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O & M Of CIRCUIT BREAKER
K N Srinivasan
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Breaker Chamber
Drive Mechanism
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Air,oil,SF6
Breaker
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Driving Mechanism
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Contact timing test Testy
Travel & velocity Test
Contact resistance Test
AC Insulation Test
Oil Dielectric Test
Oil gas analysis Test
Water content Test
SF6 by-products Test
Sf6 mixture percentage Test
Auxiliary circuit
insulation Test
First trip Test
Dynamic resistance contact Test
Vibration Test Test
X Ray Test
Ultrasound(731) Test
Capacitance Test
Air pressure consumption Test
Infrared temperature Test
Tightness Test
Tests
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Age
Cond
itionalprobabilityoffailu
re
Infant mortality Useful life period Phase out period
Classical Maintenance Thinking
Design,
Reliability andmanufacturing
Preventive and Condition based
maintenance
RLA
Bath Tub Curve
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ROUTINE TESTS
S. No.Routine tests
1 Dielectric test on main circuit
2 Dielectric test on auxiliary & control
circuit3 Design identification test
4 Mechanical operating test
5 Measurement of resistance of main circuit
THE ROUTINE TESTS ARE TO BE COSIDERED AS ACCEPTANCE TESTS
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TYPE TESTSIEC: 62271-100]
1 Dielectric tests
2 Radio Interference voltage test
3 Resistance of the main circuit
4 Temp. rise test
5 Short-time withstand current & peak withstandcurrent
6 Mechanical operation test at ambient temp.
7 Short-circuit current making/ breaking tests
8 Capacitive current charging tests:-Line charging current breaking tests
-Cable charging current breaking tests
Switching impulse voltage ( applicable for 420 kV CB and above)
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Types of Faults
Random Time Induced
Non-observable Non-observableobservable
Maintenance Strategies for combating the Above Fault Types
Accept breakdowns Readiness to repair
Improve reliability Design out maintenance
Condition Monitoring Continuous monitoring
Periodic monitoring
Periodic overhauls Periodic replacements
Reconditioning
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Swedish Standard SS-EN 13306, 2001
MAINTENANCE TERMINOLOGIES
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BREAKDOWN MAINTENANCE
Equipment Productivity High downtime
Frequent failures
Poor quality
Reduced safety
Employee Productivity High work time
High waiting time Low morale
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PREVENTIVE MAINTENANCE
Planned Maintenance based on periodicityAdvantages
Reduction in failures
Enables planning
Disadvantages Over maintenance
Human intervention in equipment technology
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PREDICTIVE MAINTENANCE
Maintenance based on machine conditionAdvantages
Better availability
Reduced maintenance costs Safety and quality
Operation and maintenance planning
Design Improvements
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CONDITION MONITORINGCONDITION MONITORING
OBJECTIVE (30%)SUBJECTIVE(70%)
SIMPLE AIDS INSTRUMENTAL
TECHNIQUES
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Symmetry &Asymmetry
Steady Operation -no asymmetry
SwitchOn V peak - No asymmetry
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Fault MVA = 3 x VL x IL
VL= Line voltage
IL = Line current
Contact
separation
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400kV CB
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420 kV SF6 With Pneumatic Mechanism
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INTERRUPTER DESIGN
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Internal Details of Interrupter
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Contact Configuration
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PIR ASSEMBLY FAILURES MECHANICAL
BREAKAGE OF PTFEROD
BLASTING OF CB DUE
TO PIR PROBLEM
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OVERHAULING OF CBs
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TypesTypes
RatingsRatings
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Total Break Time (As Per IEC: 62271-100
72.5 kV
145 kV
245 kV
420 kV
800 kV
60 ms to 100 ms
60 ms to 100 ms
Not exceeding 60 ms
Not exceeding 40 ms
Not exceeding 40 ms
Pre Insertion Resistor420 kV 300-450 Ohms
800 kV 300-40 0 Ohms
Types of CB Mechanisms
Spring operatingPneumatic
Hydraulic
All store potential energy in elastic medium and facilitate fast release
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36 8
12.5
16
25
40
630
630
630
1250
1250
1250
1250
1600
1600
1600
2500
2500
72.5 12.5
16
20
31.5
800
800
1250
1250
1250 1600
1600
2000
2000
123 12.5
20
25
40
800 1250
1250
1250
1600
1600
1600
2000
2000
2000
145 12.5
20
25
31.5
40
800 1250
1250
1250
1250
1600
1600
1600
1600
2000
2000
2000
2000 3150
Rated
Voltage
(kV)
Rated ShortCircuit
Breaking current
(kA)
Rated normal current (Amp)
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245 20
31.5
40
1250
1250 1600
1600
2000
2000 3150
420 31.5
40
5063
1600
1600
2000
2000
2000
3150
31503150
40004000
800 40 2000 3150
Rated
Voltag
e(kV)
Rated Short Circuit
Breaking current
(kA) Rated normal current (Amp)
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Reasons of CB Failures
MECHANICAL - 74%(OPERATING COMPONENTS FAILURES)
ELECTRICAL - 16%(DIELECTRIC FAILURE)
DRIVEs etc. - 10%
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DYNAMIC CONTACT RESISTANCE MEASUREMENT (DCRM)
CONTACT RESISTANCE MEASUREMENT DURING CLOSINGAND TRIPPING OPERATION. C-O DELAY TIME ABOUT 300MS.
100 AMP CURRENT IS INJECTED THROUGH CB CONTACTS.
VOLTAGE DROP AND CURRENT IS MEASURED TO COMPUTE
CONTACT RESISTANCE.
VARIATION IN FINGER PRINT OF DCRM INDICATE PROBLEMIN ARCING AND MAIN CONTACTS.
Static contact resistance measurement
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Basic connection arrangement for DCRMMeasurement
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DCRM CONNECTION ARRANGEMENT
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Typical DCRM Signature
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DCRM can detect
Erosion of Arcing Contact
Erosion of main contact
Contact misalignments
Contact wipe of main and arcing contact Main & arcing contact resistance
Healthiness of damping system
Contact travel & speed
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SF6is easily recycled for reuseStandards establishedgas handling equipment is readily available
ContaminationGas handlingLeakageDesorption from surfacesDecomposition by electrical dischargesSecondary reactions
Mechanical generation of dust particles
EffectsHealth riskCorrosion
Insulation performance of gas gapsInsulation performance of insulator surfacesSwitching capabilityHeat transfer
SF6 gas quality testing purity & dew point . recycling.
Ai d CF4 (fl b )
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Air and CF4 (fluorocarbon )handling and switching arcs
dilution with new SF6gas
SF4, WF6(Tungsten hexafluoride ), SOF4, SOF2, SO2, HF, SO2F2
From arcing, partial discharges, and secondary reactions
absorbants used in gas handling equipment
Solid Decomposition Products: CuF2, WO3, WO2F2, WOF4, AlF3
contact erosion and internal arcing
dust filters of 1 micrometer pore
Carbon and Metal Dust/Particlespolymer carbonization and mechanical wear
1 micrometer pore size filters in gas handling equipment
OilFrom pumps and lubrication
IEC 480 is being revised to provide an international standard for purity levels
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Minimize leakage rate
Gas monitoring
Reclaim
Quality ChecksAir and CF4:speed of sound or thermal conductivityHumidity:electronic hygrometers or dew point instruments
Decomposition Products:chemical reaction tubes with visual indication
Final Disposal
Use a thermal process followed by a calcium hydroxide scrubber to form solid
sulphates and fluorides:CaSO4CaF2
These are naturally minerals used in construction and toothpaste
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CONDITION ASSESSMENT TECHNIQUES
1. ON LINE CONDITION MONITORING
TECHNIQUES
2. OFF LINE CONDITION ASSESSMENT
TECHNIQUES
ON LINE CONDITION MONITORING
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TECHNIQUES
1. SF6 GAS PRESSURE MONITORING
2. TRIP COIL SUPERVISON3. AUXILIARY CONTACTS OPERATING
TIMINGS
4. CONTACT SPEED MEASUREMENT BYINSTALLING TRANSDUCERS
5. LINE CURRENT AND CUMULATIVE FAULTCURRENT USING EXTERNAL CT- UNDER
EVALUATION
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OFF LINE CONDITION ASSESSMENT TECHNIQUES
1. OPERATING TIMINGS OF MAIN AND AUXILIARYCONTACTS-1 Y
2. TRIP/CLOSE COIL CURRENTS MEASUREMENT-1Y
3. STATIC CONTACT RESISTANCE MEASUREMENT-2Y
4. VIBRATION MEASUREMENT UNDER EVALUATION
STAGE5. CONTACT TRAVEL MEASUREMENT-3Y
6. DEW POINT MEASUREMENT OF SF6 GAS-2Y
7. DYNAMIC CONTACT RESISTANCE MEASUREMENT-3Y
8. TAN DELTA MEASUREMENT OF GRADINGCAPACITORS- 3Y
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Breaker Operation Checks(From CBIP Manual )
1 CB Operating timings (Main,PIR,Aux) Y
2 Static contact resistance measurements 2Y
3 DCRM 2Y
4 Checking of Pole discrepancy relay Y
5 Functional checks, Duty cycle operation including SF6 density monitor Y
6 Checking of all operational lock-outs including SF6 density monitor Y
7 Checking of all interlocks Y
8 Checking of pressure settings Y
9 Cleaning of breaker interrupter, support insulrs,PIRs & grading Cs
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A
Accptable Norms
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