I.B. 8295A61H03
Page 39
Effective 7/97
Secondary Circuit:
Isolate the motor by disconnecting two motor leads pro-
vided for this purpose. Connect all points of the sec-
ondary terminal block with a shooting wire. Connect this
wire to the high potential lead of the test machine. Ground
the breaker frame. Starting with zero, increase the volt-
age to 1500 volts rms. Maintain the voltage for one
minute. Successful withstand indicates satisfactory insu-
lation strength of the secondary control circuit. Remove
the shooting wire and reconnect the motor leads.
7-8 PRIMARY CIRCUIT RESISTANCE CHECK
Since the main contacts are inside the vacuum cham-
ber, they remain clean and require no maintenance at
any time. Unlike most typical circuit breaker designs,
VCP-WR breakers do not have sliding contacts at the
moving stem either. Instead they use a highly reliable
and unique flexible clamp design that eliminated the
need for lubrication and inspection for wear.
If desired, the DC resistance of the primary circuit may
be measured as follows: close the breaker, pass at least
100 amps DC current through the breaker. With the low
resistance instrument, measure resistance across the
studs on the breaker for each pole. The resistance
should not exceed the values shown in Table 7.2.
7-9 MECHANISM CHECK
Make a careful visual inspection of the mechanism for
any loose parts such as bolts, nuts, pins and rings.
Check for excessive wear or damage to the breaker
components. Operate the breaker several times manu-
ally and electrically. Check the closing and opening
times to verify that they are in accordance with the limits
in Table 5.1.
7-10 LUBRICATION
All parts that require lubrication have been lubricated
during the assembly with molybdenum disulphide
grease. Cutler-Hammer M No. 53701QB. Over a period
of time, this lubricant may be pushed out of the way or
degrade. Proper lubrication at regular intervals is
essential for maintaining the reliable performance of the
mechanism. Once a year or every 2000 operations
whichever comes first, the breaker should be relubricat-
ed. The locations shown in Figure 7-1 should be lubri-
cated with a drop of light machine oil.
After lubrication, operate the breaker several times man-
ually and electrically.
Roller bearings are used on the pole shaft, the cam
shaft, the main link and the motor eccentric. These
bearings are packed at the factory with a top grade slow
oxidizing grease which normally should be effective for
many years. They should not be disturbed unless there
is definite evidence of sluggishness, dirt or parts are dis-
mantled for some reason.
If it becomes necessary to disassemble the mechanism,
the bearings and related parts should be thoroughly
cleaned. Remove old grease in a good grease solvent. Do
not use carbon tetrachloride. They should then be washed
in light machine oil until the cleaner is removed. After the
oil has been drawn off, the bearings should be packed
with Cutler-Hammer Grease 53701QB or equivalent.
Figure 7-4 Typical “T” Contact Wipe Indicator
Rated Continuous
Current (amperes)
600
800
1200
1600
2000
Resistance
(microohms)
46
39
39
26
26
Table 7.2 Typical Resistance Measurements
Summary of Contents for 150 VCP-WR 1500
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