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Operation and maintenance of
IZM low voltage air circuit breakers
MOELLER www.moeller.net/de/support
10/09 AWB1230-1605
Effective October 2009
Section 3: Circuit breaker description
and operation
Introduction
IZM circuit breakers are available in physical frame sizes and in both
drawout and fixed mounting configurations (Figure 14 and Figure
15). 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 frame sizes that cover all
continuous current ratings through 6300A.
IZM99 and IZM63 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. The
phase sequence is also labeled on the rear of the circuit breaker
(Figure 16). For drawout breakers, phase sequence labels are also
supplied with the cassette and must be applied by the switchgear
builder. Circuit breakers 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 “Rejection interlocks” on page
11).
Figure 14. 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
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