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50
Maintenance
PowlVac
®
STD Vacuum Circuit Breaker
IB-60201
6. Depress the manual close operator
and rotate the crank arm until
resistance is felt.
7. Depress and hold the manual trip
operator inward and rotate the
crank arms until the spring charge
indicator displays, CLOSING SPRING
DISCHARGED.
8. Reinstall the circuit breaker main
closing spring.
e.
Adjustment of Close Latch Shaft
The close latch shaft (Figure 2, aa)
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 2, y), 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 2, ae).
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.
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,
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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 1/4” to 5/8” between
the contact loading spring yoke and the
lock nut on the operating pushrod stud. As
the contacts erode with use, this gap will
decrease. Because the factory setting of
the lock nut gap varies for each vacuum
interrupter, a label is provided on the
lower part of each vacuum interrupter.
The original factory setting of the gap and
the end-of-life measurement of this gap
is recorded on the label. When the gap
measurement reaches the end-of-life value
given on this label, the vacuum interrupter
should be replaced.
