Service and maintenance
7.2 Tests during inspections and after tripping
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
212
Manual, 10/2018, L1V30499596002-01
7.2
Tests during inspections and after tripping
The following tests must be conducted during inspection, after tripping, and after lengthy
storage under certain environmental conditions before re-commissioning. These can be
performed with a TD310 test device to power the ETU. They are not absolutely necessary
after delivery from the factory because the devices are 100 % tested before shipment. A trip
test confirms correct mechanical functioning of the tripping plunger on the trip coil, actuated
by the ETU. Electronic monitoring of the entire connection between the current transformers,
ETU, and trip coil is performed continuously by the electronics itself (watchdog).
Items to be tested
Checks
Enable alarms
Connect the ETU to a test device and check that no alarms are
present.
Status of the circuit
breaker
On the ETUs of the 3-series, the status of the circuit breaker must not
be incorrect (see tables of the LED display in Chapter Alarms
(Page 203)). Perform a close/open operation on the circuit breaker
and check that no alarms have occurred.
On the ETUs of the 6-series, the status of the circuit breaker must be
correctly shown on the display. Perform a close/open operation on the
circuit breaker and check that the change in circuit breaker status is
correctly displayed.
Trip test
Make a trip attempt with the circuit breaker closed during an idle peri-
od (without circulating currents of the mains connection) and check
that the circuit breaker opens.
7.3
Maintenance intervals
Environment with standard conditions
Following initial commissioning, the equipment/system must be serviced at least once per
year or after 2000 switching operations.
Note
These maintenance intervals also apply to circuit breakers that are used irregularly or that
remain in the same switch position for long periods.
Dusty environment
If the circuit breaker is operated in a dusty environment (dust component > 1 mg/m
3
), it
should be maintained at least twice a year or after 1000 switching operations.