ieee/pes switchgear committee meeting (montréal, … dynamic contact resistance measurements on hv...
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Dynamic Contact Resistance Measurementson HV Circuit Breakers
byMichel Landry, IREQ
Fouad Brikci, Zensol Automation Inc.
IEEE/PES Switchgear Committee Meeting(Montréal, October 4, 2005)
Zensol Automation Inc.
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Interrupting chamber of an SF6 circuit breaker
Fixed contacts Moving contacts
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3 Zensol Automation Inc.
Measuring system and sensors for Dynamic Contact Resistance Measurements (DRM)
3 signals to be recordedThe injected current (IDC) of at least 100 AThe voltage drop (VD) across the breaker contactsThe breaker contact travel curve
Features of the acquisition unit3 analog 12-bit resolution inputsSampling frequency ≤ 10 kHzTotal acquisition time = 30-100 sConnection to a portable computer
SensorsHall-effect current sensor (LEM type)Voltage sensorLinear or rotary contact travel sensor
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Measuring parameters
DRM during closing operations is impracticalAbrupt resistance variation from infinity (open contacts) to arcing contact resistance value (≈ 200 µΩ)Undesired noise level due to transient DC current at the moment of arcing contact touch
DRM during opening operationsLow contact speed (≈ 0.002 - 0.2 m/s)Reproducible measurementsEasy to interpretAdequately simulates the actual operating condition of an in-service HV circuit breaker
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Not obvious resistance transition from infinityto arcing contact resistance value (≈ 200 µΩ)
Impractical DRM during closing operations
R (m
Ω)
0
2
4
6
8
0 0.5 1.0 1.5t (ms)
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DRM on a break of a 315-kVcapacitor-bank SF6 circuit breaker
No reproducible measurements
0.5 ms
500 µΩ
Main contact part
At rated speedArcing contact part
t
R (µ
Ω)
Main contact part
Contact speed=0.2 m/s 0.15 m/s
50 ms
100 µΩ
At low speed
Arcing contact part
t
R (µ
Ω)
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DRM on a break of a 120-kVcapacitor-bank SF6 circuit breaker
2 ms
500 µΩ
Presumed main contact part
Arcing contact part
t
R (µ
Ω)
At rated speed5 s
500 µΩ
Main contact part
Arcing contact part
Contact speed= 0.002 m/s
tR
(µΩ)
At low speed
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735-kV 8-break air-blast PK circuit breaker
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Relatively newfixed contact
(F1)
New movingcontact
(M1)
Slightly wornmoving contact
(M2)
Contact sets of PK breakers used fordeveloping new contact wear algorithm
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Seriously damagedmoving contact
(M4)
Worn moving contact
(M3)
Contact sets of PK breakers used fordeveloping new contact wear algorithm
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Laboratory test set-up usinga vertical CNC milling machine
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Contact wear analysis by evaluating the area beneath the dynamic resistance curve
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2
34
4 3
2
1 1:Contact set F1-M12:Contact set F1-M23:Contact set F1-M34:Contact set F1-M4
R (m
Ω)
Ar
(mΩ
.s)
0.5 s1 mΩ
0.5 s
1 mΩ.s
2.7 mΩ.s
5.4 mΩ.s
3.9 mΩ.s
2.8 mΩ.s
t
t
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Rm
Dm
Da
Pa
Time
Ra
Ra * Da
Rm
Da
Pa
Dm
Parameters to be extractedfrom dynamic resistance curve
Arcing contact partArcing contact part
Main contact part
Main contact part
Dynamic resistance curve
Contact travel curve
t0
Contact travel (mm)
R (m
Ω)
R a
nd C
onta
ct tr
avel
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Case Study No. 1315-kV capacitor-bank SF6 circuit breaker
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Case Study No. 1DRM on a 315-kV capacitor-bank SF6 circuit breaker
15 25 355Contact travel (mm)
0
1
3
2
R (m
Ω)
Arcing contact in excellent condition
3.6Ra*Da(mΩ. mm)
34.6Pa(mm)
19.5Da(mm)
15.1Dm(mm)
185Ra(µΩ)
29Rm(µΩ)
2492Operation counter reading
Maincontactpart
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Contact travel (mm)
R (m
Ω)
Case Study No. 2DRM on a 120-kV capacitor-bank SF6 circuit breaker
10.3Ra*Da(mΩ. mm)
45.9Pa(mm)
24.6Da(mm)
21.3Dm(mm)
420Ra(µΩ)
37Rm(µΩ)
687Operation counter reading
0
1
3
2
20 300 10 40 50
Defective arcing contact
Maincontactpart
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1 off-center moving arcing contact tip Damaged fixed arcing contact
Case Study No. 2Damaged moving and fixed arcing contacts
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Case Study No. 2DRM on the same break after contact overhaul
3.4Ra*Da(mΩ. mm)
50.5Pa(mm)
19.7Da(mm)
30.8Dm(mm)
173Ra(µΩ)
33Rm(µΩ)
< 20Operation counter reading
Normal arcing contact
R (m
Ω)
0
1
3
2
25 355 15 45 55
Contact travel (mm)
Maincontactpart
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Case Study No. 3230-kV reactor SF6 circuit breaker
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Case Study No. 3DRM on a 230-kV reactor SF6 circuit breaker
60.3Ra*Da(mΩ. mm)
65.7Pa(mm)
34.2Da(mm)
31.4Dm(mm)
1768Ra(µΩ)
74Rm(µΩ)
204Operation counter reading
Internal restrike
R (m
Ω)
0
1
3
2
20 400 60Contact travel (mm)
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Case Study No. 3Arcing spots on the fixed contacts
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Case Study No. 3DRM on a healthy break of another phase of a
230-kV reactor SF6 circuit breaker
3.1Ra*Da(mΩ. mm)
67.2Pa(mm)
33.5Da(mm)
33.8Dm(mm)
93Ra(µΩ)
34Rm(µΩ)
201Operation counter reading
R (m
Ω)
0
1
3
2
20 400 60Contact travel (mm)
Maincontactpart
Normal arcing contact
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Dynamic Resistance Measurement KitZ-DRM-2
Stable DC current source
Data acquisition system
Voltage and current sensors
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Resdyn software(R as a function of the breaker contact travel)
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Dynamic Resistance Measurement KitZ-DRM-2 (Contact travel sensors)
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Conclusion
New DRM methodOpening operations at low contact speedReproducible curves easy to analyze and interpretVital information about the breaker contact conditionUseful tool for maintenance planning
Six vital diagnostic parametersAverage main contact resistanceAverage arcing contact resistanceMain contact wipeArcing contact wipePosition of the breaker contact at the arcing contact partCumulative area beneath the resistance curve(mΩ.mm)