Trip Circuit Monitoring (a.k.a. Supervision)

© Copyright 2012 Rod Hughes Consulting Pty Ltd

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TCS, or rather TCM as referred to in IEEE C37.2, is a common requirement for increasing overall confidence in the reliability of a tripping circuit.

Wiring of the TCM is important to make sure that all possible tripping circuits are covered.  Applying TCM as part of "any" IED in the system may not give you full coverage if there are other IEDs that may also be required to trip the CB.

In the case of TCM schemes based on opto inputs, the vendors usually have some example schemes in their instruction manuals.

But be careful!

Some vendor diagrams are wrong and dangerous when used with multiple tripping contacts in parallel ☹

This PDF shows the correct wiring for multiple tripping IEDs and the positioning of the TCS function at the "bottom" of the chain of protection contacts.

A more extensive review of TCS is provided here:  

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