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Trip-free functionality
Refer to Figure 15: Stored-energy operating
mechanism on page 20.
Trip-free functionality is accomplished by
blocking movement of the close latch pawl
(62.5.2) when the manual trip pushbutton
(54.0) or associated locking provisions for
preventing closing are in use (e.g., trip-free
padlock provisions).
Opening
If the circuit breaker is to be tripped locally,
the tripping spring (64.0) is released by
pressing the trip button (54.0). In the case of
an electrical command being given, the
shunt-trip coil 52T (54.1) unlatches the
tripping (opening) spring (64.0). The tripping
spring turns the jack shaft (63.0) via lever
(63.5); the sequence being similar to that for
closing.
Rapid auto-reclosing
Since the closing spring is automatically
recharged by the motor-operating mechanism
when the circuit breaker has closed, the
operating mechanism is capable of an "Open-
Close-Open" duty cycle as required for rapid
auto-reclosing.
The type GMSG circuit breaker is suitable for
use in applications with a rated reclosing-time
interval of 0.3 seconds, per ANSI/IEEE C37.06-
2009.
While the type GMSG-GCB generator circuit
breaker is capable of rapid reclosing duty, fast
reclosing should never be used in a generator
circuit to avoid major damage to the
generator.
Manual operation
Electrically-operated vacuum circuit breakers
can be operated manually if the control
supply should fail.
Manually charging the closing spring
Refer to Figure 16: Use of manual-spring
operation crank on page 22.
Insert the hand crank (50.0) in hole (50.1)
and turn it clockwise (about 48 revolutions)
until the indicator (55.0) shows CHARGED.
The hand crank is coupled with the charging
mechanism via an over-running coupling;
thus the operator is not exposed to any risk
should the control supply be restored during
charging.
Manual closing
To close the circuit breaker, press the close
button (53.0). The OPEN/CLOSED indicator
(58.0) will then display CLOSED and the
closing-spring condition indicator (55.0) will
now read DISCHARGED.
Manual opening
The tripping spring is charged during closing.
To open the circuit breaker, press the trip
button (54.0) and OPEN will be displayed by
indicator (55).
Note: For arc-resistant type GM-SG-AR
switchgear, the circuit breaker can be opened
manually when the circuit breaker
compartment is closed (refer to "Racking
crank engagement procedure" on page 11).
Indirect releases (dual-trip or
undervoltage) (optional)
The indirect release provides for the
conversion of modest-control signals into
powerful mechanical-energy impulses. It is
primarily used to trip medium-voltage circuit
breakers while functioning as a secondary
(dual-trip) release or undervoltage-release
device.
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