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Automatic spring-charging check
Refer to the specific wiring information and
rating label for your circuit breaker to
determine the voltage required and where
the control-voltage signal should be applied.
Usually, spring-charging power is connected
to secondary-disconnect fingers SD16 and
SD15, closing control power to SD13 and
SD15 and tripping power to SD1 and SD2.
Note: Secondary-disconnect terminals are
numbered 1-16, from top to bottom.
When control power is connected to the type
GMSG vacuum circuit breaker, the closing
springs should automatically charge, if the
racking crank is not engaged.
Note: A temporary source of control power
and test leads may be required if the control
power source has not been connected to
the switchgear.
The automatic spring-charging features of the
circuit breaker must be checked. Control
power is required for automatic spring-
charging to take place.
1. Open control-power circuit by opening
the control-power disconnect device.
2. Install the circuit breaker end of the split-
plug jumper (if furnished) to the circuit
breaker as shown in Figure 5: Split-plug
jumper connected to circuit breaker. The
split-plug jumper is secured over the
circuit breaker secondary contacts with
knurled thumb screws.
3. Install the switchgear end of the split-plug
jumper to the secondary-disconnect block
inside the switchgear cubicle as shown in
Figure 6: Split-plug jumper connected to
switchgear. The jumper slides into place
and interconnects all control power and
signal leads (for example, electrical trip
and close contacts) between the
switchgear and the circuit breaker.
4. Energize (close) the control-power circuit
disconnect.
5. Use the close and trip controls (refer to
Figure 1: Type GMSG vacuum circuit
breaker front panel controls on page 8)
to first close and then open the circuit
breaker contacts. Verify the contact
positions visually by observing the OPEN/
CLOSED indicator on the circuit breaker.
6. De-energize control power by repeating
Step 1. Disconnect the split-plug jumper
from the switchgear before disconnecting
the circuit breaker end.
7. Perform the spring discharge check again.
Verify the closing springs are DISCHARGED
and the primary contacts of the type
GMSG vacuum circuit breaker are OPEN.
Final mechanical inspections without
control power
1. Make a final mechanical inspection of the
circuit breaker. Verify the contacts are in
the OPEN position, and the closing springs
are DISCHARGED.
2. Check the upper- and lower-primary studs
and contact fingers shown in Figure 7:
Circuit breaker primary disconnect. Verify
mechanical condition of finger springs
and the disconnect studs, check for loose
hardware, damaged or missing primary-
disconnect contact fingers and damaged
disconnect studs.
3. Coat movable primary-contact fingers
(refer to Figure 7: Circuit breaker primary
disconnects) and the secondary-
disconnect contacts (refer to Figure 23:
Secondary disconnect on the circuit
breaker on page 28) with a light film of
Siemens contact lubricant number
15-172-791-233.
4. The type GMSG vacuum circuit breaker is
ready for installation into its assigned
cubicle of the metal-clad switchgear. Refer
to removal procedures and install the
circuit breaker into the switchgear.
5. Refer to the switchgear instruction
manual for functional tests of an installed
circuit breaker.
Figure 5: Split-plug jumper
connected to circuit breaker
Figure 6: Split-plug jumper
connected to switchgear
Figure 7: Circuit breaker
primary disconnects
13
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