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Magnum
1812.900A
53
7 TROUBLESHOOTING
7.1 Introduction
Table 7-1 will help to determine the probable causes of
simple circuit breaker problems and possible corrective
actions.
If problems cannot be resolved, contact the Eaton service
center for more in-depth assistance.
Table 7-1 Circuit Breaker Troubleshooting Guide (continued on next page)
Symptom
Probable Cause
Corrective Actions
Rating plug not installed and load current
through the breaker
Install rating plug that corresponds to current sensors
Repeated closing on transient (in-rush) current
with thermal memory active
Wait for circuit breaker (and loads) to cool before re-closing
The circuit breaker
trips
open (red fault trip indicator
button is
out
and/or fault indicator LED is
lighted
)
when closed on a load current
An overload or fault current condition
Use status and fault indicators to help locate and remove overload or fault
condition
Undervoltage release operates; voltage too
low or zero
Check and correct the UVR supply voltage (85-110% rated voltage)
Shunt trip operates
Check control signal(s) to shunt trip; correct if necessary
Circuit breaker
opens
(fault trip indicator button is
not
out)
Trip latch is defective
Inspect latch condition and engagement before closing; consult Eaton service
center
Shunt trip control signal absent or too low
Check supply voltage exceeds 70% of rated voltage when signal is applied to
shunt trip
Shunt trip is faulty or improperly installed
Remove front cover; check voltage supplied to shunt trip; make sure shunt
trip is seated and retainer snapped into place. Check for shunt trip motion;
replace shunt trip if faulty
Circuit breaker cannot be opened remotely, but can be
opened locally
Secondary contact wiring problem
Make sure electrical pin and socket connectors are properly seated in molded
plug. Verify proper wiring
Shunt trip control signal absent or too low
Check supply voltage exceeds 70% of rated voltage when signal is applied to
shunt trip
Shunt trip is faulty or improperly installed
Remove front cover; check voltage supplied to shunt trip; make sure shunt
trip is seated and retainer snapped into place. Check for shunt trip motion;
replace shunt trip if faulty
Circuit breaker cannot be opened remotely, but can be
opened locally
Secondary contact wiring problem
Make sure electrical pin and socket connectors are properly seated in molded
plug. Verify proper wiring
OPEN pushbutton locked
Remove lock
Circuit breaker cannot be opened locally
Faulty mechanism or main contacts welded
Contact Eaton service center
Closing spring not fully charged (check SPRING
CHARGED indicator)
Charge spring manually; check voltage to electrical operator; replace electrical
operator if faulty
If equipped with undervoltage release,
undervoltage release is not energized or is
faulty
Unplug undervoltage release from mounting deck and retry closing operation;
if OK, check voltage supply to undervoltage release (>85%); replace under-
voltage release if faulty
Circuit breaker locked in OPENposition
Check reason for lock
Drawout position interlock is operating;
levering screw
Make sure that circuit breaker is at a position that permits closure; door is
open
check that shutter (door) over the levering screw is fully closed
Circuit breaker makes no attempt to close with either
local (manual) or remote controls; springs do not
discharge
Circuit breaker interlocked with another circuit
breaker or device
Check for presence of an interlocking scheme (cable interlock or key
interlock); check to see if interlocked circuit breaker is CLOSED
Spring release (closing) coil supply voltage low
or spring release faulty
Check power supply voltage; replace spring release if faulty
Secondary contact wiring problem
Make sure electrical pin and socket connectors are properly seated in molded
plug. Verify proper wiring
Circuit breaker cannot be closed remotely (can be
closed locally)
Spring release closing coil signal blocked
Clear Digitrip 1150 relay contact
Circuit breaker cannot be closed locally (but can be
closed remotely)
Opening and/or closing pushbuttons locked
Check reason for lock
Charging motor supply voltage absent or too
low (<85%)
Check charging motor electrical circuit voltage (check under load)
Circuit breaker does not recharge electrically but will
recharge manually
Charging motor faulty
Replace charging motor assembly