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Instruction Book
Page 18
Effective: May 2006
Figure 3-12 Circuit Breaker Closing Springs Being
Manually Charged
3-4.2 ELECTRICAL OPERATION
For electrically operated circuit breakers, the springs are
normally charged through the use of an electrical operator
(Figure 3-13). The springs can, however, be charged
manually as just described in the previous paragraph
(Figure 3-12).
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 paragraph
3-8 for more details on both standard and optional
devices.
3-4.3 ANTI-PUMP FEATURE
The Magnum circuit breaker has both mechanical and
electrical anti-pump features. If the circuit breaker is
closed on a fault condition (and trips open while the
CLOSE signal is maintained), using either the mechani-
cal pushbutton or the spring release, it will not make
subsequent attempt to close until the close command is
removed and reapplied. Note that if the close signal is
applied prematurely (before the breaker is completely
charged and latched), the close command will be
ignored until it is removed and reapplied. For electrical
Figure 3-13 Electrical Motor Operator to Charge
Closing Spring
closing, a Latch Check Switch (LCS) option is available
(see paragraph 3-8.1) which will block the application of
the electrical close command until the breaker is ready
to close.
3-5 ARC CHAMBERS
The Magnum DS/DSX/DSL circuit breakers utilizes arc
chambers to insulate and isolate individual poles from
one another, from the rest of the circuit breaker, and
from operating personnel (Figure 3-1). Arc chambers
are molded and integral parts of the circuit breaker
frame. Enclosed within each arc chamber is an arc
chute which mounts over each set of primary contacts.
After the main contacts part, any remaining current is
driven to the arcing contacts (Figure 3-14). Magnetic
action draws the arc to the arc chute. As the arcing
contacts separate, the moving arcing contacts discharge
into the arc chute plates while the integral arc runner
also helps to draw the arc into the arc chute (Figure
3-15).
3-5.1 ARC CHUTE
The Magnum DS/DSX/DSL arc chutes mount down over
the arcing contact. V-shaped arc chute plates attract
the arc and interrupt it. The top arc plate, which is a
part of the arc chute itself, also helps to attract the arc
away from the moving arcing contact and up into the arc
chute's V-shaped plates (Figure 3-16 and 3-16a).
For more information visit: www.EatonElectrical.com
Electrical Motor
Operator
I.B. 2C12060H08
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