What is fail-safe design of switchgear control and relaying
What is fail-safe design of switchgear control and relaying
(OP)
Gentlemen,
What is the practice of fail-safe design of switchgear control and relaying? To be fail-safe, shall all dry-contacts be normally closed for interlock and intertripping? Shall all CBs be tripped when control power fails?
Is there any documentation regarding fail-safe?
Thanks,
Paul2gh
What is the practice of fail-safe design of switchgear control and relaying? To be fail-safe, shall all dry-contacts be normally closed for interlock and intertripping? Shall all CBs be tripped when control power fails?
Is there any documentation regarding fail-safe?
Thanks,
Paul2gh






RE: What is fail-safe design of switchgear control and relaying
Im not sure if possible found some documentation on the issue.
From practic, interlockings used with NC contacts ( possible with NO contacts too), relaying with NO contacts ONLY.
In some very critical systems used NV( No Voltage release for the CB with mechanical trip ), for example: MV motors, infeeds, but of course not all CB's.
Hope it help.
Best Regards.
Slava
RE: What is fail-safe design of switchgear control and relaying
RE: What is fail-safe design of switchgear control and relaying
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If we learn from our mistakes I'm getting a great education!
RE: What is fail-safe design of switchgear control and relaying
If you're worried about the control of your electrical system, then the idea (and costs) of redundant tripping supplies is a consideration but you will also need to deal with the process people as to what has to stay powered up for safety considerations. In my facility we have emergency power buses to care for critical valving and control functions. It gets to be a pretty involved discussion and is one that needs to take place early in the design process.
old field guy