This document discusses maintenance and installation of circuit breakers. It outlines two types of maintenance: corrective maintenance which is done after failure, and preventive maintenance which is done on a schedule to prevent failures. Preventive maintenance is recommended for switchgear. The document then details 13 steps for circuit breaker maintenance including inspection, cleaning, drying, checking contacts and mechanisms. It concludes with 13 steps for circuit breaker installation including foundation preparation, assembly, testing, and energization.

1. MAINTENANCE AND INSTALLATION
OF
CIRCUIT BREAKER
By,
Rohini Haridas
Assistant Professor,
Dept of Electrical Engineering,
SSGM College of Engineering,Shegaon

2. Lack of maintenance may results in failure in
operation
Maintenance
Breakdown or
corrective
maintenance
Preventive
maintenance

3. Breakdown or corrective maintenance
activities are undertaken after failure of an
equipment
Such a maintenance results in outage of circuitSuch a maintenance results in outage of circuit
breaker and supply
In general, it consist of locating the trouble ,
repair and recommissioning

4. Preventive maintenance
is undertaken to ensure smooth and efficient
working of a system, equipment.
This type of maintenance is undertaken as per
schedule before breakdown of a system or
equipment
Repair or replacements are made to ensure that no
breakdown occurs at any time during the service

5. For switchgear and protective equipment,
preventive maintenance is recommendedpreventive maintenance is recommended
because failure of a switchgear can not be
permitted

6. General Maintenance
Activities
Inspection Servicing Examination Overhaul

7. Steps in maintenance of CB
1. General Inspection
o Observe the Circuit Breaker visually .
o Note the cleanliness, terminals, earth connections,
reading of counters, level of quenching medium
and pressure of quenching medium

8. 2. Cleaning and drying
o Use clean cloths which does not leave fibers or
particles on the surface
o Use air pressure jet for cleaningo Use air pressure jet for cleaning
o Other cleansing agents recommended by
manufacturer

9. 3. Insulation surface
o Inspect visually, carefully for the signs of cracks
or any other defects
o Clean the internal surfaces and external insulating
surfacessurfaces
o Insulation should be free from electrical or
mechanical defects
o Perform insulation resistance test, it gives
indication about the health of insulation

10. 4. Drying
Circuit breaker pole can be internally dried by
circulating dry hot air.circulating dry hot air.

11. 5. Interrupter
o Observation, cleaning, replacement of main/arching
contacts .
o Cleaning of other parts as well
o Removal of carbon decomposed product
o Cleaning terminals and sliding contact surface
o Cleaning of venting systems to ensure free passage of
oil/gas

12. 6. Mechanism
• Check operation open and close
• Checking simultaneous opening and closing of
three poles
• Check operation counter
• If the mechanism has operated more than 1000
times, it needs very close operation and may need
overhaul

13. 7. Main connections
Ensure that good contact is maintained
and connections are right and secure

14. 8. Earth connections
9. Auxiliary devices
10. Isolating contacts
11. Overload devices and protective relays11. Overload devices and protective relays
12. CT and PT
13.Final verification

15. INSTALLATION
1) Check the readiness of foundations and their
dimensions as per the drawing
2) Check the level of foundation surface2) Check the level of foundation surface
3) Place the base frame of circuit breaker in position
4) Assemble operating mechanism in its position

16. 5) Give auxiliary supply
6)Tighten all bolts and other hardware
7) If provision available, operate slow opening and
closing
8) Measure insulation resistance
9)Fill quenching medium after drying
10) Check leakage and ensure leakage free assembly

17. 11) Check its opening and closing operation
12) Measure timing and check simultaneous
operation of three polesoperation of three poles
13) Operate the CB by operating relevant relays