Advertisement
5.0
1.0
1.0
Ground disconnect
2.0
Racking mechanism release handle
3.0
Trip-free interlock
Figure 28: Circuit breaker interlocks and ground disconnect
Mechanism-operated cell (MOC) switch
(optional)
Figure 26: MOC switch operating arm on a
circuit breaker and Figure 27: MOC (bottom)
and TOC (top) switches and associated
terminal blocks show the principal
components that provide optional control
flexibility when operating the circuit breaker
in the TEST (optional) and CONNECT
(standard) positions.
Figure 26: MOC switch operating arm on a
circuit breaker shows the MOC-switch
operating arm that projects from the right
side of the circuit breaker, above the bottom
rail structure. The MOC-switch operating arm
is part of the jack-shaft assembly and directly
reflects the OPEN or CLOSED position of the
circuit breaker primary contacts.
As the circuit breaker is racked into the
appropriate position inside the switchgear,
the MOC-switch operating arm engages the
pantograph linkage (refer to Figure 29: Circuit
breaker compartment (up to 50 kA shown) on
page 30). Operation of the circuit breaker
causes the pantograph linkage to transfer
motion to the MOC switches located above
the pantograph. The "a" and "b" contacts can
be used in relaying and control-logic
schemes.
All circuit breakers contain the MOC-switch
operating arm. However, MOC switches are
provided in the switchgear only when specified.
2.0
3.0
6.0
4.0
4.0
Closed circuit breaker racking interlock
5.0
Circuit breaker frame
6.0
Rating interlock
Figure 27: MOC (bottom) and TOC (top) switches
and associated terminal blocks
The circuit breaker engages the MOC switch
only in the CONNECT (operating) position
unless an optional TEST position pickup is
specified in the contract. If a TEST position
pickup is included, the circuit breaker will
engage the auxiliary switch in both positions.
Up to 24-stages may be provided.
Truck-operated cell (TOC) switch
Figure 27: MOC (bottom) and TOC (top)
switches and associated terminal blocks
shows the optional TOC switch. This switch is
operated by the circuit breaker as it is racked
into the CONNECT position.
Various combinations of "a" and "b" contacts
may be optionally specified. These switches
provide control and logic indication that a
circuit breaker in the cell has achieved the
CONNECT (ready-to-operate) position.
Figure 26: MOC switch operating
arm on a circuit breaker
29
Advertisement
