11
Instructional Leaflet
IB2C12063H03
Effective March 2012
Instructions for Installation, Operation and
Maintenance of Magnum SB Insulated Case
Low Voltage Power Circuit Breakers
EATON CORPORATION
www.eaton.com
Circuit Breaker Inspection
All circuit breakers, once removed from their shipping
containers, should be visually inspected for any obvious
damage .
The current rating of the rating plug installed in the trip unit
should match the current rating of the sensors mounted on the
lower primary stabs of the circuit break er . Check to make sure
that this match exists . The rating plug rating can be viewed
from the front of the circuit breaker (
Figure 20
) . The sensor
rating can be viewed through the viewing windows at the rear
of the circuit breaker (
Figure 6
) . Sensors and rating plugs can
be easily changed as described in Section 6 .
Installing Drawout Circuit Breaker
In structures equipped for drawout circuit breakers, a bolted-
in cassette with movable extension rails supports the circuit
breaker (
Figures 5 and 7
) . The extension rails must first be
pulled all the way out . Once the rails are fully extended, the
circuit breaker can be carefully placed on the extension rails .
CAUTION
IT IS IMPORTANT TO TAKE GREAT CARE WHEN PLACING A
DRAWOUT CIRCUIT BREAKER ON ITS EXTENSION RAILS. IF THE
CIRCUIT BREAKER IS NOT PROPERLY SEATED ON THE EXTENSION
RAILS, IT COULD FALL FROM THE RAILS CAUSING EQUIPMENT
DAMAGE AND/OR BODILY INJURY.
Figure 6. Rear View Showing Current Sensor Rating Through
Viewing Window
Carefully lower the circuit breaker down onto the extension
rails . Be certain that the circuit breaker’s four molded drawout
rail supports are fully seated in the extension rail cutouts on
both sides (
Figure 7
) . Do not remove the lifting yoke from the
circuit breaker until it is properly seated on the rails .
Once the circuit breaker is on the extension rails and the lifting
yoke is removed, proceed with the rest of the circuit breaker
installation .
Rejection Interlocks
Within any one physical frame size Magnum type drawout
circuit breakers come in a variety of continuous current and
interruption ratings, some of which are incompatible with
others . Double wide circuit breakers also come with several
phase sequence options which are also incompatible . To
prevent the insertion of circuit breakers with (1) inadequate
interrupting capability, (2) with physically incompatible primary
disconnects or (3) with an incompatible phase sequence,
rejection interlock key plates are provided on both the circuit
breaker and cassette . The key plate on the circuit breaker is
pre-assembled at the factory; but the cassette-side rejection
plate and key pattern must be assembled and installed by the
switchboard builder .
Molded Rail
Supports
Extension Rail Cutout
Figure 7. One Side of Drawout Circuit Breaker Properly Seated on
Extension Rail
