Siemens 3AH3 Instruction Manual page 38

38
Checks of the spring-charging motor
(88.0)
No additional checks of the spring-charging
motor are necessary. If it is necessary to
remove or replace the spring-charging
motor, torque motor-mounting hardware to
7.3-8 ft-lb (10-11 Nm).
Anti-pump relay
If it is necessary to remove the connections
to the anti-pump relay, use care to avoid
damaging the relay. Replace the relay if the
relay terminals are damaged or loose in the
relay body.
Vacuum interrupters
The life expectancy of vacuum interrupters
is a function of the numbers of interruptions
and magnitude of current interrupted (refer
to Table 3 and Figure 21).
The vacuum interrupters must be replaced
before the number of mechanical operations
(listed in Table 2) are reached, or when the
contacts have been eroded beyond allowed
limits. Vacuum interrupter replacement
procedures are detailed in the following
maintenance instructions.
The vacuum interrupter contact life curves
(refer to Figure 21) are offered as a guide to
expected life.
Vacuum-integrity check (using
mechanical test) (refer to Figure 22)
Before putting the circuit breaker into
service, or if a vacuum interrupter is
suspected of leaking as a result of
mechanical damage, check the vacuum
integrity either mechanically as described in
this section, or alternatively, electrically
using a high-potential test set as described
in the next section.
Open and isolate the circuit breaker and
detach the insulating coupler (48.0) from
lever (48.6) (refer to Figure 22).
The atmospheric pressure will force the
moving contact of a hermetically sealed
vacuum interrupter into the "Closed"
position, causing lever (48.6) to move into
the position shown in Figure 21.
A vacuum interrupter may be assumed to be
intact if it shows the following
characteristics:
1. An appreciable closing force has to be
overcome when lever (48.6) is moved to
the "Open" position by hand (refer to
Figure 22);
2. When the lever is released, it must
automatically return to the "Closed"
position with an audible sound as the
contacts touch.
After checking the vacuum, reconnect the
lever (48.6) to the insulating coupler (48.0)
(refer to Figure 22).
High-potential tests employ hazardous voltages.
Will cause death and serious injury.
Follow safe procedures, exclude unnecessary personnel and use safety
barriers. Keep away from the circuit breaker during application of test
voltages. Disconnect the split plug jumper from between the circuit breaker
and switchgear before conducting high-potential tests.