Power Factor Testing Circuit Breakers Part 1 2007 Conference

Doble® Testing Circuit Breakers, Part 1Dead-Tank SF6, Vacuum and Live-Tank Circuit Breakers

Gary HeustonDoble Engineering Company

April 23, 2007 2007 Doble® Client Conference2

PROPRIETARY INFORMATION

Doble Engineering Company (“Doble®”), has full title, right and interest to all subject matter contained in this presentation (“Proprietary Information”) regardless of the medium. You have been provided a copy of this Proprietary Information for private reference purposes only. Doble’s delivery to you of Doble® Proprietary Information does not constitute in any way whatsoever a license of any kind or vests any interest in Doble’s Proprietary Information (other than private reference use), including, without limitation, the rights to copy, disseminate, distribute, transmit, display or perform in public (or to third parties), reproduce, edit, translate or reformat. You, as recipient, acknowledge and agree to these terms by your first viewing of this Proprietary Information. You further acknowledge and agree that Doble® shall not have an adequate remedy at law in the event of your breach of the conditions hereunder, that Doble® will suffer irreparable damage and injury if you breach any of the conditions stated above, and that such breach occurs, Doble®, in addition to any other rights and remedies available herein or otherwise, shall be entitled to seek an injunction to be issued by a tribunal of competent jurisdiction restricting the recipient from committing or continuing any breach of these conditions.


Circuit Breakers


Agenda

• Terminology• Circuit breaker tests• Power factor test

- applicable policies- procedures- analysis of results- diagnostic tests


Agenda

• Case studiesPart 1- 1: effect of connected bus- 2: SF6 breaker in satisfactory condition- 3: damaged contact assembly- 4: deteriorated grading capacitor dead tank SF6

breaker- 5: deteriorated bushing in vacuum breaker- 6: deteriorated grading capacitor- 7: contaminated SF6 gas in live tank breaker


Agenda

Part 2- 1: oil breaker not completely closed- 2: deteriorated air-magnetic breaker


Dead-Tank Versus Live-Tank

• Dead tank switching deviceSwitching device in which a vessel(s) at ground potential surrounds and contains interrupter(s) and insulating medium.

• Live tank switching deviceSwitching device in which the vessel(s) housing the interrupter(s) is at a potential above ground.

Source: IEEE Dictionary

April 23, 2007 2007 Doble® Client Conference9Dead-Tank Circuit Breakers


Dead-Tank Circuit Breakers


Live-Tank Circuit Breakers


Bushing Numbers

1 2


Bushing Numbers

42 61 3 5


Bushing Numbers

1 3 52 4 6


Circuit Breaker Tests

Routinely includes these measurements:• Power factor and capacitance

- 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 and polarization index (IR10/IR1)

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

• High-potential on vacuum circuit breakers


Power Factor Tests

The different vessel types and arrangements, different operating principles and internal construction, and different interrupting methods and mediums complicate the testing of circuit breakers.Any procedure should include these features:• Stresses all insulating components, to include

entrance bushings, interrupter assemblies, insulated operating rods and any grading capacitors.

• Divides specimen into its major components.• Increases sensitivity to localized conditions and

assist in locating contamination and deterioration.


Power Factor Tests

• Provides more effective analysis of results.• Includes numerous checks to heighten confidence

level.


Dead-Tank SF6 Circuit Breakers


Power Factor Tests, Procedure 1

Dead Tank SF6 Circuit Breakers• Bushings

Hot-Collar• Breaker

- 6 open-breaker tests- 3 open-breaker USTs

Applies to most single-contact and some multi-contact SF6 breakers.Inherently low losses require bus disconnected.All tests with breaker open.


Test Procedure 1

Dead Tank SF6 Circuit Breakers, Procedure 1

Isolate remaining bushingsTests 1 to 6 don’t require a low-voltage lead; Tests 7 to 9 require one low-voltage lead.

Breaker HV LV LeadsTest Position Cable Red Blue Test Mode

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 Ground Blue8 Open 3 4 - UST Measure Red Ground Blue9 Open 5 6 - UST Measure Red Ground Blue


Test Policies

Necessary to address specific aspects of this testing, to include:• Inherently low losses »• Applied test voltage

routinely 10 kV• Temperature correction

power factor not corrected for temperature variation• Very low capacitance specimens


Inherently Low Losses

Isolate circuit breaker from system


Case 1: Effect of Connected Bus

Bus Connected Bus DisconnectedBushing I (mA) Watts % PF I (mA) Watts % PF

1 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 0.11

1 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


Test Policies

• Inherently low losses• Applied test voltage


power factor not corrected for temperature variation• Very low capacitance specimens »


Very Low Capacitance Specimens

• Current is greater than 300 µA (80 pF): evaluate power factor and capacitancetest performed at several voltages: evaluate power factor at lowest test voltage, power factor tip-up and capacitance

• Current is 300 µA (80 pF) or less: evaluate dielectric losstest performed at several voltages: evaluate dielectric loss and its increase


Test Procedure 1


Isolate remaining bushingsTests 1 to 6 don’t require a low-voltage lead; Tests 7 to 9 require one low-voltage lead.




Open-Breaker GST Test

Primarily stresses• Left-side bushing• Operating rod• SF6 gas



Primarily stresses• Right-side bushing• Support insulation• SF6 gas


Open-Breaker UST Test

Measures• Contact assembly• SF6 gas


Higher Voltage Dead-Tank Breakers


Power Factor Tests, Procedure 2

Dead Tank SF6 Circuit Breakers• Bushings


- 6 open-breaker tests- 3 open-breaker USTs- 3 closed-breaker tests

Applies to most multi-contact SF6 circuit breakers.Inherently low losses require bus disconnected.


Test Procedure 2


10 Closed 1 - - GST Ground Red Blue11 Closed 3 - - GST Ground Red Blue12 Closed 5 - - GST Ground Red Blue





Primarily stresses• Left-side bushing• Left-side support insulation• SF6 gas



Primarily stresses• Right-side bushing• Right-side support insulation• SF6 gas



Measures• Grading capacitors• Contact assemblies• SF6 gas


Closed-Breaker GST Test

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

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


Analysis

Power factor compared with:• Initial test

- purchase specification- manufacturer’s specification- similar insulation specimens

tests with similar current and capacitance▪ tests 1, 3 and 5▪ tests 2, 4 and 6▪ tests 7, 8 and 9▪ tests 10, 11 and 12

- similar breakers- Doble’s typical results and database


Analysis

Power factor compared with:• Later tests compared with initial test value

Questionable results in later tests- manufacturer’s specification- Doble’s typical results and database


Tabulated Results

Open-Breaker GST Tests Equivalent 10-kV Watts-Loss at Test Temperature

Open-Breaker UST Tests Equivalent 10-kV Watts-Loss at Test Temperature Rated No. of 0 .005 .010 .016 .021 .026 .031 .036 .041 .046

System Test Units to to to to to to to to to andMfr. Type kV kV Tested .004 .009 .015 .020 .025 .030 .035 .040 .045 up

W SP 15.5 10 6 638 10 36 33 3

Rated No. of 0 .005 .010 .016 .021 .026 .031 .036 .041 .046System Test Units to to to to to to to to to and

Mfr. Type kV kV Tested .004 .009 .015 .020 .025 .030 .035 .040 .045 upS SP 38 10 171 60 95 11 2 1 1

48.3 10 198 30 84 31 18 10 1 2472.5 10 703 155 464 67 15 2

W SP 15.5 10 12 6 638 10 223 50 110 52 10 146 10 36 6 23 7

72.5 10 330 81 96 102 14 17 6 4 5 5

S SP 38 10 132 120 10 1 148.3 10 87 8772.5 10 160 158 2

46 10 9 6 2 172.5 10 66 58 7 1


Tabulated Results

Open-Breaker GST Tests Equivalent 10-kV Watts-Loss at Test Temperature

Open-Breaker UST Tests Equivalent 10-kV Watts-Loss at Test Temperature Rated No. of 0 .005 .010 .016 .021 .026 .031 .036 .041 .046

System Test Units to to to to to to to to to andMfr. Type kV kV Tested .004 .009 .015 .020 .025 .030 .035 .040 .045 up

242PA40-20 242 10 36

Rated No. of 0 .005 .010 .016 .021 .026 .031 .036 .041 .046System Test Units to to to to to to to to to and

Mfr. Type kV kV Tested .004 .009 .015 .020 .025 .030 .035 .040 .045 upBBC 72PM31-20 72.5 10 42 13 21 8

121PA40-20 121 10 360 149 162 26 8 7 8145PA40-20 145 10 180 84 60 24 9 1 2242PA40-20 242 10 96 48 47 1

BBC 72PM31-20 72.5 10 21121PA40-20 121 10 86 32 1 1 1145PA40-20 145 10 30 3 3 3 1 4 4


Analysis

Capacitance compared with:• Initial test

- similar breakers- Doble’s database

• Later tests compared with initial test value (% diff.)- good less than 5 %- deteriorated from 5 % to less than 10 %- investigate 10 % and higher


Analysis: Tests 1 to 6

• Dominated by bushingalso includes operating rod, any support insulation and SF6 gas

• Power factor generally less than 1.0 %



Diagnostics• High losses or high power factor

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, purity, acidity and arc by-

products- internal inspection


Analysis: Tests 7, 8 and 9

Breakers without grading capacitors• Condition of contact assembly (and SF6 gas)• Very low current, evaluate losses

losses generally 0.010 Watts or lessDiagnostics• High losses

degraded contact assembly- test at several voltages (power factor tip-up)- test SF6 gas for moisture, purity, acidity and arc by-




Breakers with grading capacitors• Dominated by grading capacitors

also includes contact assembly (and SF6 gas)• Power factor generally less than 1.0 %Diagnostics• High power factor

- degraded capacitor, contact assembly- test at several voltages (power factor tip-up)- test individual capacitors- inspect contact assembly



(most multi-contact breakers)• Dominated by bushings

also includes operating rod, support insulation, SF6 gas

• PF is generally less than 1.0 %



Diagnostics• High PF

degraded bushing, operating rod, support insulation, SF6 gas- bushing Hot-Collar tests- test at several voltages (power factor tip-up)- test SF6 gas for moisture, purity, acidity and arc by-



Diagnostic Tests

Perform when questionable results are measured for routine tests. Questionable results include high, abnormally low or negative power factor. Also, low or high capacitance.

Diagnostic tests include:• Hot-Collar test

detects localized condition and monitors surface losses

• Test at several voltages (power factor tip-up)detects voltage sensitive condition, e.g. carbonized path


High External Surface Losses

Surface conditions are qualified with a 10 kV Hot-Collar test using GST Ground mode (GND RB). Single collar placed underneath first skirt from line terminal.• Losses are 0.10 Watt or less

surface conditions are acceptable• Losses are higher than 0.10 Watt

- clean weathershed and repeat Hot-Collar test- if necessary, repeat cleaning process and Hot-

Collar test- may be necessary to clean weathershed with

abrasive material



HV LV LeadsCable Red Blue Test ModeCollar C. Conductor - GST Ground Red Blue



Suggested cleaning methods and cleaning agents include:• Dry clean cloth• Water and soap• Colonite™• Ammonia-based cleaners

Highly evaporative cleaners like alcohol may cool surface, causing moisture to condense on surface. This increases surface losses.


Case 2: Typical Results

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

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 0.26

1 to 2 10 0.023 0.0253 to 4 10 0.021 0.0015 to 6 10 0.021 0.001

Higher power factors for open-breaker tests 1 and 2, and especially high losses across contact assembly in same phase. Contact assembly damaged by lightning.

ABB 242 – PMR – 40 – 20


Case 4: Deteriorated Capacitor


1 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 34.00

1 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



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



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


Circuit Breakers with External Line-to-Ground Capacitors


External Line-to-Ground Capacitors

Per ABB:• Breakers with interrupting ratings of 50 kA and 63 kA

require external line-to-ground capacitors.• Enable the breaker to achieve 90 percent short-line

fault (SLF) interrupting capability.• Cause a time delay in the initial rate of rise of the

recovery voltage of the line side component of the Transient Recovery Voltage, i.e. the rate of rise is less severe.

• Certain applications require capacitors be placed on both sides of the breaker, e.g. a tie breaker.



Procedure for 138 kV ABB circuit breaker with external line-to-ground capacitors• Bushings


- 6 open-breaker tests- 3 open-breaker USTs- 3 line-to-ground capacitor USTs

Inherently low losses require bus disconnected.All tests with breaker open.



Procedure for 138 kV ABB Breaker with Line-to-Ground Capacitors

Breaker HV LV LeadsTest Position Cable Red Blue Test Mode Comment

1 Open 1 Cap - GST Guard Red Ground Blue1A Open 1 Cap - UST Measure Red Ground Blue Capacitor2 Open 2 - - GST Ground Red Blue3 Open 3 Cap - GST Guard Red Ground Blue

3A Open 3 Cap - UST Measure Red Ground Blue Capacitor4 Open 4 - - GST Ground Red Blue5 Open 5 Cap - GST Guard Red Ground Blue

5A Open 5 Cap - UST Measure Red Ground Blue Capacitor6 Open 6 - - GST Ground Red Blue7 Open 1 Cap 2 UST Measure Red Ground Blue8 Open 3 Cap 4 UST Measure Red Ground Blue9 Open 5 Cap 6 UST Measure Red Ground Blue

Disconnect ground lead from base of each capacitor. This ground lead must be connected before breaker is energized for service. Isolate remaining bushings.


Vacuum Circuit Breakers


Power Factor Tests

Free-Standing Vacuum Circuit Breaker• Bushings


- 6 open-breaker test- 3 open-breaker USTs

• Insulating oil in interrupter compartment

Applies to all single-contact vacuum circuit breakers.Inherently low losses require bus disconnected.All tests with circuit breaker open.


Power Factor Tests

Cubicle Vacuum Circuit Breaker• 6 open-breaker tests• 3 open-breaker USTs

Applies to all single-contact vacuum circuit breakers.All tests with circuit breaker open.


Test Procedure



Isolate remaining bushings.Tests 1 to 6 don’t require a low-voltage lead; Tests 7 to 9 require one low-voltage lead.


Test Policies

Necessary to address specific aspects of this testing, to include:• Inherently low losses

isolate circuit breaker from system• Applied test voltage »• Temperature correction



Applied Test Voltage

Breaker Rated kV Routine Test kV15 kV class 10includes 12.47, 13.2, 13.8, 14.4 kV8 kV class 7.5includes 6.9, 7.2 kV5 kV class 5includes 4.16 Kv


Test Policies

• Inherently low lossesisolate circuit breaker from system

• Applied test voltage• Temperature correction



Test Procedure



Isolate remaining bushings.Tests 1 to 6 don’t require a low-voltage lead; Tests 7 to 9 require one low-voltage lead.



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



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



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


Analysis


- purchase specification- manufacturer’s specification- similar insulation specimens

tests with similar current and capacitance▪ tests 1, 3 and 5▪ tests 2, 4 and 6▪ tests 7, 8 and 9

- similar breakers- Doble’s typical results and database


Analysis

• Later tests compared with initial test valueQuestionable results in later tests- manufacturer’s specification- Doble’s typical results and database


Analysis



• Later tests compared with initial test value (% diff.)- Good less than 5 %- deteriorated from 5 % to less than 10 %- investigate 10 % and higher



• Dominated by bushingalso includes operating rod, any support insulation, any phase barrier, any mineral oil

• Power factor generally less than 2.0 %Diagnostics• High power factor or high losses

degraded bushing, operating rod, support insulation, phase barrier, insulating mineral oil- bushing Hot-Collar test- test insulating oil in interrupter compartment- internal inspection



• Vacuum interrupteralso includes any phase barriers and any oil

• Very low current, evaluate losseslosses generally 0.010 Watts or less



Diagnostics• High losses

degraded vacuum interrupter, any phase barrier, any 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


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


Vacuum Circuit Breaker Failure


Test Policies

Necessary to address specific aspects of this testing, to include:• Applied test voltage


power factor not corrected for temperature variationException: power factor and capacitance for grading capacitor assemblies in Pre-model 7 General Electric 115/230/345-kV type ATB breakers.

• Very low capacitance specimens »• High levels of electrostatic interference


Very Low Capacitance Specimens

• Current is greater than 300 µA (80 pF): evaluate power factor and capacitancetest performed at several voltages: evaluate power factor at lowest test voltage, power factor tip-up and capacitance

• Current is 300 µA (80 pF) or less: evaluate dielectric losstest performed at several voltages: evaluate dielectric loss and its increase


Test Policies

• Applied test voltageroutinely 10 kV

• Temperature correctionpower factor not corrected for temperature variationException: power factor and capacitance for grading capacitor assemblies in Pre-model 7 General Electric 115/230/345-kV type ATB breakers.

• Very low capacitance specimens• High levels of electrostatic interference »


High Electrostatic Interference



• The lower the specimen current the greater the deleterious effect of electrostatic interference.Tests that do not include a grading capacitor are normally very low capacitance specimen, e.g column test.

• Electrostatic interference can cause abnormally high or low or negative Watts and power factor.



M2H instrument• Shielding• Line synchronized reversal

Average of normal and 180° reversed readings at 60 Hz. Is only effective when specimen current is greater than interference current.

• Polarity indicator• Interference cancellation circuit (ICC)

Required when specimen current is relatively high compared to interference current.



M4000 instrument• Shielding• Line synchronized reversal

Average of normal and 180° reversed readings at 60 Hz. Is only effective when specimen current is greater than interference current.

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


I-Modular Live-Tank Breakers


I-Module Breaker Test Procedure

• 1 interrupter chamber test• 1 operating rod and column insulation test

All tests with breaker open.


I-Module Breaker Test Procedure

Breaker HV LV Leads

Test Position Cable Red Blue Test Mode Insulation

C1

S1C + S1R

C1 + (S1C + S1R)

1 Open B A - UST Measure Red Ground Blue

2 Open B A - GST Guard Red Ground Blue

3 Open B A - GST Ground Red Blue

Operating rod=S1RSupport insulator=S1CInterrupter chamber=C1


Test 1: Interrupter Chamber

UST Measure Red Ground Blue (UST R)


Test 2: Column

GST Guard Red Ground Blue (GAR R)


T- and Y-Module Live-Tank Breakers


T- and Y-Module Test Procedure

• 2 interrupter chamber and grading capacitor tests• 1 operating rod and column insulation test




Breaker HV LV Leads

Test Position Cable Red Blue Test Mode Insulation

C1 + GC1

C2 + GC2

S1C + S1R

1 Open D A B UST Measure Red Ground Blue

2 Open D A B UST Measure Blue Ground Red

3 Open D A B GST Guard Red Blue

Operating rod=S1RSupport Insulator=S1CGrading Capacitors=GC1,GC2Interrupter chambers=C1,C2


Interrupter Chambers and Grading Capacitors



UST Measure Red Ground Blue (UST R)



UST Measure Blue Ground Red (UST B)


Test 3: Column

GST Guard Red Blue (GAR RB)


Multiple-Module Circuit Breakers


Multiple I-Module Test Procedure

• Test each interrupter chamber (normally by UST)• Test each column (normally by GST Guard)



Multiple T- and Y-Module Procedure

• 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


Complex Live-Tank Circuit Breakers

BBC Type DLFTest Energize Ground Guard UST

1 B C,F - A2 B A,F - C3 D E,F - C4 D C,F - E5 F B,D - -

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


Analysis


- manufacturer’s nameplate and specification- similar insulation specimens

normally tests with similar current and capacitance- similar breakers- Doble’s typical results and database

• Later tests compared with initial test valueQuestionable results in later tests- manufacturer’s specification- Doble’s typical results and database


Analysis



• Later tests compared with initial test value (% diff.)- Good less than 5 %- deteriorated from 5 % to less than 10 %- investigate 10 % and higher


Analysis: Interrupter Chamber

Interrupter chamber with grading capacitor• Dominated by grading capacitor

also includes interrupter chamber and any resistor switch chamber

• Power factor generally less than 1.0 %Diagnostics• High power factor

degraded grading capacitor, interrupter chamber, resistor switch chambertest separately grading capacitor, interrupter chamber and resistor switch chamber


Analysis: Interrupter Chamber

Interrupter chamber with no grading capacitor• Includes interrupter chamber, any resistor switch

chamber• Very low current, evaluate losses• Losses generally 0.020 Watts or lessDiagnostics• High losses

degraded interrupter chamber, resistor switch chambertest separately interrupter chamber, resistor switch chamber


Analysis: Column

Column Insulation• Very low current, evaluate losses• Losses generally 0.030 Watts or less• Very sensitive to external surface conditionsDiagnostics• High losses

- perhaps operate breaker and re-test- test individual column sections- check for leaks


C1 C2

S1


Test CapTest Ph Insul kV I (mA) Watts % PF (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

S1


Individual grading capacitor tests

Test % PFTest Ph Insul kV % PF Tip-Up

1 A C2 2 0.4210 0.42 0.00

2 B C2 2 0.46

3 C C2 2 1.2010 0.97 - 0.23

10 0.46 0.00

C-phase C2 grading capacitor was replaced

AEG Type S2 – 420, 420 kV


Case 7: Contaminated SF6 Gas

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 Purity99.7 %99.5 %91.7 %

Siemens 3AT5, 500 kV

Columns 5 and 6

Columns 1 and 2Columns 3 and 4


Case 7: 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

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