BASF uses innovative coupling relay

Relays and optocouplers at BASF in Ludwigshafen, Germany

In the coupling relay sector, the general opinion is that there are no real innovations emerging any more.

These rugged universal helpers, which are used in millions of industrial applications, are taken for granted. It is here that they perform their tasks between the controller and system almost invisibly: conditioning, electrically isolating, and multiplying signals.

However, new generation coupling relays can also reduce costs significantly. BASF in Ludwigshafen, Germany, uses an innovative relay and optocoupler system from Phoenix Contact.


Since the founding of BASF, the plant in Ludwigshafen has developed into the world's largest integrated chemical complex.

One example from the production spectrum is the vitamin factory in which fat-soluble vitamins A and E are manufactured. Almost all preliminary stages of the complex syntheses are generated on site and supplied via pipelines directly to the vitamin factory. The production processes are controlled by modern process control systems and the signal lines are routed via standardized routing frames.

Compact 6.2 mm coupling relays from the Phoenix Contact PLC-INTERFACE system are used to amplify signals for sensors. PLC-INTERFACE modules, which are the same shape, are used to condition feedback signals on the field side to the controller.


PLC-INTERFACE from Phoenix Contact  

PLC-INTERFACE from Phoenix Contact

The plug-in design of the relays and optocouplers is a particular advantage. Each channel can be optimally adapted to the application according to the voltage, power, and switching frequency.

If changing conditions mean that an optocoupler is required instead of a relay, the optocoupler can be connected at a later date and freely combined with the relay in just a few seconds without having to disconnect the wiring.

The products in the series, which come in all popular control voltages, are available with spring-cage or screw connection technology.

Useful accessories such as various bridges, partition plates, power terminal blocks, and device marking labels from Phoenix Contact's range of standard modular terminal blocks complete the system.


The PLC-INTERFACE system saves costs by reducing the total amount of space required, wiring effort, time, and assembly effort. This improves clarity and increases safety.

The key to this is the plug-in, vibration-resistant PLC bridge system. The safe isolation between input/output and the relay design with IP67 protection were two crucial deciding factors for BASF choosing PLC-INTERFACE from Phoenix Contact.

This is because safety has absolute priority in the chemical industry, whatever the cost.


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