5

4.0

14

12

50

60

6.0

10

10

8

80

90

16

25

6

4

100

135

-

35

3

2

156

190

-

50

1

0

236

236

70

95

00

000

285

351

-

120

0000

250

427

427

150

185

300

350

427

503

-

240

400

500

503

578

300600578
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Tight fit of the terminal block – IEC 60947-7-1/-2

Testing the tight fit of a terminal block  

Testing the tight fit of a terminal block

Besides the reliable contacting of the conductor, the terminal block itself must be able to withstand forces without coming loose from its support. Furthermore, no unacceptable damage may occur. To test whether the fit is tight, a terminal block is mounted on a standard DIN rail in accordance with the manufacturer's information. Then steel rods with a length of 150 mm are clamped into the terminal points. Tensile and pressure forces based on the cross section are exerted on the terminal points and the latching of the terminal block with a lever distance of 100 mm. The terminal block must not come loose or break off the rail. The structural design of the terminal blocks from Phoenix Contact ensures a reliable tight fit on different DIN rail systems.

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Cross section

[mm2]

Cross section

AWG

Force

[N]

Diameter of the steel bar

[mm]

0.751811.0
1 11.0
1.51611.0
2.51411.0
41211.0
61052.8
10852.8
352105.7
500105.7
240500 kcmil2020.5

Cross section

[mm2]

Cross section

AWG

Force

[N]

Diameter of the steel bar

[mm]

0.751811.0
1 11.0
1.51611.0
2.51411.0
41211.0
61052.8
10852.8
352105.7
500105.7
240500 kcmil2020.5

Dielectric test – IEC 60947-7-1/-2/UL 1059

This electrical test is used to demonstrate adequate creepage distances. To test that the distances between the potentials of two neighboring terminal blocks and between a terminal block and the DIN rail are sufficient, an appropriate test voltage is applied. Rated insulation voltage (Ui) is the r.m.s. or DC voltage value that is permanently acceptable as a maximum when correctly used. The test voltage must be applied for over 60 seconds. The assignment illustrated in the table is to be used as the basis for this.

Rated insulation voltage
Ui

[V]

Test voltage

(r.m.s)

[V]

Ui ≤ 601000
60 < Ui ≤ 3001500
300 < Ui ≤ 6901890
690 < Ui ≤ 8002000
800 < Ui ≤ 10002200
1000 < Ui ≤ 1500 

Rated insulation voltage
Ui

[V]

Test voltage

(r.m.s)

[V]

Ui ≤ 601000
60 < Ui ≤ 3001500
300 < Ui ≤ 6901890
690 < Ui ≤ 8002000
800 < Ui ≤ 10002200
1000 < Ui ≤ 1500 

IEC 60947-7-1/-2
No sparkover or disruptive discharge may occur during testing. Creepage currents must stay below 100 mA.
UL 1059
Test voltage = 1000 V + 2 x rated insulation voltage Ui. Terminal blocks from Phoenix Contact with
a rated insulation voltage of 800 V consistently pass the dielectric test with 2000 V ~.

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Surge voltage test – IEC 60947-7-1/-2

The oscilloscope shows the time curve for a surge voltage pulse  

Time curve for a surge voltage pulse

Proof of sufficiently large clearances between two neighboring potentials is provided by means of the surge voltage test. The test with the surge voltage is carried out five times at intervals of at least 1 s. The test is carried out for each polarity depending on the rated insulation voltage. The distance between neighboring terminal blocks or between the terminal block and rail is examined. There must be no unintentional sparkovers during the test. Rated surge voltages for Phoenix Contact terminal blocks are between 6 and 8 kV. Operationally reliable use of the documented operating voltages of the terminal blocks is thereby effectively confirmed.

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Voltage-drop test – IEC 60947-7-1/-2

Voltage-drop test at terminal points  

Voltage-drop test at terminal points

In every terminal point of a terminal block, one or more conductors are connected – depending on the connection technology. Current transfer is strongly affected by the electrical resistance between the conductor and the current bar. High-quality contacts create a gas-tight connection. This is the only way to ensure a permanently reliable connection. This electrical test therefore determines the voltage drop on a terminal block (two terminal points). Conclusions can therefore be made regarding the contact resistance and the contact quality. The terminal blocks are wired with the rated cross section. For measuring purposes, a direct test current corresponding to 0.1 times the current carrying capacity of the rated cross section is applied to the terminal blocks. The voltage drop is picked off at a distance ≤ 10 mm from the middle of the terminal point. At a room temperature of ~20°C, the voltage drop must not exceed 3.2 mV per terminal block before or after the test, nor must it exceed 1.5 times the value measured at the start of the test. Terminal blocks from Phoenix Contact are up to 60% below the limit values required by standards.

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Rated cross section

[mm2]

Current carrying capacity

[A]

Rated cross section

AWG

Current carrying capacity

[A]

0.24244
0.56208
0.7591810
113.5--
1.517.51616
2.5241422
4321229
6411038
1057850
1676667
351252121
501500162
952320000217
15030900000309
240415500 MCM415

Rated cross section

[mm2]

Current carrying capacity

[A]

Rated cross section

AWG

Current carrying capacity

[A]

0.24244
0.56208
0.7591810
113.5--
1.517.51616
2.5241422
4321229
6411038
1057850
1676667
351252121
501500162
952320000217
15030900000309
240415500 MCM415

Temperature-rise test – IEC 60947-7-1/-2/UL 1059

The rise in temperature of a terminal block must be kept to an absolute minimum. The contact resistance must therefore be as low as possible. This test is used to document the rise in temperature that occurs at room temperature during exposure to a test current.

IEC 60947-7-1/-2

Five terminal blocks are horizontally mounted on a rail and connected in series using conductor loops with the rated cross section, each measuring 1 or 2 m in length. The terminal blocks are exposed to a test current that is as high as the current carrying capacity of the rated cross section. The rise in temperature at the middle terminal block is documented. Assuming a room temperature of ~20°C, a maximum rise in temperature of 45 K is permitted in the terminal block. Additionally, a voltage-drop test must be performed on the terminal block as a final step.

UL 1059

The process basically corresponds to the IEC test, only the conductor lengths differ. Three terminal blocks are horizontally mounted adjacent to one another. The measurement is taken at an ambient temperature of 25°C, whereby a maximum rise in temperature of 30 K (measured as close as possible to the terminal point) is permitted. Due to the high-quality contact materials used in terminal blocks from Phoenix Contact, all connection technologies offer lower temperature-rise values than required by the specified standards.

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Current carrying capacity

Standard IEC 60947-7-1/ EN 60947-7-1/DIN VDE 0611-1 specifies the test currents for the individual conductor cross sections listed in the adjacent table. The corresponding currents are listed with the connection data for the individual terminal blocks. The type tests of terminal blocks are based on this data.

Test currents according to IEC 60947-7-1/EN 60947-7-1

Table 5           
Rated cross section[mm2]0.20.50.751.01.52.5461016
Test current[A]46913.517.52432415776
Rated cross section[mm2]2535507095120150185240300
Test current[A]101125150192232269309353415520
Table 5           
Rated cross section[mm2]0.20.50.751.01.52.5461016
Test current[A]46913.517.52432415776
Rated cross section[mm2]2535507095120150185240300
Test current[A]101125150192232269309353415520
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Base and derating curve, test setup, ambient temperature

Derating curve for plug-in terminal blocks  

Derating curve for plug-in terminal blocks

To determine the current carrying capacity of plug-in terminal blocks, arrangements with a variety of positions are selected, which are electrically connected in series using conductors with the same cross section. For the practical determination of the derating curves, the current carrying capacity of the plug-in terminal blocks is determined in accordance with DIN EN 60512-5-1. Here, after applying various currents (e.g., 10 A, 17.5 A, 24 A, and 32 A) and setting the temperature balance, the maximum temperature increase that occurs on the test objects is measured. When the upper limiting temperature of the insulation material – here, always assumed to be 100°C – is taken into account, these values yield a derating curve dependent on the ambient temperature: the “base curve”.

An adjusted capacity curve – the “derating curve” – is generated according to DIN EN 60512-5-2. In accordance with this standard, the permissible load current is 0.8 times the respective base current. The derating factor “...takes into account manufacturing tolerances in the contact system of connectors as well as uncertainties in the temperature measurement and the measuring arrangement”. For the majority of items in this catalog, derating curves are provided for 2, 5, 10, and 15-pos. arrangements.

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SCCR – short-circuit current rating

As of April 2006, the NEC (National Electrical Code) requires the short-circuit withstand capability of industrial controllers to be specified. These SCCR (short-circuit current rating) values can be calculated with the aid of UL 508A. In the USA, the calculation must be summarized on the rating plate of all industrial switchgear, for all main circuits as well as for the feed-in of the control voltage supply. Standard values for non-specified components are listed in UL 508A – Table SB 4.1. A value of 10 kA is assumed for terminal blocks. Phoenix Contact produces a wide range of products with considerably higher SCCR values than this. The terminal blocks in the CLIPLINE complete system are all documented as having SCCR values of 100 kA. The SCCR values for terminal blocks from Phoenix Contact are listed in detail in UL file number E60425. The UL file is stored in and can be retrieved from the UL database via the following link:

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Short-time withstand current – IEC 60947-7-1/-2

Maximum contact reliability, illustrated with a plug-in spring-cage terminal block  

Maximum contact reliability, even under extreme overload

Terminal blocks must, in practice, also be capable of resisting short-circuit currents until the relevant safety equipment cuts off the current without sustaining any damage. This can take up to several tenths of a second. For testing purposes, a terminal block is mounted on the support and wired to a conductor with the rated cross section. Protective conductor terminal blocks are subjected in three stages of one second each to a current density of 120 A/mm2 of the rated cross section. The requirements are met if, after the test, the individual parts are undamaged and their further use is guaranteed. Before and after the test, the terminal block must pass the voltage-drop test. The voltage drop before and after the test must not exceed 3.2 mV per terminal block nor must it exceed 1.5 times the value measured before the test. In the case of a 240 mm2 high-current terminal block from Phoenix Contact, a test current of 28800 A is passed through the terminal block for one second without loss of quality.

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Corrosion test – DIN 50018

Metal parts after the corrosion test  

Metal parts after the corrosion test

The pivotal role of the metal parts of electrical connections becomes particularly apparent in aggressive environments. Corrosion-free contact areas are a prerequisite for low-resistance and therefore high-performance connections. This test method describes a corrosion test in condensation climates with an atmosphere that contains sulfur dioxide. Acidic compounds < Ph 7 form during the test and attack the metal surfaces. Two liters of distilled water and one liter of SO2 gas are introduced into the test chamber. At a test temperature of 40°C, sulfurous acid forms during the test. After eight hours of testing, the test objects are left to dry for 16 hours with the door open. At the end of the test, the test objects are visually inspected and the contact resistance is measured in order to show the influence of this corrosion test on the contact point in more detail. Phoenix Contact terminal blocks create high-quality gas-tight connections. Even aggressive media cannot impact the connection.

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Aging test – IEC 60947-7-1/-2

Current and temperature in relation to time  

Current and temperature in relation to time

From the point of view of long lifecycles of the terminal blocks, the aging behavior also plays an important role. In this test, the contact quality is verified by means of simulated aging. To simulate several years of use, five terminal blocks are mounted horizontally on a rail and connected in series using conductors with the rated cross section. The voltage drop is measured at each terminal block. These terminal blocks are connected by conductors with a minimum length of 300 mm. The minimum temperature in the climate cabinet is set to 20°C and the maximum temperature to 85°C. During the heating phase and the 10-minute pause phase with maximum temperature, the rated current flows. As a result, the maximum permissible operating temperature of the test object (130°C maximum) is reached. This is followed by the cooling phase. The voltage drop is always measured after 24 cycles in the cooled down state (approximately 20°C). The test consists of a total of 192 cycles. The voltage drop must not exceed 3.2 mV initially. During or after testing, it must not exceed 4.8 mV or 1.5 times the value measured after the 24th cycle. Terminal blocks from Phoenix Contact are designed for extreme durability even under difficult temperature conditions. Plastic as well as metal parts provide sufficient safety reserves.

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Environmental testing methods – IEC 60068-2-42/43

The mechanical and electrical service life of terminal blocks is directly dependent on the metal parts and insulation materials used. To evaluate the climatic effects on electrical connections, terminal blocks are subjected to various environmental simulation tests. The conductor contact points, the knife disconnect points, and the test contacts are included in these tests. The contact resistance values, the secure fit of the conductor, and the visual assessment of the contact points after each test serve as evaluation criteria.

  • 10-day storage in aggressive SO2 industrial atmospheres at 25°C and 75% humidity.
  • 4-day storage in aggressive H2S atmospheres at 25°C and 75% humidity.

After the test has been completed, the contact resistance must not exceed 1.5 times the initial value. The function of the terminal block must be ensured without any limitation. The high standard of quality of Phoenix Contact terminal blocks is achieved by using corrosion-resistant, high-grade copper alloys.

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Salt spray – IEC 60068-2-11/-52

Push-in Technology salt spray test  

Push-in Technology salt spray test

Particularly in shipbuilding, technical components have to function continuously in corrosive atmospheres. The salt content of the air combined with the increased humidity places high demands on the metal parts used. The impact of the climate at sea can be simulated on the basis of the above standard.

The resistance of the materials is tested with salt spray in corrosive atmospheres. The test objects are placed in the test chamber and subjected to a finely dosed spray of 5% sodium chloride solution (NaCl: pH value 6.5 - 7.2) at a temperature of 35°C for a period of 96 hours.

At the end of the test, the test objects are visually inspected and an electrical test is performed to show the influence of this corrosion test on the contact point in more detail.

All Phoenix Contact terminal blocks, whatever their connection technology, create gas-tight connections. This means that the contact point is protected against corrosion even under extreme climatic conditions.

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Temperature shock test – DIN EN 60352 T4

Diagram for the voltage-drop test on more than 200 test objects following the test  

Voltage-drop test on more than 200 test objects following the test

In process engineering, rapid changes in temperature frequently occur near process-related sources of heat and cold. This test verifies that the contact quality of the terminal points remains consistently high even in the case of rapid changes in temperature. For testing purposes, five terminal blocks are mounted on the support and wired to a conductor with the rated cross section. The structure is subjected to rapid temperature changes using a two-chamber method. The temperatures lie close to the upper and lower limiting temperatures of the terminal block. This is generally a temperature range of -60°C to +100°C. The dwell time in each climatic chamber is 45 minutes, whereby the change takes place within a few seconds. This change is performed for 100 cycles. The requirements are met if, after the test, the individual parts are undamaged and their further use is guaranteed.

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Vibration test – DIN EN 61373

Vibration test  

Vibration test

Broadband noise (intensity according to DIN EN 50155)

In transportation technology, terminal blocks are exposed to constant vibrations and shocks. These vibrations occur particularly in the vicinity of engines, rotating drives, and axles. For a practical simulation of the vibration stress, the test objects are subjected to broadband noise-induced vibrations. This means that realistic accelerations are generated at the terminal block and the connected conductor. During the category 1 B test, the test objects are exposed to a frequency range of 5 Hz to 150 Hz. The r.m.s. value of the acceleration is up to 5.72 m/s2. The test objects are tested for 5 hours on each of the three axes (X, Y, Z). In addition to the vibrations, the electrical contact is monitored during the test to make it more difficult. No damage may occur to the terminal blocks that would impair their further use. In addition, no contact interruptions > 1 μs are permitted during the test. All Phoenix Contact terminal blocks, whatever their connection technology, meet this high vibration requirement.

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Vibration test - IEC 60068-2-6

Vibration test  

Vibration test

This test demonstrates the vibration resistance of a terminal connection subjected to permanent vibrations. Harmonic, sinusoidal vibrations are applied to the test object to simulate rotating, pulsating or oscillating forces. The test is performed on each of the three spatial axes (X, Y, Z). The test is performed over a frequency range of 5 Hz to 150 Hz. This equates to a speed of one octave per minute. The r.m.s. value of the acceleration is up to 40 m/s2. The test objects are tested for 2 hours on each of the three axes (x, y, z).

No damage may occur to the terminal blocks that would impair their further use. In addition, no contact interruptions of > 1 μs are permitted during the test. The contact resistance is measured before and after the test.

All connection technologies meet the requirements of the standard with no interruption of the electrical contact. They are therefore particularly suitable for challenging applications in which the reliable function of the terminal connection must be ensured, even when subjected to vibrations.

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Shock testing – IEC 60068-2-27

Shock diagram with 3 ms/350g  

Shock diagram with 3 ms/350g

This test is performed to test and document the resistance of a terminal connection to sporadic shocks of varying intensity. Intensities from DIN EN 50155 and DIN EN 61373 (European standard for railway applications) are used to simulate the load in rail transport. Acceleration and duration are specified in order to define the shock. IEC 60068-2-27 prescribes three positive and negative shocks on each of the three spatial axes (X, Y, Z). The simulated accelerations reach 50 m/s2 with a shock duration of 30 ms. No damage may occur at the terminal connection that would impair further use. The contact behavior on the test objects is monitored during the test. When the railway standard is applied, no contact interruptions > 1 μs are permitted. Phoenix Contact terminal blocks achieve this shock resistance and are suitable for applications with the most extreme vibrations.

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Air clearances and creepage distances – IEC 60947-7-1 / UL 1059

Carrying out a dimensional check of air clearances and creepage distances confirms that electrical insulation properties are adequate with respect to the following:

  • Application
  • Expected contamination
  • Ambient conditions

The minimum distances are defined in IEC 60947-1 and UL 1059. The distance is verified by measuring between two neighboring terminal blocks and the support, taking into account the shortest distances.

For the clearance this means: the clearance is the shortest distance in the air between two conductive parts. The deciding factors for rating the minimum clearance values are the rated surge voltage and the overvoltage category of the terminal block.

For the creepage distances this means: the creepage distance is the shortest distance along the insulating body between two conductive parts. The deciding factors for determining the minimum creepage distance are the rated voltage, the pollution degree, and the insulation material group of the terminal block. The minimum values can be taken from the table values for the relevant standards.

IEC 60947-7-1
Phoenix Contact terminal blocks are designed with overvoltage category III and pollution degree 3 with the required distances.

UL 1059
Phoenix Contact terminal blocks are generally designed for a nominal voltage of 600 V in Use Group C. Detailed information can be found in the data sheets or the catalog documentation.

UL
Use Group
Definition

Maximum voltage

[V]

AOperating elements, consoles, and similar devices

150

300

600

BConventional devices, including office and electronic data processing equipment and similar devices

150

300

600

CIndustrial applications, without restrictions

150

300

600

DIndustrial applications, equipment with limited rating

300

600

UL
Use Group
Definition

Maximum voltage

[V]

AOperating elements, consoles, and similar devices

150

300

600

BConventional devices, including office and electronic data processing equipment and similar devices

150

300

600

CIndustrial applications, without restrictions

150

300

600

DIndustrial applications, equipment with limited rating

300

600

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