1. PRESENTATION ON
HV & EHV CIRCUIT BREAKER
MAINTENANCE
BY :
MR. Manish Pandya
Director
Manish Engicorp Pvt. Ltd.
2. EQUIPMENTS OF SUB-
STATIONS
POWER TRANSFORMER
CIRCUIT BREAKERS.
CURRENT TRANSFORMER AND POTENTIAL
TRANSFORMER
ISOLATORS
LIGHTNING ARRESTORS
BUS BAR
EARTHINGS
CABELS
PROTECTIVE RELAYS
BATTERY AND BATTERY CHARGERS
PLCC EQUIPMENTS
3. VACUUM CIRCUIT
BREAKERS
A Vacuum circuit breaker is a
circuit breaker in which vacuum
is used to extinct the arc. VCB
have excellent interruption and
dielectric recovery
characteristics, and can
interrupt the high frequency
currents which result from arc
instability, superimposed on the
line frequency current.
4. VCBs are capable of interrupting currents with a very
high (di/dt), typically in the range of 150 - 1000A/μs and
consequently the high- frequency current may be
interrupted during one of the high frequency excursions
through zero. This is known as virtual current chopping.
5. WHAT IS AN ARC?
An electric arc is a visible plasma
discharge between two electrodes
that is caused by electrical current
by ionizing gasses or air.
Electric arcs occur in nature in the
form of lightning.
7. CONSTRUCTION OF VACUUM
BOTTLE
The main parts of a typical Vacuum Bottle are
■ Fixed contact
■ Moving contact
■ Bellows
mounted inside a vacuum chamber.
9. GENERAL ARRANGEMENT
ALL CIRCUIT BREAKERS HAVE MINIMUM
FIVE ARRANGEMENTS
• ARC QUENCHING AND ISOLATION
• MECHANICAL ENERGY CHARGING
(STORE ENERGY)
• CLOSING MECHANISM
• CLOSE DEMPING MECHANISM
• TRIPPING MECHANISM
• TRIP DAMPING MECHANISM
10. WHY MAINTENANCE REQUIRED?
1) FOR TROUBLE FREE WORKING
2) FOR LONG LIFE
3) FOR AVOIDING UN-PLANNED SHUTDOWN
4) TO MINIMIZE SERVICE DOWN TIME
5) TO GET BETTER UTILIZATION OF CAPITAL
INVESTMENT
6) TO REDUCE COST OF FAILURE AND
DAMAGE TO SUBSEQUENT COMPONENT
7) TO IMPROVE SAFETY BY REDUCING
ACCIDENT AND GET BETTER QUALITY
CONDITION
11. PLANNING OF MAINTENANCE
1) TEST, MEASURE AND ANALISE THE SERVICE DATA
(COLLECTION OF PERIODIC DATA).
2) PREPARE FOR SHUTDOWN TO EVALUATE CURRENT
CONDITION. (PLANNING)
3) COLLECT ALL CURRENT PARAMETER AND DATA BY
ALL AVAILABLE METHODS AND IF PROBLEM IS MINOR
MAKE ADJUSTMENT FOR SMOOTH OPERATION.
(PREVENTIVE MAINTENANCE)
4) EVALUATE THE PROBLEM FROM COLLECTED DATA AND
FIND OUT MOST SUITABLE SOLUTION. (PERIODIC DATA
ANALYSIS)
5) MAKE A PROCEDURE TO ELEMINATE PROBLEM FROM A
SYSTEM. (REPAIR, MAINTENANCE OR OVERHAULING)
12. TESTING OF BREAKERS
1) INSULATION RESISTANCE VALUE TEST
2) DC CONTACT RESISTANCE MEASUREMENT
3) BREAKER OPERATING TIME MEASUREMENT
4) CONTACT TRAVEL AND WIPE MEASUREMENT
5) MEASUREMENT OF RESISTANCE OF CLOSING AND
TRIPPING COIL
6) DC / AC HIGH VOLTAGE TEST OF VCB AS
RECOMMENDED BY MANUFACTURER.
17. GENERAL PROBLEMS OF VACUUM
CIRCUIT BREAKER
1) TRACKING DUE TO DUST
2) DAMAGE DUE TO POOR MECHANICAL DAMPING.
3) DAMAGE OF ARCING AND MAIN CONTACT
4) WRONG SETTING OF MECHANISM ASSLY. AND
POLE ASSLY.
5) DETERIORATION OF INSULATIOIN MATERIAL DUE
TO AGING.
6) VERMIN AND PROOFING PROBLEM
