Testing Magnetic Coils; Replacement Of Power Sensor Components - GE AK-2-50 Maintenance Manual

Low Voltage Power Circuit Breakers GEK-7303
Fig. 33 (8039646) Magnetic Coil Assembly for AK-3 75, 100 Breakers (Only)
· (Mounted on Assembly Fixture) ·
. 1 • . Power Sensor Coil Assembly
2. Transformer Taps in Ampere
3 •. Disconnect Plug
to either terminal· at · remote C. T. and check to
assure the shield is continuous from Power Sensor
Plug .. to remote C.T. by checking for continuity
between R and A.
If
continuity does not now
exist, shield is not continuous and the point of
discontinuity must be found~ Check the control
disconnect as the possible point of discontinuity.
Remove. jumper at remote C.T. after_shield c;:on:.
tinuity is establi~~ed. · ·
Note the po_ l arity marks on the grounc!_sensors. ~e
sure the external ground C. T. senses the neutral
current associated with the particular breaker
load current and that polarity marks are in ac-
cordance with Fig. 40.
If
the breakerbottom studs
connect to the source, the external C.T. must also
· have its polarity ~,;irk toward the source.
TESTI N ~ _ MAGNETI C COILS
After the PST-1 Test Kit has been used to deter-
mine the adequacy of perf~rmance o! t1?e Power
. Sensor Unit and the .Power SUpply Unit, it may be
advisable or required to test the magnetic coils by
the use of a Hi-current- Low voltage type test set.
In this event·on1y one-test per phase need be made.
This test should be made at· s ome convenient multi-
ple of pick- up · setting such as 3 X current setting for
comparison with published time- current curves.
In the event the breaker is equipped with ground
sensor, the ground sensor will cause tripping on
single pole testing unless the signal is short.ed
at the terminal board Fig. (40). Short point
4. Terminal Board
5. External Ground Sensor
Lead
1 and 5 during overcurrent test.
.
.
The above considerations should indicate which of ·
the· four major components is faulty and in need
of replacement.
REPLACEMENT OF POWER - SENSO R
COMPONENTS .
Power Sensor Unit "(Fig~ 35)
1. _ Loosen screw·
connecting the uni~ tq
th_ e
front frame. ·
2. Slide unit forward.
3 • . Remove control plug by alternately loosen-:
- ing th~ two retaining screws.
4. Replace in reverse order.
Trip Solenoid (Fig. 36)
1. Remove. opening springs
2. Raise cross bar to gain additional access
room
3, Remove two nuts holding device to bracket
4. Remove wiring cleats and connections to
terminal board on Power Supply to free the · trip
solenoid for removal