Maintenance
Note: A temporary source of control power and test leads
may be required if the control power source has not been
connected to the circuit breaker. When control power is
connected to the circuit breaker, the closing springs should
automatically charge.
Electrical Close And Trip Check — Control Power Required -
For breakers equipped with electrical close and trip switches
(either Close/Trip switch, or two pushbuttons):
1. Once the breaker springs are charged, move the breaker
Close/Trip switch to the Close position, or press the Close
pushbutton. There should be both the sound of the
breaker closing and indication that the breaker contacts
are closed by the main contact status indicator.
2. As soon as the breaker has closed, the automatic spring
charging process is repeated.
3. After a satisfactory close operation is verified, move the
breaker Close/Trip switch to the Trip position, or press
the Trip pushbutton. Verify by both sound and contact
position that the contacts are open. Completion of these
checks demonstrates satisfactory operation of auxiliary
switches, internal relays and solenoids.
4. For breakers equipped with the external emergency trip
knob (red knob on exterior of breaker), close the breaker
and then use (pull) the emergency trip knob and verify
by both sound and contact position that the contacts are
open.
For breakers not equipped with electrical close and trip
switches, perform the above checks by utilizing the remote
control close and trip signals.
Checks Of Spring Charging Motor - No additional checks
of the spring charging motor are necessary. Once every
10,000 operations, the motor brushes need replacement
(reference kit 18-658-612-886). Use the operation counter
as the basis for establishing the operation frequency.
High Potential Tests
The next series of tests (Vacuum Integrity Test and Insula-
tion Tests) involve use of high voltage test equipment. The
breaker under test should be inside a suitable test barrier
equipped with warning lights.
Vacuum Integrity Check - A high potential test is used to
verify the vacuum integrity of the circuit breaker. This test
is conducted on the circuit breaker with its primary con-
tacts in the Open position.
High Potential Test Voltages - The voltages for high poten-
tial tests are shown in Table 4.
Note: The DC test voltage is given as a reference only. It
represents values believed to be appropriate and approxi-
mately equivalent to the corresponding power frequency
withstand test values specified for each voltage rating. The
presence of this column in no way implies any requirement
for a DC withstand test on AC equipment or that a DC with-
stand test represents an acceptable alternative to AC with-
stand tests. When making DC tests, the voltage should be
raised to the test value in discrete steps and held for a pe-
riod of one minute.
Note: Do not use DC high potential testers
incorporating half-wave rectification. These devices
produce high peak voltages.
These high voltages will produce X-ray radiation.
These devices also show erroneous readings of
leakage current when testing vacuum circuit breakers.
Vacuum interrupters may emit X-radiation.
Can cause serious injury.
X-rays can be produced when a high
voltage is placed across two circuit
elements in a vacuum.
Keep personnel more that six (6) feet away
from a circuit breaker under test. All normal
metallic doors and panels must be installed
during tests.
Table 4. High Potential Test Voltages
High Potential tests employ hazardous
voltages.
Will cause death or serious injury.
Follow safe procedures, exclude unnecessary
personnel and use safety barriers. Keep away
from the breaker during application of test
voltages. After test completion, ground both
ends and the middle ring (if visible) of the
vacuum interrupter to dissipate any static
charges.
Rated
Maximum
Voltage
kV (rms)
Power
Frequency
Withstand
kV (rms)
Field Test Voltage
kV (rms)
kV (dc)
15.5
25.8, 27.6
50
60
37.5
45
53
63.6
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