Magnum
16
1812.900A
3 CIRCUIT BREAKER DESCRIPTION
AND OPERATION
3.1 Introduction
Magnum circuit breakers are available in three physical
frame sizes and in both drawout and fixed mounting
configurations (Figure 2-5 and Figure 3-2). A majority of
features are common to both configurations, and will be
discussed in this section. The mounting features unique
to the drawout and fixed configurations will be covered
individually in Sections 4 and 5 respectively.
Controls and indicators for both drawout and fixed circuit
breakers are functionally grouped on the front of the
circuit breaker. The front escutcheon (faceplate) is
common for the three frame sizes that cover all
continuous current ratings through 6300 amperes.
Double Wide frame circuit breakers utilize six (or eight)
sets of rear primary connections; these circuit breakers
are available from the factory with several different phase
sequences, distinguishable by the sixth character in the
model number (Figure 1-3). The phase sequence is also
labeled on the rear of the circuit breaker (Figure1-3).
For drawout breakers, phase sequence labels are also
supplied with the cassette and must be applied by the
switchgear builder. Circuit brakers with different phase
sequences are not interchangeable. Drawout breakers
with differing phase sequence are prevented from
insertion into the cassette by properly assembled
rejection key plates (see section 2.6.1).
Figure 3-1: Typical Drawout Circuit Breaker Features (Front and Rear Views)
1. Baffled Arc Chute Cover
2. Secondary Disconnects (Contacts)
3. Faceplate (Front Cover)
4. Drawout Rail Supports
5. Integral
Lifting
Handle
6. Primary Disconnect Finger Cluster
7. Arc
Chamber
8. Tripper
Bar
9. Sensor Rating Viewing Window
10. Levering Device Bearing Plate
11. Padlockable Levering Device Access Door
12. Circuit Breaker Nameplate
1 5 8 4
10
12 11 3
2 7
6
9
