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differential protection trip

differential protection trip

differential protection trip

(OP)
hi..i have a situation here in my vessel..my 1 generator suddenly stop due to alarm " DIFFERENTIAL PROTECTION MAIN BREAKER CLOSE ..LIMIT 10% TIME 500ms"..i check the generator and found nothing..i changed some of the stuff like the differential relay board and the CT of the starpoint of the generator..but still this alarm is coming every time i parallel this gen to others..

thank you so much..

RE: differential protection trip

(OP)
i just want to ask some of your ideas what would be the cause of this and how would i know..its my first time to encounter such trouble..thank you..

RE: differential protection trip

When you parallel the generators, could the zero sequence current from one return via the neutral of the other? Given your differential protection, would this cause a trip?

RE: differential protection trip

Not if the CTs are properly placed and wired.

RE: differential protection trip

(OP)
i got 4 generators here of the same specs and everything..i exchanged some parts including the diff relay board and the ct..still i cant figure out what is the problem..the alarm still keep coming..is it possible that the problem lies with the main breaker?

RE: differential protection trip

Randomly exchanging parts is never a good strategy. What do the event reports from your differential relay show?

RE: differential protection trip

Far more likely it is a CT polarity problem, or perhaps a CT shorted or open circuit, based on what you have said so far.

Has the installation ever worked? If so, what happened when it stopped working?

Can you arrange to circulate a reasonable current in the main windings using a shorting link across the generator terminals and a vastly reduced field excitation? This would allow you to prove the scheme stability.

RE: differential protection trip

(OP)
thank you so much for the help and information..i finally figure out the problem of my system..it got something to do with the board which signals the MB to open...my system is working properly now..i really appreciate all your help and advice..thank you...[afro2]

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