Operating Mechanism; Manual Operation; Figure 27 . Typical Electrically Operated Drawout Circuit - Eaton SBN-508 Instructions For Installation, Operation And Maintenance

Instructional Leaflet
Effective March 2012

Operating Mechanism

The Magnum SB operating mechanism is based on the proven
cam and spring design of the DSII power circuit breaker . It is
easily accessed by removing four cover screws and the front
cover (Figure 27) . The mechanism is a two-step stored energy
mechanism . Potential energy is stored to close the circuit
breaker . Sufficient energy to open the circuit breaker remains
available after a closing operation .

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 behind the charging handle and pull
out . This permits a gloved hand to grasp the handle and begin
charging (Figure 28) . It takes from 5 to 7 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
1 . Secondary Wiring Points
2 . Field Installable Accessories (3 maximum)
3 . Trip Unit
4 . Electric Charging Motor
5 . Manual Charge Handle
6 . Operations Counter (optional)
7 . Padlockable Levering Device Access Door
8 . Breaker Position Indicator
Figure 27. Typical Electrically Operated Drawout Circuit Breaker with Front Cover Removed
22 EATON CORPORATION www.eaton.com
IB2C12063H03
Instructions for Installation, Operation and
Maintenance of Magnum SB Insulated Case
Low Voltage Power Circuit Breakers
(Figure 20) . 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 are 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 . All of these UL
listed optional devices can be installed easily in the field . For
more details on these devices, refer to "Accessory Devices" on
page 48 of this manual .
An electrical operator which is used to charge the closing
spring automatically can be added to a manually operated
circuit breaker in the field (Figure 29) . Manually operated circuit
breakers are pre-wired to accept this addition .