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Reply To: Protection Riddle No.44 – Bad designing of protection circuit and disastrous accident in power plant

#1689
Scoota

    Answer #3 is correct as this scheme does not initiate a trip during interruptions to 110VDC tripping supply. Also it is bad practise to utilise only an AC lube oil pump. I usually see a DC lube oil pump fed from a battery supply. In the event the AC LO pump fails the turbine is tripped and the DC lube oil pump starts up to provide lubrication during run down of the turbine.