One of our gas turbine generator unit "1st stage rotor
ground fault" alarm was occured several times. we tried to
measure some voltage vulue ground fault protection relay
(UNS3020a made by ABB and we measured the value of:
Ground: 0.9VDC
5V: 5.8VDC
24V: 23VDC
u+: 300 – 350mVAC
Rf1: 17.5mVAC
Rf2: 17.6mVAC
The unit still running and the alarm was reset. As of 6pm
yesterday and unitl now no alarm happened again. I our
protection relay was defective?
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Answer Posted / yvb
Stage 1 Alarm is only Alarm...Stage II is trip..so your
system working Ok...
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