11 Troubleshooting
PXR Electronic trip unit
01/21 MN012005EN
www.eaton.com
159
11 Troubleshooting
The following table provides helpful information in the event of a fault.
Table 99: Possible faults, causes and solutions
Fault
Probable cause
Possible solution
The status LED of the trip unit
is not flashing.
No current is flowing through the current transformers of
the circuit breaker to the trip unit.
Connect the +24 V DC supply for auxiliary power and
monitor the status LED.
The circuit breaker will trip in
the event of a ground fault.
A ground fault is actually present.
Determine the location of the fault.
When using a 3-pole circuit breaker with ground-fault
protection in a four-wire system, the neutral current will
not be detected.
A 4-pole circuit breaker should therefore be used.
High inrush phase currents may cause the device to
temporarily detect a ground fault.
If zone selective interlocking is used, Z
out
to Z
in
should be
connected by means of a jumper to obtain a short delay.
section 4.10, “Zone selective interlocking (ZSI)”,
The trip unit is malfunctioning.
Replace the trip unit.
The breaker trips too quickly
in the event of a ground fault
or a short-time delay (zone
selective interlocking is not
used).
The ZSI function is active.
Make sure that the ZSI function in the settings menu is
turned off.
section 4.10, “Zone selective interlocking (ZSI)”,
The trip unit settings are incorrect.
Is the l
2
t slope or the “flat” option selected?
Change the ground fault or short-time delay settings.
The trip unit is malfunctioning.
Replace the trip unit.
The breaker trips too rapidly
on long delay.
The thermal memory is active.
In the event of repeated tripping, the thermal memory
protects the switch and any downstream system
components against overheating.
The trip unit settings are incorrect.
Change the long-delay settings.
The primary source of
injection current is not
supplying the correct current.
The testing of the primary injection and the trip times
yields incorrect results.
Use an oscilloscope with a current probe to determine the
exact current value and times, and to ensure that no inrush
current peaks will occur.
Single-phase testing.
When testing a single phase, the current may “bleed” into
other de-energized phases and thereby reduce the testing
phase current itself.
During testing with high current pulses, an overload trip
may occur due to the cumulative effect of the short-
current pulses.
Deactivate the thermal memory for the duration of the test.
Reactivate the memory again once the test has been
completed!
The precise input levels are difficult to control and
reproduce when testing the primary injection at high
current levels.
Use functional current testing (remote) via USB/PXPM.
The LCD display is not
connected to the power
supply.
No auxiliary power (24 V DC) will be available if the
current flowing through the circuit breaker is less than the
minimum current required for the operation of the LCD
display.
Connect the auxiliary power supply.
The status LED is
permanently red or flashes
red.
The circuit breaker locking mechanism is not closing
properly.
Contact your Eaton representative for manufacturer support.
Internal memory issue.
Contact your Eaton representative for manufacturer support.
The maintenance mode fails
to deactivate.
Faulty remote or local switch.
Make sure that the local or remote switch is not turned on.
The maintenance mode was originally activated via the
communication interface, which is currently not available.
If possible, restore the communication link and check for
possible wiring errors.
