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IZM63 / IN63 low voltage air circuit breaker
MN013014EN May 2021 www.eaton.com.cn
Section 3: Circuit breaker description and operation
3-2 Basic circuit breaker assembly
IZM63 circuit breakers use a rigid frame housing construc-
tion of engineered thermoset composite resins. This con-
struction provides high-strength structural properties, excel-
lent dielectric characteristics, and resistance to arc tracking.
The three-piece construction approach provides support
while isolating and insulating power conductors.
A two-piece engineered thermoset composite resin case
encloses current paths and arc chambers. The chambers act
to channel arc gases up and out of the circuit breaker during
interruption.
The operating mechanism sits on the front of the case and is
electrically isolated and insulated from current contact struc-
tures. It is covered by an insulating front cover.
3-3 Operating mechanism
The IZM63 / IN63 operating mechanism is based on the
proven cam and spring design. It is easily accessed by
removing few cover screws and the front cover (Figure
3-6). The mechanism is a two-step stored energy mecha-
nism. Potential energy is stored to close the circuit breaker.
Sufficient energy to open the circuit breaker remains avail-
able after a closing operation.
Figure 3-5 Typical construction (right side view)
Figure 3-6 Electrically operated drawout circuit breaker with front cover removed
1
2
(Case)
(Front cover)
7
2
1
4
3
5
6
8
2
1
3
5
6
7
8
4
Secondary wiring points
Field installable accessories
(3 maximum)
Trip unit
Electric charging motor
Manual charge handle
Operations counter (optional)
Padlockable levering device
access door
Breaker position indicator
