Section 7: Troubleshooting; Table 7. Circuit Breaker Troubleshooting Guide - Eaton NRX Series User Manual

Series NRX Low Voltage Power (Air)
Circuit Breakers User Manual

Section 7: Troubleshooting

Introduction
Table 7 will help to determine the probable causes of simple circuit
breaker problems and possible corrective actions. Possible problems
associated with the electronic trip unit are covered in a companion

Table 7. Circuit Breaker Troubleshooting Guide

Symptom
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
Circuit breaker opens (fault trip indicator button is
not out)
Circuit breaker cannot be opened remotely, but can
be opened locally
Circuit breaker cannot be opened locally
Circuit breaker makes no attempt to close with either
local (manual) or remote controls; springs do
not discharge
Circuit breaker can't be closed remotely (can be
closed locally)
Circuit breaker can't be closed locally (can be closed
remotely)
Circuit breaker does not recharge electrically but will
recharge manually
Drawout circuit breaker will not lever in
General
Probable Cause
Rating plug not installed and load current through the
breaker
Repeated closing on transient (in-rush) current with thermal
memory active
An overload or fault current condition
Undervoltage release operates; voltage too low or zero
Shunt trip opens
Trip latch is defective
Shunt trip control signal absent or too low
Shunt trip is faulty or improperly installed
Secondary wiring problem
OPEN pushbutton locked
Faulty mechanism or main contacts welded
Closing spring not fully charged (check SPRING CHARGED
indicator)
If equipped with undervoltage release, undervoltage
release is not energized or is faulty
Circuit breaker locked in OPEN position
Drawout position interlock is operating; levering screw
Circuit breaker interlocked with another circuit breaker or
device
Spring release (closing) coil supply voltage low or SR faulty
Secondary contact wiring problem
Spring release closing coil signal blocked
Opening and/or closing pushbuttons locked
Charging motor supply voltage absent or too low (<85%)
Charging motor faulty
Cell rejection code plate
Levering-in screw not fully in DISCONNECT position at
insertion
Circuit breaker not pushed into cassette far enough
Protective shutters jammed/locked
Position detent is engaged
Instructional Book
publication, IL01301051E (Digitrip 520) or IL01301064E (Digitrip 1150).
If the problem cannot be resolved with the aid of one or both of these
guides, contact the Eaton service center for more in-depth assistance.
Corrective Action
Install appropriate rating plug compatible with frame rating module
Wait for circuit breaker (and loads) to cool before reclosing
Use status and fault indicators to help locate and remove overload or fault
condition
Check and correct the UVR supply voltage (85–110% rated voltage)
Check control signal(s) to shunt trip; correct if necessary
Inspect latch condition and engagement before closing; consult Eaton
Check supply voltage exceeds 70% of rated voltage when signal is applied to
shunt trip
Check voltage supplied to shunt trip; make sure ST is seated in its tray; check
for ST motion; replace ST if faulty
Make sure electrical connections are properly made and verify proper wiring
Remove lock
Contact Eaton
Charge spring manually; check voltage to electrical operator; replace operator
if faulty
Remove left accessory tray containing UVR and retry closing operation; if OK,
check voltage supply to UVR (>85%); replace UVR if faulty
Check reason for lock
Make sure circuit breaker is at a position that permits closure; check that
shutter door over levering screw is fully closed
Check for presence of an interlocking scheme (cable or key); check to see if
interlocked circuit breaker is CLOSED
Check power supply voltage; replace spring release if faulty
Make sure electrical connections are properly made and verify proper wiring
Clear Digitrip 1150 relay contact
Check reason for lock
Check charging motor electrical circuit voltage (under load)
Replace motor assembly
Breaker rating not compatible with cassette requirement
Rotate levering handle counterclockwise to DISCONNECT position,
then insert circuit breaker fully into cassette
Push circuit breaker in as far as possible
Clear problem
Reset detent system
EATON CORPORATION www.eaton.com
MN01301003E
Effective July 2011
47