The compact design saves on weight and creates space.
When it comes to designing fieldbus installations in process engineering, availability plays a crucial role. This applies to PROFIBUS PA as well as FOUNDATION Fieldbus.
Field barriers and topology
The use of segment protectors or field barriers protects the bus segment from short circuits in branch lines and provides the necessary protection type. However, the disadvantage of the usual four-channel field barriers is that they cannot be replaced in isolation in the event of a failure. Instead, in order to replace a single field barrier in the most commonly used line topology, the entire segment must be switched off. This has a detrimental effect on availability.
When it comes to field device connection, there is also a process-oriented requirement for non-electricians to carry out rapid replacement to keep any downtimes to an absolute minimum. This rapid replacement is achieved by means of connectors on the field device – normally M12 or 7/8 in. This sounds straightforward. However, the often harsh ambient conditions (ATEX, dust, acids, corrosive gases, etc.) make the use of connectors that can be assembled in the field largely impossible. The weak point here is the seal between the cable and connector.
As a result, when using connectors, connections that are firmly molded onto the cable and thereby permanently tight
are used. However, due to the often different distances between the field distributor and field devices, a whole range of cables assembled by the manufacturer in a variety of different lengths are needed. For economical reasons, it is not possible to keep such a number of different cables permanently available. The increased expense for warehousing and logistics would simply not be worthwhile.
Scalable field level
Phoenix Contact offers you a scalable field barrier installation concept which minimizes the effects of errors on a segment and thereby increases the availability of the system. Field barriers can be replaced during operation or the PROFIBUS PA/FOUNDATION Fieldbus can be expanded without negatively affecting communication with the remaining fieldbus devices.
This is possible thanks to the use of a DIN rail connector which is supplied as standard with each coupler. The connector ensures that the cross communication – such as that of a backplane – is not affected if an individual device coupler is removed. It can also be used to expand a segment without having a negative effect on the operation of the existing devices.
Not only can we provide you with all the necessary components such as device couplers, field barriers, surge protection, and fieldbus cables, we can also supply ready-to-install field connection boxes
These are either pre-assembled for your individual set-up or already prewired and equipped with all necessary field barriers. The field connection boxes are available for Ex and non-Ex installations and are supplied with all screw connections and cable clamp rails and busbars.
On the field device side, Phoenix Contact offers a small passive junction box which is mounted as a link just before the field device. It enables a field-compatible connection of the cable end of the drum goods from the field distributor with the open end of the assembled M12 cable to the field device.
The metal housing and the use of shield screw connections ensure a consistent fieldbus-compatible shield connection. In the housing, just the two fieldbus wires need to be connected. Its design as a simple item of electrical equipment in the color option blue means that is is also possible to use the field device junction box in intrinsically safe circuits up to Ex zone 1.