Position the trip unit in the base. Make sure the latch
bracket pin is properly seated in the slots in the sideplates
(Figure 3-2). If necessary, move the handle toward the
line end of the circuit breaker to seat the trip unit.
Screw in and tighten three trip unit retaining screws
(center first). Torque to 12 Ib-ft (16.27 N.m). Make sure
the holes in the trip unit conductors line up with the
tapped holes of the frame load conductors for proper
terminal installation.
DO NOT EXCEED A TORQUE OF 12 LB-FT (16.27
N.M). EXCESSIVE TORQUING WILL SHEAR
SCREWS. FAILURE TO APPLY THE REQUIRED
TORQUE MAY LEAD TO EXCESSIVE HEATING AND
CAUSE NUISANCE TRIPPING OF THE BREAKER.
If a standard “L” frame internal accessory is to be
installed in the right pole, cut the cable tie on wire-
retaining bracket and discard the bracket. Install the
attachment according to the individual accessory
instruction leaflet, and attach the wires that were
attached to the wire-retaining bracket to the attachment
mount bracket with a cable tie.
I.L. 29C508B
Page 3
Effective 9/00
Install the wire retaining bracket into the right pole trip
unit accessory retaining slots. For ground fault or
ground fault alarm trip units route the white and gray
wires out the frame accessory wiring channels.
Ground fault trip units are supplied from the factory with
a wire harness with pigtail lead connections for a neutral
current sensor (white and gray wires). A neutral current
sensor is provided with each trip unit.
Install the jumper plug assembly into the trip unit (see
Figure 3-2) with the keying pin in the bottom right corner.
Note: Jumper plug assembly fits in one orientation only.
Digitrip OPTIM 550 Ground Fault Trip Units detect
ground fault currents through Residual Sensing. They
are not designed to use source ground or zero
sequence ground fault sensing methods. If the system
neutral is grounded, but no phase to neutral loads are
used, the neutral current sensor is not necessary. In that
case, the white and gray leads on the trip unit should be
cut off before installation.
If the system neutral is grounded and phase to neutral
loads are used, then the neutral current sensor must be
used(Figure 3-3). It should be connected to the breaker
according the diagram in Figure 3-4. It has the same
turns ratio as the phase current sensors in the trip unit.
!
CAUTION
Figure 3-2 Trip Unit Installed in Circuit Breaker
Sideplate
(Both Sides)
Latch Pin
Trip Unit
Retaining
Screws
(Both Sides)
Interphase
Barriers
(Both Sides)
Accessory
Retaining Slot
(Both Sides)
Frame Accessory
Wiring Chanels
Orientation
Keying Pin
Jumper Plug
Assembly
Trip Unit Conductor
and Frame Load Conductor
Tapped Holes
for Terminals
Wire-Retaining
Bracket
