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7. Maintaining the PXR trip unit
Power XPert® release triP unit for MagnuM PXr circuit breakers
MN013015EN January 2022 www.eaton.com
7.2 Replacing the trip unit
The PXR trip unit is designed as a field replaceable unit.
The breaker must be in the open position to replace the trip
unit. There is an interlock that will cause the breaker to open
in you attempt to remove the trip unit while the breaker is
closed.
Before replacing the trip unit, record the position of the
setting dials for the PXR 20. It may be convenient to use
PXPM to save or print all the settings for validation with the
new trip unit after replacement.
The frame module retains the circuit breaker’s configuration,
the primary and enhanced protection settings, relay configu-
ration, and Modbus configuration. They will be restored into
the new trip unit except for the rotary switch settings of the
PXR 20 which must be set manually.
Remove the circuit breaker from service.
1. Remove all control power from the breaker and
remove any connected USB cable. The trip unit must
not be powered during removal or installation.
2. Remove the circuit breaker front cover. Then remove
the trip unit from the circuit breaker’s frame rating
module using the following steps:
•
Break the factory seal.
•
Then use a screwdriver to loosen the top and
bottom screws.
Note that the bottom screw is located left of the USB
port and covered by the door.
Figure 23. Removing the ETU.
3. Pull the unit outward to disengage the molded,
40-pin connector from the frame module printed
circuit board and the small 10-pin connector from the
voltage divider board (PXR 25). The 18-pin wiring
connector at the top of the trip unit is keyed (arrows
in Figure 24) and has locking tabs on the sides (circled
in the Figure 24). Squeeze the locking tabs inward
and gently disengage the connector.
Figure 24. Installing the ETU wire harness.
4. To install the new trip unit, first connect the wiring
harness at the top of the trip unit. It is a keyed
connector and you should hear a slight click as the
locking tabs engage. Then, to mount the trip unit,
align it with the guides of the frame module. Keep it
parallel with the receiving, molded housing.
5. Use caution to ensure that the interlock that prevents
the breaker from closing if the trip unit is removed is
engaged with the boss on the side of the housing and
is being depressed. Press the trip unit into the circuit
breaker until the trip unit seats firmly into the receiv-
ing housing. Secure it in place with the two screws
supplied.
6. Replace the circuit breaker front cover.
7. Set the rotary settings switches if using a PXR 20 and
validate your settings using your records or PXPM.
8. Restore control power if available. A secondary
injection test is recommended before placing the
circuit breaker back into service. See Section 6.4.1 -
Secondary injection test.
9. Restore the circuit breaker to service.
7.3 Replacing the battery
The battery is provided to maintain the LED indication of the
cause of the trip and the real time clock. A battery icon at
the bottom of the display indicates remaining battery life.
The battery plays no part in the protection function of the trip
system. The battery can be replaced at any time, including
while the circuit breaker is in-service, without affecting the
operation of the circuit breaker or its protection functions.
On the initial installation of the circuit breaker, remove and
discard the insulating tab and then re-insert the battery tray.
Press the reset push button to extinguish any cause of trip
LEDs which may illuminate when the battery is inserted.
