42
PT UNIT USER MANUAL
APRIL 2023 www.eaton.com.cn
Appendix B - Troubleshooting
Symptom
Probable Cause
Possible Solutions
Reference
The Trip Unit Status LED is not blinking.
Current is not flowing through the circuit
breaker sensors to the trip unit.
C24 Vdc and ground of auxiliary
power to circuit breaker terminals 19
and 20 and observe the status LED.
Breaker trips and reports ground fault.
There actually is a ground fault.
Find the location of the fault.
In three-pole, four-wire residual sys-
tems, the neutral current sensor may
not have the correct ratio or be properly
connected.
Check the ground fault setting is residual
or source/zero ground. Check and make
sure that the connections from the
neutral current sensor to the breaker are
not reversed.
See Sections 4.4 - 4.5: Ground Fault
Settings and Ground Fault Sensing.
High inrush phase currents may cause
fictitious ground pickup momentarily.
If the zone selective interlocking (ZSI)
function is employed, connect a jumper
from Zin to Zout to provide some time
delay.
See Section 4.9:
Zone Selective Interlocking.
The trip unit is malfunctioning.
Replace the trip unit.
Breaker trips too rapidly on ground fault
or short delay (zone selective interlocking
not used).
ZSI function is ON.
Check whether the ZSI setting in the
Setting menu is OFF.
See Section 4.9:
Zone Selective Interlocking.
The trip unit settings are not correct. Is
I
2
t Slope or Flat selected?
Change the Ground Fault or Short Delay
Times Settings.
See Section 4.2: Short Delay Pickup
Settings. See Sections 4.4 -4.5: Ground
Fault Settings and Ground Fault Sensing.
The trip unit is malfunctioning.
Replace the trip unit.
The breaker trips too rapidly and reports
long delay fault.
Long Time Thermal Memory Function is
selected.
Disable the Long Time Thermal Memory
for Long Delay Times setting.
See Section 4.1: Long Delay Pickup and
Time Setting.
The trip unit settings are not correct.
Change the Long Delay settings.
See Section 4.1: Long Delay Pickup and
Time Setting.
The primary injection current source is
not putting out the correct current.
Primary injection testing pickup and trip
times are not correct.
Use an oscilloscope with a current probe
to accurately verify current val-ues,
times, and that there are no inrush
spikes of current observed.
Single Phase Testing.
When testing single phase, the current
can “bleed” into other un-energized
phases and reduce the value of current
in the testing phase.
It is possible, when using the high cur-
rent “pulse” testing technique, to cre-ate
a long time thermal memory trip as a
result of the cumulative action of the
short duration currents.
Disable the Long Time Thermal Memory
feature for Long Delay Time setting.
See Section 4.1: Long Delay Pickup and
Time Setting.
Precise pickup levels are difficult to
control and repeat for primary injection
testers as high current levels.
Use functional current testing (remote)
via USB/PTM.
See Section 8.2: Functional Current
Testing (Remote) via USB/ PTM.
See Section 3.3: Pickup/Cause of Trip
Indicators.
Cause of Trip LEDs are blinking and
breaker is closed.
The trip unit was not reset from a
previous event.
Depress the Reset pushbutton to clear
the LED or test flashing.
The battery voltage is too low to reset the
latch circuit on the cause of trip LEDs.
Replace the battery.
See Section 9.1: Replacing the Battery.
Appendix B - Troubleshooting
Table B1. Troubleshooting
