New two-part surge protection system for signal lines

Modularity, loop disconnect function, and fault monitoring for signal lines up to SIL 3 in accordance with IEC/EN 61508 – these features are combined in the new M-LB-4000 surge protection system from Pepperl+Fuchs. The devices limit induced transients from different causes on signal lines, for example, due to lightning or switching operations. The two-channel modules support higher plant availability: Since the protective function is totally housed in the plug-in protection module, rewiring is unnecessary during the replacement.

The system comprises two-part surge protection and two-part fault status monitoring system.

The protection module comprises all protection components. It can be replaced without tools while the base module remains in operation. The device has a status indicator on the front panel. When pulling the protection module, the relevant signal circuit remains interconnected via the base module mounted on the DIN mounting rail. The disconnection process does not lead to any signal interruption, meaning that a protection module can be replaced without impairing plant operation.

The system allows easy commissioning and servicing utilising a loop-disconnect function and uninterrupted protection module replacement during ongoing operation.

If the protection module is rotated by 180° and plugged in, the integrated isolating function will break the signal circuit. This simplifies servicing work and loop checks and enables insulation tests to be performed during commissioning or repeated testing.

The two components of the fault status module monitor the status of multiple surge protection barriers. The kit consists of the optical emitter/receiver and the optical deflection unit. If a fault occurs in one of the barriers to be monitored, the optical signal is interrupted, and the fault is identified. The fault status module supplies an LED status indicator, allowing visual inspection of the surge protection to fulfil the normative necessities for regular testing. Also, a status message output is available, so that the block in which the fault occurred can be identified. One fault status module can monitor up to 50 modules.

At 6mm, the small width of the modules saves space in the switch cabinet. Existing common disconnect terminal blocks can be replaced during retrofitting regardless of space needs.