Troubleshooting - GE AK-2-50 Maintenance Manual

GEK-7303 Low Voltage Power Circuit Breakers
6
TROUBLE
Overheating
Failure to Trip
AK-2
Breakers
Failure to Trip
AK-3 Breakers
False Tripping
AK-2 Breakers
False Tripping
AK-3 Breakers
Failure
.to
Close
and Latch
Burned Main
Contacts
TROUBLE SHOOTING
CAUSE
Contacts not aligned.
Contacts
dirty,
greasy or coated
with dark film;
Contacts
badly
burned or pitted.
Current-carrying surfaces
dirty.
Corrosive atmosphere.
Insufficient bus or cable capacity.
Bolts and nuts at terminal connections
uot tight.
Current in excess
of
breaker rating.
Excessive ambient temperature.
Inductive heating;
Travel of tripping device does not provide
positive release
gt
tripping latch.
Worn or damaged trip unit parts.
- Binds in overcurrent trip de.vice._
Loose or Disconnected Power Sensor
Disconnect Plugs.
Loose or Broken Power Sensor Coil
Tap Connections. -
Overcurrent pick up too low. _
Overcurrent time setti!)g too short.
Bind
in
overcurrent trip device.
Captive Thumb Screw on Power Sensor
Loose Fail-Safe Circuitry Reverts .
Characteristic to Minimum Setting
and Maximum Time Delay.
Tap Setting Dial on Power Supply
Incorrectly Set.
External Ground Sensor Coil
Improperly Connected.
Binding in attachments preventing
resetting
of
latch.
Latch out
of
adjustment.
Latch return spring too weak or broken.
Hardened or gummy lubricant.
Safety pin left in push rod.,
Motor burned out.
Faulty control circuit component.
Improper contact sequence
(main
contacts
not sufficienUy parted when arcing contacts
part). .
Short.circuit current leJel above inter-
rupting r.ating
of
breaker.
Loss
of
contact wipe or pressure.
· REMEDY
Adjust contacts.
Clean contacts.
Rep~ace contacts.
Clean surfaces
of
current-
carrying parta.
Relocate or proVide adequate
enclosure.
Increase capacity
of bus
or cable.
Tighten, but
do
not exceed, elastic
limit
of
bolts or fittings.
Check breaker application or modify
circuit
by
_ decreasing load. _
ProVide adequate venWation. -
C~rrect
bus
or· cable arrangement.
Re-adjust or_ replace tripping device.
Replace trip
unit.
Replace overcurrent trip device.
Tighten or Reconnect Disconnect .
Plugs.
Tighten or Reconnect Tap Connections. __
Check application
of
overeurrent
trip deVice. ·
Check appllcatiOn
of
overcurrent
trip deVice.
Replace overcurrent trip device.
Tighten Thumb Screw on Desired
Setting.
Set Dial
to
Correspond with Power
Sensor Coi! Tap.
Refer
to
Fig. 40 Page 38 for Pola_rity
and Connections. Check Continuity
of Shield and Conductors Connecting
the External Ground Sensor Coil
Re-align and adjust attachments.
Adjust
latch,
~eplace spring.
Clean bearing
and
latch surfaces,
Remove safety pin,
Replace
motor. ,. -
Replace or adjuat faulty device.
Increase arcing contact wipe. Adjuat
contact sequence
by raising or lower-
ing main
movable
contact
pivot
block.
ReQuires system study and possible
replacement
With
breaker
haVing
ade-
quate interrupting capacity.
Replace stationary contact springs
and dress.
up
or replace contacts. _