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Instructions for VR-Series
Replacement Breakers for
Westinghouse Type B20B/B22B
IB01301018E
I.B. 94A1994R01
Page 28
Effective: April 2005
FAILURE TO REPLACE A VACUUM INTERRUPTER ASSEMBLY
WHEN CONTACT EROSION MARK IS NOT VISIBLE OR WIPE IS
UNSATISFACTORY, WILL CAUSE THE BREAKER TO FAIL TO
INTERRUPT AND THEREBY CAUSE PROPERTY DAMAGE OR
PERSONNEL INJURY.
6.6 INSULATION
In VR-Series 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. But 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 Cutler-
Hammer 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 4.76 kV, 8.25 kV and
15 kV the test voltages are 15 kV, 27 kV and 27 kV RMS, 60 Hz
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.
Open 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 disconnect-
ing 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 1125 RMS, 60 Hz. 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.
Figure 6-2 Vacuum Interrupter Showing Contact Erosion
Indicator With Breaker Open (Shown here for clarity
purposes only)
Figure 6-3 Vacuum Interrupter Showing Contact Erosion
Indicator With Breaker Closed (Indicators are
checked only when breaker is closed.)
WARNING
