Page 342 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

19 Check that the tripping rod and the armatures of the tripping releases, move freely without blocking or friction.
20 Circuit breaker regular maintenance record sheet model given in Table 2.

Note: If the releases are found to be under friction clean the relevant part thoroughly.

Table 2
Maintenance record sheet for circuit breaker

Particulars Signature of
Complained Attended Description
Sl.No. Date Particulars of the engineer
by by of fault
replacement in-charge
1

2

3

4

5

1 Run-time maintenance

(a) Ensure the load current is within the normal range.
(b) Ensure the relevant indicators conform to the normal circuit indicators.

(c) Look out for any abnormal sound, like chatter, humming, or buzzing during operation and as noise is an
indication of poor contact or under-voltage.

(d) Ensure no discolouration at the contact points and the coil is not burned out.
(e) Keep the contactor clean, both inside and outside. Refrain from having a poor operating state in the
surrounding environment, which includes keeping away from the moisture, dust, oil, physical obstruction
that affects the full closure of the contactor and limit the degree of vibration.

2 Inactive maintenance
(a) Ensure the cable is secure, the wire insulation is not damaged, and refrain from having any loose ends. If
the contact is loose, look out for any traces of burns.

(b) Ensure strict measurement of the interphase insulation resistance of AC contactors, and the resistance
value is not less than 10M.

(c) Clean the contactors regularly.
(d) For the maintenance of the contact system, Ensure the reliability of the contact, the endurance of the coil,
and the function of the middle spring. Check if the contactor coil is open weld, burnt, and/or discoloured.
(e) For the maintenance of the iron core Ensure the iron core is removed when conducting power failure
inspection. General inspection includes,
(i) Look out for any abnormal sound.

(ii) Check if the short circuit ring is damaged and replace any damaged rings timely if necessary

325

CITS : Power - Electrician & Wireman - Exercise 116