47
10/09 AWB1230-1605
Effective October 2009
Operation and maintenance of
IZM low voltage air circuit breakers
MOELLER
www.moeller.net/de/support
CaUTiOn
TO PrEVEnT DaMagE TO THE raTing PLUg, DO nOT FOrCE iT inTO THE
MOUnTing CaViTY.
Use the same 1/8-inch screwdriver to tighten the M4 screw and
secure the rating plug in the trip unit. The maximum torque on the
mounting screw is 15 in-oz (0.1 Nm). Close the rating plug door.
Current sensor replacement
nOTiCE
rEMEMBEr THaT THE TriP UniT’S raTing PLUg anD THE CirCUiT
BrEakEr’S CUrrEnT SEnSOrS MUST HaVE MaTCHing raTingS.
The three current sensors are installed at the rear of the circuit
breaker on the lower terminals. A cover with sensor rating
viewing windows covers the sensors and is held in place with
screws (
). Remove the cover by removing the screws.
Figure 73. Current Sensor Cover in Place Over Sensors
Current Sensor Cover
If the circuit breaker is a drawout configuration, the lower primary
disconnect finger clusters and the vertical adapters must first be
removed from frame sizes up to 2500A. On the 3200A frame, both
the upper and lower primary disconnects and vertical adapters must
be removed. Each primary disconnect finger cluster is removed
by loosening the two hex-head bolts with a 10 mm wrench. These
bolts do not have to be completely removed to slide the primary
disconnects off of the terminals. Remove the vertical adapters next
from the circuit breaker terminals by removing the two or three
10 mm bolts holding them in place (
).
The current sensors are removed by pulling them off of the
terminals and unplugging the wiring plugs from the sensors
(
Install new current sensors by connecting the wiring plugs to the
sensors and sliding the sensors over the terminals. Reinstall the
cover over the sensors and secure in place with the screws
previously removed.
Reinstall the previously removed vertical adapters to the terminals
using the removed hardware and
40 ft-lb (55 Nm)
of tightening
torque. Make sure the vertical adapters are square to the rear
housing. Slip the primary disconnects on to the vertical adapters.
Make sure the primary disconnects are fully inserted on to the
vertical adapters. Tighten the two retention bolts to
40 in-oz (5 Nm)
of torque. Properly engaged and secured retention bolts should
engage the slots or holes in the vertical adapters.
Figure 74. One Current Sensor Shown Removed and
Disconnected
Current Sensor
Wiring Plug
Vertical Adapters
