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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Maintenance
e. Adjustment of Close Latch Shaft
The close latch shaft (Figure 7, l) passes
through the side sheets of the stored
energy mechanism frame at the front of
and below the cam shaft. One end of the
shaft is shaped to make a latch face and
interferes with the close latch arm
(Figure 7, k), which is fixed to the cam shaft.
The other end of the close latch shaft is
attached to a lever positioned by a close
bar adjusting screw (Figure 7, r).
To adjust the close latch shaft perform the
following procedures:
1. Remove the escutcheon.
2. Loosen the locking nut from the close
bar adjusting screw while holding the
position of the close bar adjusting screw
with a screw driver.
3. Back out the close bar adjusting screw
by turning the screw counterclockwise
2 full turns.
4. Manually charge the circuit breaker
main closing spring with a manual
charging handle until the spring charge
indicator displays CLOSING SPRING
CHARGED.
5. Turn the close bar adjusting screw
clockwise until the main closing spring
discharges, then depress the manual
trip operator to OPEN the circuit
breaker.
6. Turn the close bar adjusting screw
3 to 3½ full turns counterclockwise.
Retighten the locking nut holding the
screw.
7. Repeat step 5. Then CLOSE and OPEN
the circuit breaker to ensure proper
operation.
8. Replace the escutcheon.
f. Open and Close Spring Release Lever
Adjustment
If the circuit breaker has rolled over an
obstruction on the floor which caused
displacement of the open or close spring
release lever, adjust the lever if necessary.
The spring release interlock link and the
opening interlock link need to be adjusted
if required.
When the circuit breaker is withdrawn
from the cell to the disconnected position,
the close spring release lever operates
and discharges the main springs in the
mechanism.
6) Electrical
Operation
After performing any necessary mechanical
and lubrication maintenance, operate the
circuit breaker electrically several times to
ensure that the electrical control system
works properly. See
Ch 4 Installation,
D. P
LACING
THE
C
IRCUIT
B
REAKER
I
NTO
S
ERVICE
,
5) Electrical Operation Check.
C.
V
ACUUM
I
NTERRUPTER
AND
C
ONTACT
A
REA
1) Vacuum Interrupter and Contact Erosion
At each inspection the vacuum interrupters
should be checked for contact erosion.
The circuit breaker must be closed for this
check. Each new vacuum interrupter is
set with a gap of about 0.150” to 0.188”
between the pivot block and the lock
nut on the operating pushrod stud. As
the contacts erode with use, this gap will
decrease. The factory setting of the lock
nut gap varies for each vacuum interrupter.
