Answer Posted / er. avijit dixit
NGR means neutral grounding resistors....it is just used for
the purpose of solidly grounding arrangement of star
connected 3.3 kv to more stator winding of alternator. NGR
IS USED WITH A HIGH RESISTANCE FOR ABOUT 65.5 OHMS IN FOUR
PARTS MEANS 63.5*4 IS THE TOTAL VALUE. IT LIMITS THE NEUTRAL
CURRENT UP TO THE SPECIFIED CT RATIO AND ALSO PROVIDES A
DIFFERENTIAL PROTECTION TO THE STATOR WINDINGS OF
ALTERNATOR. NGR IS ALSO USED TO PREVENTS THE EARTH LEAKAGE
STRAY CAPACITANCE AND STOPS THE REVERSE SURGES. IT PROVIDES
PROTECTION TO THE PROTECTIVE CTS AND PTS AGAINST HEAVY
EARTH CURRENT FLOW DURING STABILITY LOOSE.
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