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Instruction Book
Page 6
Effective: May 2006
2-5 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 rat-
ing plug rating can be viewed from the front of the circuit
breaker (Figure 3-4). The sensor rating can be viewed
through the viewing windows at the rear of the circuit
breaker (Figure 2-3). Sensors and rating plugs can be
easily changed as described in Section 6.
2-6 INSTALLING DRAWOUT CIRCUIT BREAKER
In structures equipped for drawout circuit breakers, a
bolted-in cassette with movable extension rails supports
the circuit breaker (Figures 2-2 and 2-4). 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
Figure 2-3 Rear View Showing Current Sensor Rating
Through Viewing Window
For more information visit: www.EatonElectrical.com
NOT PROPERLY SEATED ON THE EXTENSION
RAILS, IT COULD FALL FROM THE RAILS CAUSING
EQUIPMENT DAMAGE AND/OR BODILY INJURY.
Carefully lower the circuit breaker down onto the exten-
sion rails. Be certain that the circuit breaker's four mold-
ed drawout rail supports are fully seated in the exten-
sion rail cutouts on both sides (Figure 2-4). 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 cir-
cuit breaker installation.
2-6.1 REJECTION INTERLOCKS
Within any one physical frame size Magnum type dra-
wout 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 cir-
cuit 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 cas-
sette-side rejection plate and key pattern must be
assembled and installed by the switchboard builder.
Figure 2-4 One Side of Drawout MDS/MDSX Circuit
Breaker Properly Seated on Extension Rail
Molded Rail
Supports
Extension Rail
Cutout
I.B. 2C12060H08
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