Instruction Book
Effective: November 2017 Page 55
IB131016EN For more information visit: www.Eaton.com
6-6 INSULATION
In VCP-T and VCP-TR circuit breakers, insulation
maintenance primarily consists of keeping all insulating
surfaces clean. This can be done by wiping off all
insulating surfaces with a dry lint free cloth or dry paper
towel. In case there is any tightly adhering dirt that will
not come off by wiping, it can be removed with a mild
solvent or distilled water. Be sure that the surfaces are
dry before placing the breaker in service. If a solvent
is required to cut dirt, use Stoddard's Solvent (Eaton
55812CA) or commercial equivalent. Secondary control
wiring requires inspection for tightness of all
connections and damage to insulation.
6-7 INSULATION INTEGRITY CHECK
Primary Circuit: The integrity of primary insulation may
be checked by the AC high potential test. The test
voltage depends upon the maximum rated voltage of
the breaker. For the breakers rated 5.0kV, 12kV and
15.0 kV, the test voltages are 15kV, 21 kV and 27 kV
rms respectively. Conduct the test as follows:
Close the breaker. Connect the high potential lead of
the test machine to one of the poles of the breaker.
Connect the remaining poles and breaker frame to
ground. Start the machine with output potential at zero
and increase to the test voltage. Maintain the test
voltage for one minute. Repeat for the remaining
poles. Successful withstand indicates satisfactory
insulation strength of the primary circuit.
If a DC high potential machine is used, make certain
that the peak voltage does not exceed the peak of the
corresponding AC RMS test voltage.
Secondary Circuit: Isolate the motor by pulling apart
the two insulated quick disconnecting terminals in the
two motor leads provided for this purpose. Connect all
points of the secondary disconnect pins 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 voltage to 1500 volts
rms. Maintain the voltage for one minute. Successful
withstand indicates satisfactory insulation strength of
the secondary control circuit. Remove the shooting
wire and reconnect the motor leads.
6-8 PRIMARY CIRCUIT RESISTANCE CHECK
Since the main contacts are inside the vacuum
chamber, they remain clean and require no
maintenance at any time. 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 side of the disconnect for each pole. The
resistance should not exceed the values shown in
Table 6.3.
6-9 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
manually and electrically. Check the closing and
opening times to verify that they are in accordance with
the limits in paragraph 5-4.1.
6-10 LUBRICATION
Maintenance of these circuit breakers and cassettes
consists mainly of keeping them clean with a minimal
amount of lubrication recommended. VCP-T and
VCP-TR circuit breakers should be lubricated every 3
years or 2000 operations with a high quality 10W30
motor oil and/or magna-lube G teflon grease C-H
#53701AI as indicated in Figure 6-5. As required for
smooth operation, lubricate the drawout cassette also
with a high quality 10W30 motor oil and/or magna-
lube G teflon grease C-H #53701AI as indicated in
Figure 6-6.
Table 6.3 Typical Resistance Measurements
Rated Continuous
Current (amperes)
Resistance
(µohms)
600
800
1200
1600
2000
2500
46
44
39
36
25
24
6-11 TROUBLESHOOTING
Refer to Table 6.4 for troubleshooting suggestions. It
will help to determine the probable causes of simple
circuit breaker problems and possible corrective
actions. If the problem cannot be resolved with the aid
of this guide, contact the Eaton service center for
more in-depth assistance.
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