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New generation IZM97, 99 low voltage air circuit breaker instruction manual
MN013010EN February 2020 www.eaton.com.cn
Section 3: Circuit breaker description and operation
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Primary disconnect finger cluster
Arc chamber
Tripper bar
Sensor rating viewing window
Levering device bearing plate
Padlockable levering device access door
Circuit breaker nameplate
Baffled arc chute cover
Secondary disconnects (contacts)
Faceplate (front cover)
Drawout rail supports
Integral lifting handle
Figure 3-1 Typical drawout circuit breaker features (front and rear views)
Section 3: Circuit breaker description and
operation
3-1 Introduction
IZM9 circuit breakers are available in two physical frame
sizes and in both drawout and fixed mounting configura-
tions (Figure 3-1 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 the 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 6300A.
Double-wide frame circuit breakers use six (or eight) sets of
rear primary connections; these circuit breakers are available
from the factory with several different phase sequences.
The phase sequence is also labeled on the rear of the circuit
breaker (Figure 3-3). For drawout breakers, phase sequence
labels are also supplied with the cassette and must be
applied by the switchgear builder. Circuit breakers with dif-
ferent 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).
