Maintaining The Main Contacts And Replacing The Contact System - Siemens SENTRON 3WA1 Manual

Inspection and maintenance
5.7 Maintaining the main contacts
The number of mechanical operating cycles is usually greater than the number of
purely electrical operating cycles; they can be equal at most.
For information on the maximum mechanical service life, see Chapter Technical
specifications of 3WA circuit breakers (Page 489).
5.7.2

Maintaining the main contacts and replacing the contact system

A check for contact erosion is performed during maintenance of the main contacts:
1. Perform all the steps outlined in Chapter Preparing for maintenance work (Page 400).
2. Charge the stored energy mechanism manually.
3. If an undervoltage release is installed, take off the operator panel and remove the
undervoltage release. Removal is performed in the reverse sequence.
4. Close the circuit breaker.
5. Remove the arc chute, see Chapter Maintaining the arc chutes (Page 403).
6. Check whether the indicator pin is still visible.
Note
Use a mirror or a smartphone camera to perform the visual inspection on fixed-
mounted circuit breakers.
(1) Indicator pin
(2) Indicator pin visible
(3) Indicator pin no longer visible
406
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06