A non magnetic metal disc
can rotate in a magnetic field between two electro magnets. The disc is
restrained by a coil spring. The flux produces a torque on the side which
rotates the trip lever away from the trip contacts.
In reverse power conditions
the flux from the voltage coil and current coil interact to rotate the disc in
the reverse direction. The amount of torque/current (and hence power) is set on
the current coil tapping.
A permanent magnet is
provided on the disc to provide damping. A 3 to 5second delay is incorporated
into the trip circuit to allow for transients when paralleling.
D.C
1. Low voltage coil
2. Overcurrent trip
3. Reverse current trip
4. Reverse current
trip
2a and 2b are fitted in case
of circulating current via the equalising connection.
Under normal running , fields of '3' and '4' act
together to hold the trip contact down. With reverse current fields are in
opposition and a spring pushes the plunger against a trip bar to open the
reverse current trip relay
REVERSE POWER TRIPPING
Reviewed by HODO
on
September 22, 2017
Rating: