ieee/pes switchgear committee meeting (montréal, … dynamic contact resistance measurements on hv...

1

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.

2 Zensol Automation Inc.

Interrupting chamber of an SF6 circuit breaker

Fixed contacts Moving contacts

2


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


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

3


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)


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)

4


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


735-kV 8-break air-blast PK circuit breaker

5


Relatively newfixed contact

(F1)

New movingcontact

(M1)

Slightly wornmoving contact

(M2)

Contact sets of PK breakers used fordeveloping new contact wear algorithm


Seriously damagedmoving contact

(M4)

Worn moving contact

(M3)

Contact sets of PK breakers used fordeveloping new contact wear algorithm

6


Laboratory test set-up usinga vertical CNC milling machine


Contact wear analysis by evaluating the area beneath the dynamic resistance curve

1

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

7


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


Case Study No. 1315-kV capacitor-bank SF6 circuit breaker

8


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


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)


0

1

3

2

20 300 10 40 50

Defective arcing contact

Maincontactpart

9


1 off-center moving arcing contact tip Damaged fixed arcing contact

Case Study No. 2Damaged moving and fixed arcing contacts


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

10


Case Study No. 3230-kV reactor SF6 circuit breaker


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)


Internal restrike

R (m

Ω)

0

1

3

2


11


Case Study No. 3Arcing spots on the fixed contacts


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)


R (m

Ω)

0

1

3

2


Maincontactpart

Normal arcing contact

12


Dynamic Resistance Measurement KitZ-DRM-2

Stable DC current source

Data acquisition system

Voltage and current sensors


Resdyn software(R as a function of the breaker contact travel)

13


Dynamic Resistance Measurement KitZ-DRM-2 (Contact travel sensors)


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)

ieee/pes switchgear committee meeting (montréal, … dynamic contact resistance measurements on hv...

Documents