I.B. 2C12060H08
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Instruction Book
Effective: May 2006
Page 10
Figure 2-12 Typical Fixed Magnum DS Circuit Breaker
The circuit breaker mechanism is interlocked such
that charged closing springs are automatically dis-
charged if the circuit breaker is levered into or out
of the cell. Discharge takes place between the DIS-
CONNECT and TEST position.
2-7 FIXED CIRCUIT BREAKER
Magnum DS fixed type circuit breakers differ from the
drawout version in that it has no levering device, primary
disconnects and secondary disconnects (Figure
2-12
).
In addition, a fixed circuit breaker does not have a stan-
dard feature to hold the breaker in a trip-free position.
To ensure the proper sequence of operation between
two or more circuit breakers, an optional key interlock is
mounted through the front panel (Figure
3-44
).
FAILURE TO COMPLY WITH INSTALLATION OF
THE FIXED MOUNTED MDSX ARC HOOD ASSEM-
BLY COULD RESULT IN EQUIPMENT DAMAGE,
BODILY INJURY OR EVEN DEATH.
The MDSX fixed mounted breaker is shipped with an
included arc hood assembly. This assembly is
required
to be installed
on the top of the breaker prior to the unit
being placed in service.
Circuit breaker terminals have holes for making bolted
horizontal primary bus connections. Adapters are avail
Mounting
Foot
Figure 2-11 Levering Position Indication
CONNECT
TEST
DISCONNECT
CONNECT
TEST
DISCONNECT
NOTICE
able for making vertical primary bus connections.
Secondary connections can be made through standard
terminal blocks or a special connector compatible with
the drawout circuit breaker’s type secondary connector.
Both secondary connection devices are mounted at the
top front of the circuit breaker.
The fixed circuit breaker frame has two mounting feet,
one on each side, to permit the fixed circuit breaker to
be securely mounted. Each mounting foot has two slot-
ted mounting holes which are used to bolt the circuit
breaker securely in place. Use either M10 or 3/8” bolts
for this purpose. Refer to the dimensional drawings
referred to in Section 5 (Fixed Circuit Breakers) for cir-
cuit breaker and bus stab dimensions.
Refer to the circuit breaker weights in Table 2.1 to
ensure that the panel on which a fixed circuit break-
er is to be mounted is capable of supporting the
weight.
2-8 CIRCUIT BREAKER OPERATION
Circuit breakers should be operated manually and/or
electrically before they are put into service. This can be
done during the installation process or some later date
prior to start-up. To check circuit breaker operation, fol-
low the operational procedures outlined in Section 3 for
both manually operated and electrically operated circuit
breakers.
NOTICE
!
WARNING
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