Answer / santosh kawade

Rotar earth fault protection for generator (hydro or
thermal same scheme):

Rotar earth fault protection contains two stages 1st stage
earth fault protection and 2nd stage earth fault
protection.

As per scheme in normal running condition rotar core is
connected to rotar winding through a resistance bridge, as
soon as 1st stage rotar earth fault occur it gives alarm.

Then for 2nd stage rotar core is connected to ground
through a bridge and when 2nd stage rotar earth fault occur
it gives trip command to generator.

(Rotar connection to ground/winding is through a slip-ring
and brush system connected at one end of rotar.)

Santosh Kawade
9224 69 3116

Answer / siva

dc field flashing:to build up a voltage in a generator
residual flux is necessary. it is from the property of
retentivity of magnet. if it is absent we have to provide
the flux by a low voltage battery.this phenomena of
providing field flux(residual flux)by an external battery is
field flashing especially in dc shunt generator

where AVR is connected in power plant.

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