Transformer Differential Protection trip Fault
Transformer Differential Protection trip Fault
(OP)
Hello
Step-down transformer (20kv /6.6KV ) 22MVA CT ration 2000/1, was tripped by (Sepam 2000) differential Protection Unit .
I've measured the Transformer insulation resistance for both primary and secondary side ,all results was great 7 G-ohm.
I've primary injected current in CTs ,all CT secondary currents was correct as ratio .
IF i have restored the Transformer with out load it keeps energized with out trip .
If I have restored the Transformer with load it take 1day and trip by differential unit .
what would the problem be? How can I full be sure the CT are okay ?
Step-down transformer (20kv /6.6KV ) 22MVA CT ration 2000/1, was tripped by (Sepam 2000) differential Protection Unit .
I've measured the Transformer insulation resistance for both primary and secondary side ,all results was great 7 G-ohm.
I've primary injected current in CTs ,all CT secondary currents was correct as ratio .
IF i have restored the Transformer with out load it keeps energized with out trip .
If I have restored the Transformer with load it take 1day and trip by differential unit .
what would the problem be? How can I full be sure the CT are okay ?
Emad Shaaban
Tripoli Libya






RE: Transformer Differential Protection trip Fault
RE: Transformer Differential Protection trip Fault
http://notronco.com/dnl/catalogue/schneider/MGC/AC...
RE: Transformer Differential Protection trip Fault
If the event records don't turn up anything too suspicious, that's where I'd look first.
RE: Transformer Differential Protection trip Fault
RE: Transformer Differential Protection trip Fault
thank you for your instruction ,
the transformer had been in service since 2004 . I am not sure a bout the CTs although I make current injection to check the ration ,I want to be sure 100% that CTs are okay ,what other tests that I can do (like saturation test!!)?
Emad Shaaban
Tripoli Libya
RE: Transformer Differential Protection trip Fault
RE: Transformer Differential Protection trip Fault
I have seen improperly set up relays stay in service for years before a misoperation caused an investigation that located problems.
old field guy
RE: Transformer Differential Protection trip Fault
RE: Transformer Differential Protection trip Fault
Comtrade file ans event list from relay are needed
Transformer in operation 12 years, Im not believe in some mistakes.
Please make stability test with 400V. or disconnect trip from 87T and check stability with load
From my point of view it is some problem with CT wiring, some bad connection.