| Rod Hughes Consulting General Web Site | Applications Home | Innovations and Solutions Home | A bit about Rod Hughes |
|
|---|
Note - if the navigation pane on the left of this window is not visible, click the 2-pane icon on the top bar
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.
There are "degrees" of trip circuit monitoring:
- tripping voltage is healthy
- trip wiring is operational whilst circuit breaker is closed
- trip wiring is healthy prior to closing
- combinations of the above
A faulty Trip Circuit is potentially a disaster waiting to happen .. hence it is important to have confidence that tripping will work BEFORE closing the circuit breaker AS WELL AS whilst it is closed.
The trip circuit can become faulty for a variety of reasons:
- rodent eating through wires
- trip supply failure
- circuit breaker trip coil open circuit
- faulty circuit breaker auxiliary contacts not changing to correct positions
- isolating links left open
None of these are self-evident until there is a real power system fault necessitating a trip , or at the next maintenance program.
If you close with it faulty, you can't trip when a power system fault actually occurs or even just as a controlled manual opening !
If it fails whilst the CB is closed, an alarm can be raised to prompt early intervention prior to the next power system event.
In either case, that may necessitate isolating the particular circuit breaker on both sides by opening multiple other circuit breakers until the problem is corrected.
It is to note that TCM does not monitor the operation of the protection device contact itself. This can only be done with physical device testing.
However, the detailed wiring diagram to the TCM is CRITCIAL to make sure that all possible tripping circuits and associated wiring are covered.
Applying TCM as part of "just 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 which offer various features and advantages, but the overall principle is the same:
TCM uses a continuous, but small "trickle" current (well below the circuit breaker trip coil minimum operating current) passing trough the trip circuit wiring to and from the protection relays and through the trip coil to prove a continuous circuit..
Of course this also requires some "fail safe" considerations of a failure or problem in the TCM circuitry itself to prevent an inadvertent trip of the circuit breaker.
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:
Contact Me
A phone call is nearly always welcome depending on the time of night wherever I am in the world.
Based in Adelaide UTC +9:30 hours e.g.
| April-September | Noon UK = 2030 Adelaide |
| October-March: | Noon UK = 2230 Adelaide |
Office + 61 8 7127 6357
Mobile + 61 419 845 253
Extra Notes:
No Waiver, No Licence:
Rod Hughes Consulting Pty Ltd accepts no direct nor consequential liability in any manner whatsoever to any party whosoever who may rely on or reference the information contained in these pages. Information contained in these pages is provided as general reference only without any specific relevance to any particular intended or actual reference to or use of this information. Any person or organisation making reference to or use of this information is at their sole responsibility under their own skill and judgement.
This page is protected by Copyright ©
Beyond referring to the web link of the material and whilst the information herein is accessible "via the web", Rod Hughes Consulting Pty Ltd grants no waiver of Copyright nor grants any licence to any extent to any party in relation to this information for use, copy, storing or redistribution of this material in any form in whole or in part without written consent of Rod Hughes Consulting Pty Ltd.