5-15. VOLTAGE REGULATOR VR101 REPLACEMENT.
Voltage regulator VR101 (3, Figure 5-9) is located inside
the top section of Cabinet B.
See Figure 5-9.
Loosen two hexagon head screws and swing open cover.
Tag and disconnect all electrical wiring.
Remove hexagon head screws (1) and lockwashers (2) and lift out voltage regulator VR101 (3).
See Figure 5-9.
Position voltage regulator VR101 (3) in the top section of cabinet B and secure with hexagon head
screws (1) and lockwashers (2).
Make all wiring connections as tagged. Ensure ground strap is securely fastened.
Close cover and secure with two hexagon head screws.
5-16. VOLTAGE REGULATOR VR101 REPAIR.
Repair of voltage regulator VR101 is limited to replacement of
those components identified in Figure 5-10. The unit must be returned to the manufacturer for additional repair or
Tag leads prior to disconnecting them. Note polarity and orientation of components when tagging.
Exercise care not to apply excessive heat when unsoldering components. Use heat sinks whenever
unsoldering solid-state components.
Position replacement components in accordance with tags and Figure 5-10.
Solder components into place. Check solder joints after they have cooled to ensure proper
Double-check wire tags and then discard them.
LOAD CIRCUIT BREAKER CB101
5-17. GENERAL. Interruption in the load circuit breaker CB1 01 is performed by the vacuum interrupter module
assemblies (Figure 5-13) which are mounted vertically within the breaker frame. The vacuum interrupter module
assemblies consist of a pair of butt contacts, one moveable and one fixed, which are hermetically sealed in a high
vacuum. The vacuum interrupter module assemblies require only a short contact gap for circuit interruption. The
resulting high operating speed allows the entire operating sequence, from fault to clear, to be consistently performed in
three cycles or less. The possibility of restriking is minimized because the dielectric strength of the vacuum gap recovers
more rapidly than the rate of rise of the applied voltage. The primary connections to the switchgear are made through six
primary disconnects (Figure 5-13) mounted horizontally at the rear of the breaker. The operating mechanism contains all
necessary controls and interlocks. It is mounted at the front of the breaker so that it can be easily accessed for
inspection and servicing. Opening and closing can be performed electrically or manually. A schematic diagram of the
control circuitry is presented in Figure 5-14.
The following subparagraphs describe the operation of the various components of the control circuitry.
The auxiliary switch (Figure 5-15) is a multi-stage switch used to operate those circuits
which are dependent upon either the position of the breaker contacts or the position of the drive springs. The schematic
diagram (Figure 5-14) indicates how each of the auxiliary switch stages are interconnected with breaker circuitry.
The function of each stage is discussed below:
The a-type auxiliary contacts are connected in series with trip solenoid TC (Figure 5-16). Since these
stages are open when the breaker is in the open position, the auxiliary contacts prevent the trip
solenoid from being energized when the breaker is in the open position.
The b-contact, connected in series with the closing solenoid (Figure 5-16), disables the closing
solenoid when the breaker contacts are in the closed position.