TM 96115604-34
NAVFAC P-8-633-34
5-18. LOAD CIRCUIT BREAKER CB101 INSPECTION. Ensure that the generator set is shut down and fully
deenergized, load cables are in the park position and surge protectors are grounded. Remove load circuit breaker
CB101 in accordance with paragraph 2-17. Inspect entire load circuit breaker and operating mechanism for loose
hardware and worn or broken parts. All wiring should be checked for loose connections and damaged insulation. Inspect
all bearings and contact surfaces for damage or excessive wear. Check the adjustments in accordance with paragraph
5-21.
NOTE
It is important to measure and record the spring overtravel of a vacuum interrupter when it is
first put into service to ensure reliable service.
To ensure reliable interruption, perform a contact erosion inspection. Any contact erosion will result in a reduction in
spring overtravel. Contact erosion can be determined by dosing the breaker and measuring the spring overtravel. The
difference between this measurement and the original spring overtravel measurement at the time the vacuum interrupter
was put into service represents contact erosion. When the spring overtravel has been reduced to 0.30 inch (7.62 mm),
the primary contacts have eroded 1/8 inch (3.2 mm) and the vacuum interrupter must be replaced. Refer to paragraph 5-
22, step b, for the procedure to determine spring overtravel.
WARNING
All personnel must stay at least 6 feet (18 mm) away from vacuum Interrupters under test to
avoid Injury In case of explosion.
WARNING
Discharge to ground the primary disconnects and vacuum Interrupter mid-band rings before
handling to prevent Injury to personnel as a result of electrocution.
WARNING
I To avoid injury to personnel, always remove the load circuit breaker CB1O1 from Its cubide
and discharge or block the return and drive springs.
5-19. LOAD CIRCUIT BREAKER CB1O1 TEST.
Remove load circuit breaker CB101 in accordance with
paragraph 2-17. Perform a hipot test on each vacuum interrupter while the breaker is in the OPEN position. Gradually
raise the voltage to 19 kV. The contact gap of the vacuum interrupter should sustain this potential for 1 minute. If any
vacuum interrupter fails, it must be replaced. Observe the following instructions when performing the hipot test
a.
Do not exceed the voltage specified above.
b.
Do not test vacuum interrupters with open gaps less than 112 inch (1.3 mm).
c.
Discharge to ground the primary disconnects (Figure 5-13) and vacuum interrupter mid-band ring (Figure 5-
13) before handling. These areas can retain a static charge after a hipot test.
WARNING
To avoid Injury to personnel, always remove the load circuit breaker from Its cubide and
discharge or block the return and drive springs.
WARNING
Discharge to ground the primary disconnects and vacuum Interrupter mid-band rings before
handling to prevent Injury to personnel as a result of electrocution.
5-43
