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Appendix B Troubleshooting Guide
Symptom
Unit status LED is not blinking
Unit Status LED is steady on
As soon as current starts to
flow through the breaker, it
trips and the Instantaneous
trip LED comes on
LED does not come on when
battery check button is
pressed
Breaker trips on ground fault
Breaker trips too rapidly on
ground fault or short delay
(Zone Selective Interlocking
not used)
Breaker trips too rapidly on
long delay
Probable Cause
Current through breaker is
<25% of sensor rating
Trip unit is malfunctioning
Light loading
Trip unit is malfunctioning.
Rating plug is not installed or
is loose
Rating plug is open internally
Trip unit is malfunctioning
Battery installed backwards
Dead battery
Trip unit is malfunctioning
There actually is a ground
fault
CH Type-V current sensors in
one or more phases have
incorrect polarity
Trip unit is malfunctioning
High inrush phase currents
may cause fictitious ground
pickup momentarily
Connection from Zout to Zin is
missing
Trip unit settings are not
correct
Trip unit is malfunctioning
Long Time Memory selected
Trip unit settings are not
correct
Possible Solution(s)
No problem. Status LED will
not operate with breaker
currents <25% of sensor
rating
Replace trip unit
No problem. Unit Status LED
will not flash until 25% of
sensor rating
Replace trip unit
Install rating plug and/or
check for loose connections
Replace rating plug
Replace trip unit.
Install correctly
Replace battery
Replace trip unit
Find location of the fault
Verify circuit breaker wiring
Replace trip unit
Connect Zout to Zin jumper to
provide some time delay
Make connections B8 to B9
Change settings
Replace trip unit.
Turn off Long Time Memory
Change settings. Long Time
Delay setting is based on 6 × Ir
I.L. 66A7534H04
References
See Note in Section 3.2
Refer to Appendix C
See Caution in Section 3.3
Refer to Appendix A
Refer to Section 4.3
Effective 8/2006
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