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Knowledge Is PowerSM

Apparatus Maintenance and Power Managementfor Energy Delivery

Power Factor Testing - Circuit Breakers

Gary HeustonDoble Engineering Company

August 22, 2004 Doble Training2

Circuit Breakers


Circuit Breakers


• Terminology

• Circuit breaker tests

• Power factor test

- applicable policies

- procedures

- analysis of results

- diagnostic tests

- case studies

▪ case 1: effect of connected bus

▪ case 2: SF6 breaker in satisfactory condition

▪ case 3: damaged contact assembly

Agenda


▪ case 4: deteriorated grading capacitor dead tank SF6 breaker

▪ case 5: deteriorated bushing in vacuum breaker

▪ case 6: oil breaker not completely closed

▪ case 7: deteriorated air-magnetic breaker

▪ case 8: deteriorated grading capacitor

▪ case 9: contaminated SF6 gas in live tank breaker

Agenda


• Dead tank switching device

Switching device in which a vessel(s) at ground potentialsurrounds and contains interrupter(s) and insulating medium.

• Live tank switching device

Switching device in which the vessel(s) housing theinterrupter(s) is at a potential above ground.

Source: IEEE Dictionary

Terminology


Terminology


1 2

Terminology


42 61 3 5

Terminology


Terminology

1 3 5

2 4 6


Circuit Breaker Tests

Routinely includes these measurements:

• Power factor

- bushings

- circuit breaker

- insulating mineral oil

• Analysis of mechanical operation

• Contact resistance

sensitive to quality of contacts and connections

• Operational

• Infra-red

sensitive to hot-spots


Circuit Breaker Tests

It may also include these measurements:

• Insulation resistance

sensitive to contamination and deterioration

• Insulating fluid

- mineral oil

▪ physical, chemical and electrical properties

▪ dissolved gases and metals

- SF6 gas

▪ moisture, purity, acidity and arc by-products


Power Factor Test

Because of different vessel types and arrangements, differentoperating principles and internal construction, and differentinterrupting methods and mediums, circuit breakers are perhapsthe most complicated apparatus to test. Any procedure shouldstress all insulating components, to include:

• Entrance bushings

• Interrupter assemblies

• Insulated operating rods

• Any grading capacitors

Any procedure should also provide some assistance in locating anycontamination and deterioration.


Applicable Test Policies

It is necessary to address specific aspects of this testing, toinclude:

• Averaging effect

- isolate from system

- perform searching series of tests to maximize sensitivity oftest to localized problems

• High external surface losses

- clean bushings

- perform Hot-Collar test

• High levels of electrostatic interference

in general, breakers are low capacitance specimens


Averaging Effect

Perform searching series of tests to maximize sensitivity of test tolocalized conditions.


Dead Tank SF6 Circuit Breakers


Power Factor Test

Dead Tank SF6 Circuit Breaker Procedure 1

• Bushings

- Hot-Collar

• Breaker

- 6 open-breaker tests

- 3 open-breaker USTs

Applies to all single-contact SF6 breakers.

Inherently low losses require bus disconnected.

All tests with breaker open.


Power Factor Test

Nothing connected to remaining bushings.

Test Breaker HV LV Leads Test ModePosition Cable Red Blue

1 Open 1 - - GST Ground Red Blue2 Open 2 - - GST Ground Red Blue3 Open 3 - - GST Ground Red Blue4 Open 4 - - GST Ground Red Blue5 Open 5 - - GST Ground Red Blue6 Open 6 - - GST Ground Red Blue7 Open 1 2 - UST Measure Red Blue8 Open 3 4 - UST Measure Red Blue9 Open 5 6 - UST Measure Red Blue

Dead Tank SF6 Breaker, Procedure 1


Power Factor Test

Primarily stresses• Left-side bushing• Operating rod• Any left-side support

insulation• SF6 gas

Open-Breaker Test, GST Ground Mode


Power Factor Test


Primarily stresses• Right-side bushing• Any right-side support



Power Factor Test

Open-Breaker UST Test, UST Mode

Measures• Contact assembly


Case 1 - Effect of Connected Bus

Bus Connected Bus DisconnectedBushing I (mA) Watts % PF I (mA) Watts % PF1 0.690 0.020 0.29 0.520 0.006 0.122 0.520 0.180 3.46 0.350 0.005 0.143 0.680 0.020 0.29 0.520 0.006 0.144 0.500 0.038 0.76 0.350 0.004 0.115 0.690 0.120 1.74 0.520 0.006 0.126 0.520 0.070 1.34 0.350 0.004 0.111 to 2 0.009 0.004 0.007 0.0013 to 4 0.008 0.004 0.007 0.0015 to 6 0.008 0.006 0.007 0.001

ABB 72 – PM – 31 – 12


Dead Tank SF6 with TRV Capacitors


Power Factor Test

Dead Tank SF6 Breaker with TRV Capacitors, Procedure 1a

• Bushings

- Hot-Collar

• Breaker



- 3 TRV capacitor USTs

Applies to all single-contact SF6 breakers.




Power Factor Test

Dead Tank SF6 Breaker with TRV Capacitors, Procedure 1a

Test Breaker HV LV Leads Test Mode CommentPosition Cable Red Blue

1 Open 1 Cap - GST Guard Red Blue1a Open 1 Cap - UST Measure Red Blue Capacitor2 Open 2 - - GST Ground Red Blue3 Open 3 Cap - GST Guard Red Blue3a Open 3 Cap - UST Measure Red Blue Capacitor4 Open 4 - - GST Ground Red Blue5 Open 5 Cap - GST Guard Red Blue5a Open 5 Cap - UST Measure Red Blue Capacitor6 Open 6 - - GST Ground Red Blue7 Open 1 Cap 2 UST Measure Blue Ground8 Open 3 Cap 4 UST Measure Blue Ground9 Open 5 Cap 6 UST Measure Blue Ground

Disconnect ground lead from base of each capacitor. This ground lead must beconnected before breaker is energized for service.



Power Factor Test


Power Factor Test

Dead Tank SF6 Circuit Breaker, Procedure 2

• Bushings

- Hot-Collar

• Breaker



- 3 closed-breaker tests

Applies to most multi-contact SF6 circuit breakers.



Power Factor Test


1 Open 1 - - GST Ground Red Blue2 Open 2 - - GST Ground Red Blue3 Open 3 - - GST Ground Red Blue4 Open 4 - - GST Ground Red Blue5 Open 5 - - GST Ground Red Blue6 Open 6 - - GST Ground Red Blue7 Open 1 2 - UST Measure Red Blue8 Open 3 4 - UST Measure Red Blue9 Open 5 6 - UST Measure Red Blue10 Closed 1 - - GST Ground Red Blue11 Closed 3 - - GST Ground Red Blue12 Closed 5 - - GST Ground Red Blue

Dead Tank SF6 Circuit Breaker, Procedure 2


Power Factor Test

Primarily stresses• Left-side bushing• Left-side support




Power Factor Test

Primarily stresses• Right-side bushing• Right-side support




Power Factor Test

Measures• Grading capacitors• Contact assemblies



Power Factor Test

Primarily stresses• Bushings• Support insulation• Operating rod• SF6 gas

Applies 10 kV directly to operating rod and additional support insulation.

Closed-Breaker Test, GST Ground Mode


It is necessary to address specific aspects of the analysis of resultsand investigation of questionable results, to include:

• Temperature correction

Results for SF6 circuit breakers not corrected for temperaturevariation

• Very low capacitance specimen

- current is 300 µA (80 pF) or less: evaluate dielectric loss

test performed at several voltages: evaluate dielectric lossand its increase

- current is greater than 300 µA (80 pF): evaluate power factorand capacitance

test performed at several voltages: evaluate power factor atlowest test voltage, power factor tip-up and capacitance

Analysis Policies - Dead Tank SF6 Breaker


Analysis - Dead Tank SF6 Breaker

Compare results:

• with factory data (acceptance test)

• with earlier tests (especially first acceptable test)

• among similar test specimens

- among similar tests

tests (1, 3 and 5) (2, 4 and 6) (7, 8 and 9) (10, 11 and 12)

- among phases

- among similar dead tank SF6 circuit breakers

• with Doble’s database and typical results (TDRB)



Tests 1 to 6

• Dominated by bushing

also includes operating rod, any support insulation and SF6 gas

• PF generally less than 1.0 %

Diagnostics

• High losses or high PF

degraded bushing, operating rod, support insulation, SF6 gas

- bushing Hot-Collar test

- test at several voltages (power factor tip-up)

- test SF6 gas for moisture content

- internal inspection



Tests 7, 8 and 9 (no grading capacitors)

• Condition of contact assembly (and SF6 gas)

• Very low current, evaluate losses

losses generally 0.010 Watts or less

Diagnostics

• High losses

degraded contact assembly


- test SF6 gas for moisture content




Tests 7, 8 and 9 (with grading capacitors)

• Dominated by grading capacitors

also includes contact assembly (and SF6 gas)


Diagnostic

• High PF

degraded capacitor, contact assembly


- test individual capacitors

- inspect contact assembly



Tests 10, 11 and 12 (most multi-contact breakers)

• Dominated by bushings

also includes operating rod, support insulation, SF6 gas

• PF is generally less than 1.0 %

Diagnostic

• High PF

degraded bushing, operating rod, support insulation, SF6 gas

- bushing Hot-Collar tests


- test SF6 gas for moisture



Surface conditions can be determined by performing a single Hot-Collar test with GST Ground mode (GND RB). Collar is normallyplaced underneath first skirt from line terminal.

• If losses are 0.10 Watt or less

surface conditions are acceptable

• If losses are higher than 0.10 Watt

clean weathershed and repeat Hot-Collar test

if necessary, repeat cleaning process and Hot-Collar test

It may be necessary to clean weathershed repeatedly. In somecases it may be necessary to clean weathershed with abrasivematerial.

High External Surface Losses


Case 2 - Breaker in Satisfactory Condition

Bkr Pos Test Ph Test 10 kV Equiv % PF corr CapkV I (mA) Watts meas corr factor (pF)

Open 1 1 10 0.518 0.005 0.10 0.10 1.00 138.752 1 10 0.444 0.005 0.11 0.11 1.00 117.653 2 10 0.526 0.006 0.11 0.11 1.00 140.904 2 10 0.444 0.006 0.14 0.14 1.00 119.655 3 10 0.525 0.007 0.13 0.13 1.00 140.406 3 10 0.444 0.006 0.14 0.14 1.00 118.95

Open 7 1 10 0.010 0.000 3.0008 2 10 0.011 0.000 3.1009 3 10 0.009 0.000 2.900

BBC 121 – PM – 40 – 20B


Case 3 - Damaged Contact Assembly

Bushing Test kV I (mA) Watts % PF1 10 0.599 0.042 0.702 10 0.650 0.030 0.463 10 0.595 0.016 0.274 10 0.651 0.010 0.155 10 0.594 0.016 0.276 10 0.651 0.017 0.261 to 2 10 0.023 0.0253 to 4 10 0.021 0.0015 to 6 10 0.021 0.001

ABB 242 – PMR – 40 – 20

Higher power factors for open-breaker tests 1 and 2, and especiallyhigh losses across contact assembly in same phase. Contactassembly damaged by lightning strike.


Case 4 - Deteriorated Grading Capacitor

Bushing Test kV I (mA) Watts % PF1 10 2.342 0.015 0.062 10 2.686 0.014 0.053 10 2.335 0.023 0.104 10 2.677 0.014 0.055 10 2.654 2.391 9.016 10 2.815 0.937 3.331 to 2 10 1.083 0.036 0.333 to 4 10 1.077 0.036 0.335 to 6 10 1.728 5.880 34.001 and 2 10 3.672 0.007 0.023 and 4 10 3.662 0.007 0.025 and 6 10 3.661 0.007 0.02

ABB 550 – PM – 40 – 30


Vacuum Circuit Breakers


Power Factor Test

Free Standing Vacuum Circuit Breaker Procedure

• Bushings

- Hot-Collar

• Breaker

- 6 open-breaker test


• Insulating mineral oil in interrupter compartment

Applies to all single-contact vacuum circuit breakers.


All tests with circuit breaker open.


Power Factor Test

Cubicle Vacuum Circuit Breaker Procedure

• Breaker



Applies to all single-contact vacuum circuit breakers.

All tests with circuit breaker open.


Power Factor Test

Vacuum Circuit Breaker



1 Open 1 - - GST Ground Red Blue2 Open 2 - - GST Ground Red Blue3 Open 3 - - GST Ground Red Blue4 Open 4 - - GST Ground Red Blue5 Open 5 - - GST Ground Red Blue6 Open 6 - - GST Ground Red Blue7 Open 1 2 - UST Measure Red Blue8 Open 3 4 - UST Measure Red Blue9 Open 5 6 - UST Measure Red Blue


Power Factor Test

Primarily stresses• Left-side bushing• Operating rod• Any support insulation• Any phase barrier• Any insulating oil



Power Factor Test

Primarily stresses• Right-side bushing• Any support insulation• Any phase barrier• Any insulating oil



Power Factor Test

Measures• Vacuum interrupter• Any phase barrier• Any insulating oil





Results vacuum circuit breakers not corrected for temperaturevariation





test performed at several voltages: evaluate power factor atlowest test voltage, power factor tip-up and capacitance

Analysis Policies - Vacuum


Analysis of Results - Vacuum

Compare results:





tests (1, 3 and 5) (2, 4 and 6) (7, 8 and 9)

- among phases

- among similar vacuum circuit breakers




Tests 1 to 6


also includes operating rod, any support insulation, any phasebarrier, any mineral oil


Diagnostic


degraded bushing, operating rod, support insulation, phasebarrier, insulating mineral oil

- bushing Hot-Collar test

- test insulating mineral oil in interrupter compartment




Tests 7, 8 and 9

• Vacuum interrupter

also includes any phase barriers and any mineral oil


losses generally 0.010 Watts or less

Diagnostic

• High losses

degraded vacuum interrupter, any phase barrier, any mineral oil

- test any insulating mineral oil in interrupter compartment

- clean vacuum interrupter

- remove any phase barriers

- also, perform AC or DC high-potential test


Case 5 - Deteriorated Bushing

Bushing Test kV I (mA) Watts % PF1 10 0.238 0.037 1.552 10 0.223 0.039 1.753 10 0.236 0.033 1.404 10 0.224 0.049 2.195 10 0.239 0.035 1.466 10 0.221 0.038 1.72

1 to 2 10 0.047 0.0033 to 4 10 0.047 0.0025 to 6 10 0.047 0.002


Oil Circuit Breakers


Oil Circuit Breaker

• Bushings

- C1 insulation

- C2 insulation

- Hot-Collar

• Breaker


- 3 closed-breaker tests

- calculate tank-loss index

• Insulating mineral oil

Power Factor Test


Oil Circuit Breaker

No test or ground lead connected to remaining bushings.

Power Factor Test


1 Open 1 - - GST Ground Red Blue2 Open 2 - - GST Ground Red Blue3 Open 3 - - GST Ground Red Blue4 Open 4 - - GST Ground Red Blue5 Open 5 - - GST Ground Red Blue6 Open 6 - - GST Ground Red Blue7 Closed 1 - - GST Ground Red Blue8 Closed 3 - - GST Ground Red Blue9 Closed 5 - - GST Ground Red Blue


GST Ground

Meter

Stresses• Bushing• Contact assembly• Guide assembly• Upper portion of lift rod

Open-Breaker Test


GST Ground

Meter Oil

Stresses• Bushings• Contact assemblies• Lower portion of lift rod• Any tank liner• Oil

Closed-Breaker Test


Analysis Policies - Oil Circuit Breaker


• Tank Loss Index


Results for most oil circuit breakers corrected for temperaturevariation

• Peculiarities

- high external surface losses across upper weathershed

- high external surface losses across lower insulation


Primary contributors to lossesOpen-Breaker Test Closed-Breaker Test

• Bushing • Bushings• Contact assembly • Contact assemblies• Guide assembly • Lower portion of lift rod• Upper portion of lift rod • Any tank liner

• Oil

Lessor contributors to lossesOpen-Breaker Test Closed-Breaker Test

• Any tank liner • Guide assembly• Oil

Tank Loss Index


Tank Loss Index

• Open-breaker and especially closed-breaker power factorsdominated by bushings

• Created to analyze condition of remaining insulation

• Calculated for each phase

• Not affected by bushing surface conditions

assuming same surface conditions for Open- and Closed tests


Negative TLI Positive

Contact assemblies Lower portion of lift rodGuide assembly,especially any cross-guide

Any tank linerOil

Upper portion of lift rod

Guidelines for investigating abnormal TLI for oil circuit breakersWatts, referenced to 10 kV

< - 0.20 < - 0.10 to - 0.20 - 0.10 to + 0.05 > + 0.05 to + 0.10 > + 0.10investigate retest normal for most

breakersretest investigate

Tank Loss Index

TLI = Closed-Breaker Losses - Sum of Open-Breaker Losses


Tank Loss Index

What happens to TLI if:

• Water enters oil… swings positive

• Water enters contact assemblies... swings negative

• Water and carbon collect on lift rod... swings positive

• Water saturates tank liner... swings positive


Temperature Correction

Power factors are corrected to a reference temperature of 20°Cusing the following guidelines.

• Bushings

correct C1 insulation power factor using ambient temperature

C2 power factor is not corrected for temperature variation

• Breaker

correct power factor using ambient temperature and bushingpower factor-temperature characteristic

• Insulating mineral oil

correct power factor using oil temperature and oil power factor-temperature characteristic


TABLE OF MULTIPLIERS FOR USE IN CONVERTING POWER FACTOR ATTEST TEMPERATURES TO POWER FACTORS AT 20°C

ABB HAEFELY LAPPTest Type Type Types Class Class

Temperature T O + C COT,COS PRC POC°C °F SOT 15-69 kV 15-765 kV0 32.0 1.02 .87 - .81 1.004 39.2 1.02 .91 - .86 1.008 46.4 1.01 .93 - .89 1.00

12 53.6 1.01 .95 .90 .94 1.0016 60.8 1.00 .98 .95 .97 1.0020 68.0 1.00 1.00 1.00 1.00 1.0024 75.2 1.00 1.02 1.04 1.03 1.0028 82.4 .99 1.04 1.09 1.07 1.0032 89.6 .97 1.06 1.13 1.11 1.0036 96.8 .96 1.07 1.17 1.13 1.0040 104.0 .94 1.08 1.21 1.15 1.0044 111.2 .91 1.10 1.24 1.15 1.0048 118.4 .87 1.11 126 1.14 1.0052 125.6 .84 1.11 1.28 1.11 1.0056 132.8 .79 1.11 1.30 1.07 1.0060 140.0 .75 1.12 1.27 1.05 1.00



TABLE OF MULTIPLIERS FOR USE IN CONVERTING POWER FACTOR ATTEST TEMPERATURES TO POWER FACTORS AT 20°C

Test ConventionalTemperature Insulating Oil°C °F0 32.0 1.564 39.2 1.488 46.4 1.43

12 53.6 1.3116 60.8 1.1620 68.0 1.0024 75.2 .8328 82.4 .7032 89.6 .5836 96.8 .4940 104.0 .4244 111.2 .3648 118.4 .3052 125.6 .2656 132.8 .2160 140.0 .17



Analysis of Results - Oil Circuit Breaker

Compare results:





▪ open-breaker tests

▪ closed-breaker tests

- among phases (including TLIs)

- among similar oil circuit breakers



Analysis of Results - Oil Circuit Breaker

In general, an oil circuit breaker is in satisfactory condition when itmeets the following criteria:

• Open-breaker power factors approximate respective bushing C1power factor

• Closed-breaker power factors approximate average of 2respective bushing C1 power factors

• TLI’s are in range of - 0.10 to + 0.05 Watts


Tank Loss Index

Bushing C1 Insulation TestsBushing I (mA) Watts % PF

1 1.024 0.027 0.262 1.016 0.025 0.25

Breaker TestsBreakerPosition

Bushing I (mA) Watts % PF

Open 1 1.152 0.034 0.30Open 2 1.154 0.032 0.28

Closed 1 and 2 2.204 0.058 0.26TLI = – 0.008 Watts

Example 1, acceptable condition

Comment: Bushing C1 insulation power factors, open- and closed-breaker power factors and TLI are acceptable


Tank Loss Index


1 1.024 0.027 0.262 1.016 0.094 0.93



Open 1 1.152 0.034 0.30Open 2 1.154 0.101 0.88


Example 2, deteriorated No. 2 bushing

Comment: High No. 2 bushing C1 insulation power factor and HighNo. 2 open-breaker power factor with acceptable TLI.


Tank Loss Index

Example 3, deteriorated contact assemblies, guide assembly andupper portion of lift rod

Comment: High No. 2 open-breaker power factor and highnegative TLI.


1 1.024 0.027 0.262 1.016 0.025 0.25



Open 1 1.152 0.132 1.15Open 2 1.154 0.135 1.17



Tank Loss Index

Example 4, deteriorated lower portion of lift rod, tank liner and oil

Comment: High positive TLI. Test oil.


1 1.024 0.027 0.262 1.016 0.025 0.25



Open 1 1.152 0.054 0.47Open 2 1.154 0.049 0.42

Closed 1 and 2 2.204 0.227 1.03TLI = + 0.124 Watts


Tank Loss Index

Example 5, general contamination of internal insulation

Comment: High open- and closed-breaker power factors withacceptable TLI. Surface contamination of bushings? Probably not.Hot-Collar test. Test oil.


1 1.024 0.027 0.262 1.016 0.025 0.25



Open 1 1.152 0.172 1.49Open 2 1.154 0.167 1.45

Closed 1 and 2 2.204 0.372 1.69TLI = + 0.033 Watts


Case 6 - Breaker Not Completely Closed

Test BreakerPosition


1 Open 1 0.282 0.035 1.22 Open 2 0.294 0.038 1.33 Open 3 0.283 0.029 1.04 Open 4 0.303 0.041 1.45 Open 5 0.279 0.035 1.26 Open 6 0.303 0.040 1.37 Closed 1 and 2 0.715 0.081 1.08 Closed 3 and 4 0.722 0.076 1.19 Closed 5 and 6 0.455 0.420 9.2

TLI (Watts), Phase 1 = + 0.008, Phase 2 = + 0.006, Phase 3 = +0.345 Breaker did not close properly.


Diagnostic Test on Interrupter

2 kV Power Factor Guidelines

Good 10 - 30 %

Questionable 30 - 50

Bad > 50


Diagnostic Test on Wood Components

Material Maximum Limitfor two 3-inch sections

Watts at 10 kV MW at 2.5 kVvarnish woodor plastic-covered components

0.25 15

epoxy-fiber components 0.10 6


Power Factor Test - Oil Circuit Breaker

Summary

• Measure bushing C1 and C2 power factors

and hot-collar losses

• Measure open- and closed-breaker power factors

power factor corrected to 20°C using ambient temperature andbushing characteristic

calculate TLI for each phase

• Measure oil power factor

power factor corrected to 20°C using oil temperature and oilcharacteristic

• Analyze results

perform necessary diagnostic tests


Air-Magnetic Circuit Breakers

Westinghouse Type DHP, 13.8 kV



• 6 Open-breaker Guard tests

• 3 Open-breaker USTs


Power Factor Test




Power Factor Tests - Air-Magnetic

Test Breaker HV LV Lead Test ModePosition Cable Red Blue

1 Open 1 2 - GST Guard Red Blue2 Open 2 1 - GST Guard Red Blue3 Open 3 4 - GST Guard Red Blue4 Open 4 3 - GST Guard Red Blue5 Open 5 6 - GST Guard Red Blue6 Open 6 5 - GST Guard Red Blue7 Open 1 2 - UST Measure Red Blue8 Open 3 4 - UST Measure Red Blue9 Open 5 6 - UST Measure Red Blue




Results for air-magnetic circuit breakers not corrected fortemperature variation





test performed at several voltages: evaluate power factormeasured at lowest test voltage, power factor tip-up andcapacitance

Analysis Policies - Air-Magnetic


• Abnormally low or negative power factor

Analysis Policies - Air-Magnetic


Analysis of Results - Air-Magnetic

Compare results:





tests (1, 3 and 5) (2, 4 and 6) (7, 8 and 9)

- among phases

- among similar air-magnetic circuit breakers




Tests 1 to 6


also includes operating rod, puffer assembly, phase barrier,auxiliary insulation

Diagnostic


degraded bushing, operating rod, puffer assembly, phasebarrier, auxiliary insulation

- repeat tests with phase barriers and arc-chute removed



Tests 7, 8 and 9

• Arc-chute and phase barrier


Diagnostic

• High losses

- clean and dry arc-chutes and phase barriers


Case 7 - Deteriorated Air-Magnetic Breaker

Bushing Test kV I (mA) Watts % PF1 10 1.023 0.952 9.312 10 1.007 0.378 3.753 10 0.992 0.645 6.504 10 1.047 0.363 3.475 10 0.856 0.442 5.166 10 1.092 0.569 5.211 to 2 10 0.148 0.4183 to 4 10 0.154 0.4535 to 6 10 0.175 0.648

General Electric Type AM, 13.8 kV. Maximum limits are 5.0 % for bushing PF’s and0.50 Watts for arc-chute losses.


Live-Tank Circuit Breakers


I-Module Live-Tank Circuit Breakers


Single I-Module Circuit Breaker

• 1 interrupter chamber test

• 1 column test


Power Factor Test, Single I-Module



C1 = Interrupter chamberS1C = Support insulatorS1R = Operating rod

Test Breaker HV LV Leads Test Mode InsulationPosition Cable Red Blue

1 Open B A - UST Measure Red Ground Blue C12 Open B A - GST Guard Red Blue S1C + S1R

3 Open B A - GST Ground Red Blue C1 + (S1C + S1R)



Test 1

UST Measure Red Blue



Test 2

GST Guard Red Blue


Power Factor Test, Single T- and Y-Module

ABB Type HPL-362-A2, 362 kV


Single T- or Y-Module Circuit Breaker

• 2 interrupter chamber and grading capacitor tests

• 1 column test





C1, C2 = Interrupter chambersGC1, GC2 = Grading capacitors

S1C = Support insulatorS1R = Operating rod

Test Breaker HV LV Leads Test Mode InsulationPosition Cable Red Blue

1 Open D A B UST Measure Red Ground Blue C1 + GC12 Open D A B UST Measure Blue Ground Red C2 + GC23 Open D A B GST Guard Red Blue S1C + S1R


Test 1

UST Measure Red Ground Blue



Test 2

UST Measure Blue Ground Red



Test 3

GST Guard Red Blue



Reyrolle 500 kV

Power Factor Test, Multiple-Module


Multiple T- or Y-Module Circuit Breaker

• Test each interrupter chamber (normally by UST)

• Test each column (normally by GST Guard)

• Test each operating rod if separated from column




Complex Live-Tank Circuit Breakers

BBC Type DLF

Tests 1 to 4 measure interrupter chambers.Test 5 measures column.

Test Energize Ground Guard UST1 B C, F A2 B A, F C3 D E, F C4 D C, F E5 F B, D



Results for live-tank circuit breakers not corrected fortemperature variation. An exception is grading capacitorassemblies for General Electric 115/230/345-kV type ATBbreakers.



test performed at several voltages: evaluate dielectric lossand its increasec


test performed at several voltages: evaluate power factormeasured at lowest test voltage, power factor tip-up andcapacitance

Analysis Policies - Live-Tank


• Abnormally low or negative power factor

investigate electrostatic interference effect

Analysis Policies - Live-Tank


High Levels of Electrostatic Interference

M2H instrument

• Shielding

• Line synchronized reversal

Average of normal and 180° reversed readings at 60 Hz. Is onlyeffective when specimen current is greater than interferencecurrent.

• Polarity indicator

• Interference cancellation circuit (ICC)


High Levels of Electrostatic Interference

M4000 instrument

• Shielding

• Line synchronized reversal

Average of normal and 180° reversed readings at 60 Hz. Is onlyeffective when specimen current is greater than interferencecurrent.

• Line frequency modulation

Average of two readings at ±5% (or ±10%) of the line frequency,e.g. 57 and 63 Hz. This method minimizes effects ofelectrostatic interference and yields superior results in highlevels of electrostatic interference.


Compare results:





- among similar phases

- among similar circuit breakers


Analysis of Results - Live-Tank Breaker



Interrupter chamber (with grading capacitor)

• dominated by grading capacitor

also includes interrupter chamber and any resistor switchchamber

• Power factor generally less than 1.0 %

Diagnostic

• High power factor

degraded grading capacitor, interrupter chamber, resistor switchchamber

- test separately grading capacitor, interrupter chamber andresistor switch chamber



Interrupter chamber (no grading capacitor)

• Includes interrupter chamber, any resistor switch chamber


• Losses generally 0.020 Watts or less

Diagnostic

• High losses

degraded interrupter chamber, resistor switch chamber

- test separately interrupter chamber, resistor switch chamber



Columns


• Losses generally 0.030 Watts or less

• Very sensitive to external surface conditions

Diagnostic

• High losses

- perhaps operate breaker and re-test

- test individual column sections

- check for leaks



C1 C2

S1Test Ph Insul Test I (mA) Watts % PF Cap

kV (pF)1 A C1 10 3.801 0.165 0.43 12092 A C2 10 3.811 0.169 0.44 12133 A S1 10 0.196 0.011 624 B C1 10 3.818 0.190 0.50 12155 B C2 10 3.823 0.187 0.49 12166 B S1 10 0.199 0.012 637 C C1 10 3.830 0.205 0.54 12198 C C2 10 3.809 0.369 0.97 12129 C S1 10 0.187 0.008 59

AEG Type S2 – 420, 420 kV



C1 C2

S1Individual grading capacitor tests

Test Phase Capacitor 2 kV 10 kV % PF% PF % PF Tip-Up

1 A C2 0.42 0.42 0.002 B C2 0.46 0.46 0.003 C C2 1.20 0.97 - 0.23

C-phase C2 grading capacitor was replaced

AEG Type S2 – 420, 420 kV


Case 9 - Contaminated SF6 Gas

Siemens 3AT5, 500 kV

Column Test kV I (mA) Watts1 10 0.160 0.0182 10 0.155 0.0123 10 0.161 0.0104 10 0.158 0.0085 10 0.160 0.1806 10 0.166 0.160

Gas PurityColumns 1 and 2 99.7 %Columns 3 and 4 99.5 %Columns 5 and 6 91.7 %


Case 9 - Contaminated SF6 Gas

After 24-hour vacuum and SF6 gas restored to better than 99 %pure.

Column Test kV I (mA) Watts5 10 0.173 0.0246 10 0.175 0.032

Siemens 3AT5, 500 kV


Complex Dead Tank SF6 Circuit Breakers

ABB PASS circuit breaker, includes a circuit breaker, disconnector, ground switch and metering unit


Current Transformers


Power Factor Test

Routine procedure is determined by the type of insulation andwhether it has a tap:

• liquid- and gas-filled

- no tap

▪ Overall

▪ Hot-Collar

- with tap

▪ Overall

▪ C1 insulation

▪ C2 insulation

▪ Hot-Collar


Power Factor Test

• dry-type

- Overall at several voltages


Complex Dead Tank SF6 Circuit Breakers

ABB PASS Circuit breaker, included circuit breaker, disconnector, ground switch and metering unit


ABB PASS M0 Circuit breaker, included circuit breaker, disconnector and ground switch

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