I.B. 2C12060H08
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Instruction Book
Page 11
Effective: May 2006
SECTION 3: CIRCUIT BREAKER
DESCRIPTION AND OPERATION
3-1 INTRODUCTION
Magnum DS (MDS), DSX (MDSX) circuit breakers are
available in both drawout and fixed mounting configura-
tions (Figures 3-1 and 3-2). Magnum DSL (MDSL) cir-
cuit breakers with integral current limiters are available
only in a drawout configuration (Figure 3-3). A majority
of features are common to all 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 cir-
cuit breaker. The front escutcheon (faceplate) is com-
mon for all Magnum frame sizes up through 5000
amperes.
Double Wide DS and DSX frame circuit breakers utilize
six (or eight) sets of rear primary connections; these cir-
cuit breakers are available from the factory with several
different phase sequences, distinguishable by the sixth
character in the model number. The phase sequence is
also labeled on the rear of the circuit breaker (Figure
3-4). For these DS and DSX drawout breakers, phase
sequence labels are also supplied with the cassette and
must be applied by the switchgear builder. Circuit brak-
ers with different phase sequences are not interchange-
able. DS and DSX drawout breakers with differing
phase sequence are prevented from insertion into the
cassette by properly assembled rejection key plates
(see section 2-6.2).
The Magnum DSL (MDSL) drawout circuit breaker is
available only in a 3-pole single wide standard configu-
ration. The MDSL is a coordinated combination of a
standard Magnum DS circuit breaker and series con-
nected current limiters. The primary purpose of the cur-
rent limiters is to extend the interrupting rating of the
MDS circuit breaker up to 200,000 amperes.
Figure 3-1 Typical MDS /MDSX Drawout Circuit Breaker Features (Front and Rear Views)
Baffled Arc Chute Cover
Secondary Disconnects (Contacts)
Faceplate (Front Cover)
Drawout Rail Supports
Integral Lifting Handle
5
2
1
6
7
9
4
3
8
10
Primary Disconnect Finger Cluster
Arc Chamber
Primary Vertical Adapter
Sensor Rating Viewing Window
Levering Device Bearing Plate
Padlockable Levering Device Access Door
Circuit Breaker Nameplate
11
12
1
12
3
4
4
5
5
6
6
7
8
9
10
10
11
12
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