GE Industrial Solutions PowerVac with ML-18 or ML-18H Mechanism - Manual (Page 9)

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is closed, the charging motor is again energized and the closing
spring is charged as described under “CLOSED SPRING
CHARGING”. Spring charging is possible when the breaker is in
the closed position because the linkage is held in place by the
prop.
5.4—Opening Operation (refer to Figure 17)
By either energizing the trip solenoid or depressing the manual
trip button (item 23, view B), the trip latch (item 19, view D) is
rotated, permitting the linkage to collapse and the vacuum
interrupter contacts to open under the force of the wipe springs
(item 16, view E) and opening springs (item 15, view E). At the
end of the opening stroke, the center phase wipe spring
assembly hits a stop block on the frame that limits overtravel
and rebound. Rotation of the cross shaft from the closed to the
open position operates the auxiliary switch (item 17, view D)
which opens the trip coil circuit. If the closing spring has been
recharged, the linkage will be reset and the trip latch will be in
place on the trip roller, ready for another closing operation.
5.5—Trip-free Operation
The linkage is mechanically trip free in any location on the
closing stroke. Electrically energizing the trip coil while closing
will, after the auxiliary switch contacts change position, rotate
the trip latch and permit the circuit breaker to open fully.
The linkage will reset as in a normal open operation, and the
closing spring will recharge as described under SPRING
CHARGING.
SECTION 6—Electric Control circuit
A typical PowerVac ® circuit breaker ML-18 or ML-18H mechanism
wiring diagram is shown in Figure 16. Check the wiring diagram
supplied with the actual circuit breaker for its wiring.
The close spring-charging motor circuit is established through
the CL/MS (close latch monitor switch) switch if the close latch
is reset and the SM/LS (spring motor limit switch) if the closing
spring is discharged. When the closing spring is charged, the
SM/LS interrupts the circuit.
The IL/MS switch is connected to sense position of negative
interlock. When the breaker is racked between the connect and
disconnect position, the negative interlock roller is depressed as
a result the IL/MS switch is open and does not allow the motor
to charge the closing spring. Once the breaker is rack in the
switch closes allowing the spring charge motor to charge the
closing spring.
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, cam rotation closes the SM/LS contact allowing the
52Y relay to be energized; opening its contacts in the close coil
circuit and sealing itself in through one of its own contacts to
the close signal. This seal-in action prevents re-closing on a
sustained close command as the close signal must be removed
to drop out the Y relay, and reestablish the close circuit, thereby
providing an anti-pump feature.
Circuit breaker mounted auxiliary switch contacts not used in
the control circuit are bought out for control and indication
functions. The metalclad equipment may provide a breaker
operated stationary auxiliary switch for additional contacts
(3, 6 or 10 stages are available.
SECTION 7—Mechanical Checking and Slow Closing
7.1—Visual Inspection
Visually inspect the circuit breaker for any signs of damage or
loose hardware.
7.2—Closing Spring Charging
Manually charge the breaker closing spring using the charging
handle provided (item 1, Figure 4). The closing spring is charged
by a ratcheting mechanism that advances by one ratchet tooth
at a time. When the spring is fully charged and the spring load is
held by the closing latch, the spring indicator (item 3, Figure 1)
will change from “DISCHGD” to “CHARGED”, and a positive snap
will be heard as the spring travels over center.
CAUTION: AFTER THE SPRING IS COMPLETELY CHARGED,
AS INDICATED IN FIGURE 4, FURTHER FORCING CHARGING
HANDLE MAY CAUSE DAMAGE TO THE CLOSING LATCH AND
ITS ASSOCIATED PARTS.
1. Manual charging handle
2. Close spring gag hole
(Shown in closed position)
3. Spring charge indication
1
3
2
Figure 4 Manual charging