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58
Recommended Renewal Parts and Replacement Procedures
PowlVac
®
STD Vacuum Circuit Breaker
IB-60201
f. Repeat the above steps as required to
obtain the specified stroke.
i. With the circuit breaker closed,
measure the gap between the
contact loading spring yoke and the
nut on the operating pushrod stud.
Record this value in the space of
the label on the vacuum interrupter
marked “New”. Deduct 0.188” from
this dimension and record the result
in the space marked “End of life”.
ii. Replace the interphase barrier
assembly and front cover of the
circuit breaker.
Refer to
Ch 4 Installation
,
d. p
lAcInG
the
c
IrcuIt
B
reAker
I
nto
S
ervIce
,
2) Vacuum
Integrity
to perform the vacuum integrity
test once replacement vacuum interrupter
is installed.
2) Sliding Contact Finger Assembly
To clean, inspect, and lubricate the sliding
contact finger assemblies (Figure 33, c),
remove the four sockethead screws holding
the sliding contact finger assemblies and
pivot the assemblies down. Wipe the
lubrication from the surfaces of the lower
contact block, sliding contact fingers, and
the lower primary disconnecting devices
and examine the surfaces. The sliding
contact finger locations should present a
burnished silver contact without copper
appearance at more than one location.
If the copper is visible at more than one
location per pole or the silver is torn on
the lower contact block, the vacuum
interrupter assembly should be replaced.
The sliding contact finger assemblies on
the PowlVac® circuit breakers are reversible.
Since only the upper ends of the fingers
experience any wiping action, the wear is
normally confined to that end. If the upper
ends of the fingers show noticeable wear,
the finger assemblies can be reversed.
Loosen the bolt holding the rear mounting
clip and remove the finger assembly.
Invert the assembly and replace it in the
mounting clips. Tighten the bolt holding
the rear mounting clip. If copper is visible
at more than one contact location on a
finger assembly, that assembly should be
replaced. Apply a light coat of Mobilgrease
28 contact lubricant to both sides of the
contact blocks and to the contact areas of
the lower primary disconnecting devices,
then reassemble the sliding contact
finger assemblies by replacing the four
sockethead screws and tighten to a torque
value of 8-12 lb-ft.
3) Closing Coil Assembly
This assembly is located center and below
the circuit breaker mechanism
(Figure 2, ab).
CAUTION
CAUTION
!
Ensure that the control circuits are
deenergized and the circuit breaker is
deenergized, disconnected by means of a
visible break, and securely grounded. Do NOT
start to work on a closed circuit breaker or a
circuit breaker with the main closing spring
charged.
Perform the following steps to replace the
closing coil assembly:
a. Remove the front cover of the circuit
breaker.
b. Elevate the circuit breaker so that there
is at least 6 inches of clear space below
the base pan of the breaker.
c. Disconnect the closing coil assembly
from the wire harness.
