22
PowerVac
®
5kV Vertical Lift
Chapter 6. Control Circuit
6-1 Controls
A Standard internal wire harness for a PowerVac
®
VL circuit breaker ML-19 mechanism is shown
in Figure 19. The wiring from the breaker
internals to the secondary disconnect varies
with each breaker. Two typical breaker wiring
diagrams have been provided (Figure 20 and Fig-
ure 21). Always follow the wiring diagram sup-
plied with the actual circuit breaker for trouble
shooting purposes.
The close spring-charging motor circuit is es-
tablished through the CL/MS (Close Latch Moni-
tor Switch) Switch, if the close latch is reset
and the SM/LS (Spring Motor Limit Switch)
Switch is closed, the motor will charge the clos-
ing spring. When the closing spring is charged,
the SM/LS interrupts the circuit.
The close coil circuit is established through two
normally closed 52Y relay contacts, and the Latch
Checking Switch (LCS). If the trip latch is reset,
an auxiliary switch contact 52b is also in series
with the close coil and closes when the breaker
is open and opens when the breaker is closed.
During a close operation, the cam rotation closes
the SM/LS contact allowing the 52Y relay to be
energized. The 52Y relay opens its contacts, in
the close coil circuit and seals itself in through
one of its own contacts. This seal-in action pre-
vents re-closing on a sustained close command.
The close signal must be removed to drop out
the 52Y relay and reestablish the closing cir-
cuit. This provides the anti-pump feature.
Circuit breaker-mounted auxiliary switch con-
tacts that are not used in the control circuit are
brought out for control and indication functions.
The metal-clad equipment may provide a breaker-
operated stationary auxiliary switch for addi-
tional contacts.
Figure 19. Typical ML-19 mechanism internal wiring connections.
