12
Figure 6: Vacuum circuit breaker magnetic-actuator operator module
Item
Description
48.6
Angled lever
49.0
Contact pressure spring
63.1
Lever - phase C
63.3
Lever - phase A
63.5
Lever - phase B
48.6
49.0
49.0
49.0
63.3
63.5
63.1
The vacuum interrupter movable contact is
connected to the flexible shunt (29.1)
associated with the other pole head and to
the driving mechanism of the circuit breaker.
The metal bellows provide a secure seal
around the movable contact, preventing loss
of vacuum while permitting motion of the
movable contact along the axis of the
vacuum interrupter.
When the two contacts separate, an arc is
initiated that continues conduction up to the
following current zero. At current zero, the
arc extinguishes and any conductive metal
vapor that has been created by and supported
the arc condenses on the contacts and on the
surrounding arc shield. Contact materials and
configuration are optimized to achieve arc
motion and to minimize switching
disturbances.
Primary connections
Figure 4: Vacuum circuit breaker magnetic-
actuator operator module on page 11
illustrates the pad provision to accept the
primary connections.
Each circuit breaker has three connection
pads at the fixed end of the vacuum
interrupter, and three connection pads on the
flexible connectors that are associated with
the movable contact of the vacuum
interrupter. Interconnecting bus in the circuit
breaker enclosure connects these connection
pads to the roof bushing terminals. Bolting
hardware is M12 x 1.75 grade 8. Torque M12
bolts to 52 ft-lb (70 Nm).
Phase barriers (if applicable)
For certain ratings, insulating barriers are
attached to the circuit breaker and provide
suitable electrical insulation between the
vacuum interrupter and primary conductors
and the enclosure.
NOTICE
Capacitor discharge plug (105.2)
Disconnect control power prior to removing or
replacing the capacitor discharge plug. Refer to
Figure 2 on page 7.
To discharge capacitors:
Disconnect control power to the circuit breaker
by opening the disconnect device (device 08 in
the typical schematic in Figure 14 on page 24)
located in the control compartment.
After control power is off, disconnect the
capacitor discharge plug (105.2) from the
controller board (105.0) to discharge capacitors.
To reconnect capacitors:
Disconnect control power to the circuit breaker
by opening the disconnect (device 08 in the
typical schematic in Figure 14 on page 24)
located in the control compartment.
Insert the capacitor discharge plug (105.2) (with
six pins) into the left-hand receptacle on the
controller board (105.0). Ensure that the plug is
properly seated and the plug position is level
with the power supply connection plug (105.5)
that is located to the right of the capacitor
discharge plug.
After the capacitor discharge plug is firmly
seated, reconnect control power to the circuit
breaker (device 08 in the typical schematic in
Figure 14 on page 24).
