57
Section 8: Troubleshooting
Series NRX with PXR - type RF low voltage power (air) circuit breakers instruction manual
MN013002ENH03 September 2016 www.eaton.com
Table 7. Circuit breaker troubleshooting guide.
Symptom
Probable cause
Corrective action
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
Repeated closing on transient (in-rush) current with
thermal memory active
Wait for circuit breaker (and loads) to cool before
reclosing
An overload or fault current condition
Use status and fault indicators to help locate and
remove overload or fault condition
Circuit breaker opens (fault trip indicator but-
ton is not out)
Undervoltage release operates; voltage too low or
zero
Check and correct the UVR supply voltage (85–110%
rated voltage)
Shunt trip opens
Check control signal(s) to shunt trip; correct if neces-
sary
Trip latch is defective
Inspect latch condition and engagement before clos-
ing; consult Eaton
Circuit breaker cannot be opened remotely,
but can be opened locally
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
Check voltage supplied to shunt trip; make sure ST is
seated in its tray; check for ST motion; replace ST if
faulty
Secondary wiring problem
Make sure electrical connections are properly made
and verify proper wiring
Circuit breaker cannot be opened locally
OPEN pushbutton locked
Remove lock
Faulty mechanism or main contacts welded
Contact Eaton
Circuit breaker makes no attempt to close
with either local (manual) or remote controls;
springs do not discharge
Closing spring not fully charged (check SPRING
CHARGED indicator)
Charge spring manually; check voltage to electrical
operator; replace operator if faulty
If equipped with undervoltage release, undervoltage
release is not energized or is faulty
Remove left accessory tray containing UVR and retry
closing operation; if OK, check voltage supply to UVR
(>85%); replace UVR if faulty
Circuit breaker locked in OPEN position
Check reason for lock
Drawout position interlock is operating; levering
screw
Make sure circuit breaker is at a position that permits
closure; check that shutter door over levering screw is
fully closed
Circuit breaker interlocked with another circuit
breaker or device
Check for presence of an interlocking scheme (cable
or key); check to see if interlocked circuit breaker is
CLOSED
Circuit breaker can’t be closed remotely (can
be closed locally)
Spring release (closing) coil supply voltage low or SR
faulty
Check power supply voltage; replace spring release if
faulty
Secondary contact wiring problem
Make sure electrical connections are properly made
and verify proper wiring
Circuit breaker can’t be closed locally (can be
closed remotely)
Opening and/or closing pushbuttons locked
Check reason for lock
Circuit breaker does not recharge electrically
but will recharge manually
Charging motor supply voltage absent or too low
(<85%)
Check charging motor electrical circuit voltage (under
load)
Charging motor faulty
Replace motor assembly
Drawout circuit breaker will not lever in
Cell rejection code plate
Breaker rating not compatible with cassette require-
ment
Levering-in screw not fully in DISCONNECT position
at insertion
Rotate levering handle counterclockwise to
DISCONNECT position, then insert circuit breaker fully
into cassette
Circuit breaker not pushed into cassette far enough
Push circuit breaker in as far as possible
Protective shutters jammed/locked
Clear problem
Position detent is engaged
Reset detent system
