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IZM32 / IN32 low voltage air circuit breaker
MN013017EN May 2022 www.eaton.com
Section 3: Circuit breaker description and operation
3-3.1 Manual operation
On manually operated circuit breakers, the closing spring
can only be charged manually. To manually charge the
spring, insert one finger in the recess of the charging
handle and pull out. This permits a gloved hand to grasp
the handle and begin charging. It takes from five to seven
downward strokes on the charging handle to complete the
manual charging process. It is possible to manually recharge
the spring immediately after closing the circuit breaker
and before it has been tripped open. Standard manually
operated circuit breakers are closed and opened by hand
using the Manual ON and Manual OFF buttons respectively
located on the front of the circuit breaker (Figure 3-4).
Performing either operation is accomplished by pressing
and releasing the appropriate button. Access to these
pushbuttons can be limited by the use of an optional,
padlockable cover. In addition, complete access to the ON
button can be prevented with an optional prevent close
cover. The status of the springs and the primary contacts
is always indicated in an indicator window just above the
pushbuttons.
Electrically operated optional devices are available to
automatically close or trip a manually operated circuit
breaker. An electrical spring release is available to close a
manually operated circuit breaker. Two optional devices,
a shunt trip, and an undervoltage release, are available
to automatically trip (open) a manually operated circuit
breaker. These optional devices can be installed easily in
the field. For more details on these devices, refer to the
corresponding instructions leaflet.
An electrical motor operator that is used to charge the
closing spring automatically can be added to a manually
operated circuit breaker in the field (Figure 3-8). Manually
operated circuit breakers are pre-wired to accept this
addition.
3-3.2 Electrical operation
For electrically operated circuit breakers, the springs are
normally charged through the use of an electrical motor
operator (Figure 3-8). The springs can, however, be charged
manually as just described in the previous paragraph
(Figure 3-7).
Like the manually operated circuit breaker in the previous
paragraph, electrically operated circuit breakers can also be
manually closed and opened through the use of the front-
mounted Manual ON and Manual OFF buttons.
An electrically operated circuit breaker from the factory
is also equipped as standard with a spring release to
close the circuit breaker electrically. An optional shunt
trip and undervoltage release are also available to trip
(open) an electrically operated circuit breaker. Refer to the
corresponding instructions leaflet for more details on both
standard and optional devices.
3-3.3 Anti-pump feature
The circuit breaker has both mechanical and electrical
antipump features. If the circuit breaker is closed on a
fault condition (and trips open while the CLOSE signal is
maintained), using either the mechanical pushbutton or
the electrical close coil, it will not make another attempt to
close until the close command is removed and reapplied.
For electrical closing, a Latch Check Switch (LCS) option is
available (check the corresponding instructions leaflet for
more details) that will block the application of the electrical
close command until the breaker is ready to close.
Figure 3-7 Electrical motor operator to charge closing
spring
Figure 3-8 Charging motor can be installed in the field
(installed)
Motor operator
installed