INSULATION COORDINATION AC HIGH VOLTAGE CIRCUIT …

INSULATIONINSULATIONCOORDINATIONCOORDINATION

AC HIGH VOLTAGEAC HIGH VOLTAGECIRCUIT BREAKERSCIRCUIT BREAKERS

STEPHEN R. LAMBERTSTEPHEN R. LAMBERTSHAWNEE POWER CONSULTING, LLCSHAWNEE POWER CONSULTING, LLC

1. Preinsertion Resistor

2. Grading Capacitor

3. Interrupter

4. Support Column

INSULATION PATHSINSULATION PATHS

PHASE TO GROUND

ACROSS THE OPEN BREAKER

PHASE TO PHASE

1. Preinsertion Resistor

2. Grading Capacitor

3. Interrupter

4. Support Column

VOLTAGE STRESSESVOLTAGE STRESSES

60 Hz

SWITCHING SURGES

LIGHTNING SURGES

60 Hz Overvoltages60 Hz Overvoltages

UNGROUNDED SYSTEMS – 1.73 PUWITH FAULTS

ACROSS OPEN BREAKER – 2.2 PU

SWITCHING SURGE SWITCHING SURGE OVERVOLTAGESOVERVOLTAGES

NO SURGE CONTROLENERGIZING – 3.0 PURECLOSING (trapped charge) – 4.0 PU

WITH PREINSERTION RESISTORS – 2.2 PU

SURGE ARRESTERS LIMITING – 1.9 PU

2.90 PU Phase to Ground Switching Surge345 kV System

-1000

-800

-600

-400

-200

0

200

400

600

800

20 30 40 50 60 70 80 90 100 110 120

Time (ms)

kV

Application of 276 kV Surge Arrester1.83 PU

-600

-400

-200

0

200

400

600

20 30 40 50 60 70 80 90 100 110 120

Time (ms)

kV

-1000

-800

-600

-400

-200

0

200

400

600

800

20 30 40 50 60 70 80 90 100 110 120

Time (ms)

kV

Application of 276 kV Surge Arrester1.83 PU

LIGHTNINGLIGHTNINGFLASHFLASH

CHARACTERISTICSCHARACTERISTICS

+++++++++ ++++++++++++++++ +++++++

++---------------------- -------------------- ++

-- ++-- ++

Neg Flash Pos Flash

FLASH STATISTICSFLASH STATISTICS55% OF FLASHES HAVE MORE THAN ONE STROKE

90% OF FLASHES HAVE LESS THAN NINE STROKES

MEAN NUMBER OF STROKES/FLASH -THREE

80-90% OF STROKES ARE NEGATIVE

LIGHTNINGLIGHTNING

CHARACTERIZED BY

CURRENT MAGNITUDE

STROKE RISE TIME

KERAUNIC LEVEL OR FLASHES/km2

STROKE MAGNITUDESSTROKE MAGNITUDES

0.01

0.1

1

10

100

0 50 100 150 200 250

Stroke Current kA

Prob

. of E

xcee

ding

Abs

ciss

a First Stroke

STROKE MAGNITUDESSTROKE MAGNITUDES

0.01

0.1

1

10

100

0 50 100 150 200 250

Stroke Current kA

Prob

. of E

xcee

ding

Abs

ciss

a

First StrokeSubsequent Strokes

TYPICAL FIRST STROKETYPICAL FIRST STROKE

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0 5 10 15 20 25 30 35 40

μs

pu c

urre

nt

First Stroke

SUBSEQUENT STROKESSUBSEQUENT STROKES

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0 5 10 15 20 25 30 35 40

μs

pu c

urre

nt

First Stroke

Subsequent Strokes

1.2 x 50 IMPULSE SHAPE1.2 x 50 IMPULSE SHAPE

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0 5 10 15 20 25 30 35 40

μs

pu c

urre

nt

First Stroke

Subsequent Strokes

1.2 x 50 wave

GROUND FLASH DENSITYGROUND FLASH DENSITY

GROUND FLASH DENSITYGROUND FLASH DENSITY

HOW DOES LIGHTNING GET HOW DOES LIGHTNING GET INTO THE SYSTEM?INTO THE SYSTEM?

SHIELDING FAILURES

BACKFLASHOVERS

INDUCED

BACK FLASHOVERBACK FLASHOVER

`

Zsw

Zsw

Is

Ztwr

Ztfr

Vph

Vtwr

SHIELDING FAILURESHIELDING FAILUREZph 400 Ω

Is = 10 kA

Vph = ? `

Zsw

Zsw

Is

Ztwr

Vph

Vtwr

`

Zph

`

Zph

SHIELDING FAILURESHIELDING FAILUREZph 400 Ω

Is = 10 kA

Vph = 2 MV`

Zsw

Zsw

Is

Ztwr

Vph

Vtwr

`

Zph

`

Zph

EXAMPLEEXAMPLE

TLine TLine

SHIELDING FAILURESHIELDING FAILUREPHASE TO GROUND SURGEPHASE TO GROUND SURGE

@ OPEN BREAKER@ OPEN BREAKER

-1000

-500

0

500

1000

1500

2000

2500

3000

3500

5 7 9 11 13 15 17 19

Time (μs)

kV

INSULATION CAPABILITYINSULATION CAPABILITY& TESTING& TESTING

EARLY 1900’s

60 Hz TESTING ONLY

TEST LEVEL:2.25 x RATED VOLTAGE + 2000 V

1 MINUTE DRY – 10 SECONDS WET

POWER FREQUENCY TEST POWER FREQUENCY TEST LEVELSLEVELS

-960800

-860550

-555362

350425245

315365170

275310145

230260123

14016072.5

758038

506025.8

455015.5

10 Second Wet(kV, rms)

1 Minute Dry(kV, rms)

Rated MaximumVoltage (kV, rms)

Power Frequency Test

CONTACTS OPENCONTACTS OPEN

CONTACTS CLOSEDCONTACTS CLOSED

RATIO TEST VOLTGE TO RATEDRATIO TEST VOLTGE TO RATEDMAXIMUM VOLTAGEMAXIMUM VOLTAGE

2.08960800

2.71860550

2.66555362

3.00425245

3.72365170

3.70310145

3.66260123

3.8216072.5

3.658038

4.036025.8

5.595015.5

In pu of Rated L-G Voltage

1 Minute Dry

(kV, rms)

Rated Maximum

Voltage (kV, rms)

Power Frequency Test

MINIMUM CREEPAGE DIST.MINIMUM CREEPAGE DIST.CONTAMINATION ISSUES

LIGHT CONTAMINATION

MINIMUM CREEP AT 27.7 mm/kVrms, p-g

SALT FOG, INDUSTRIAL CONTAMINATION MAY NEED MORE CREEP

CREEPAGE REQUIREMENTSCREEPAGE REQUIREMENTS

12900800

8890550

5850362

3960245

2750170

2340145

1990123

117072.5

61038

42025.8

25015.5

Minimum Creepage to Ground,(mm)

Rated Maximum Voltage (kV, rms)

LIGHTNING IMPULSE TESTLIGHTNING IMPULSE TESTINTRODUCED IN 1930’s

TEST LEVEL – 2 x LF TEST + 40 kV

1.5 x 40 μs WAVE SHAPE

NOW – 1.2 x 50 μs

FULL WAVE & 2 μs CHOPPED WAVE

10 % PROB. OF FLASHOVER OR LESS

LIGHTNING IMPUSE LIGHTNING IMPUSE WAVESHAPEWAVESHAPE

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60

Time μs

V

LIGHTNING IMPUSE TEST LEVELSLIGHTNING IMPUSE TEST LEVELS

26402050800

23201800550

16801300362

1160900245

968750170

838650145

710550123

45235072.5

25820038

19415025.8

14211015.5

Chopped Wave (2μs)Full WaveRated MaximumVoltage (kV, rms)

Lightning Impulse

TEST PROCEEDURETEST PROCEEDURECONTACTS OPEN – ALL OTHER TERMINALS GROUNDED

CONTACTS CLOSED – ALL OTHER PHASES GROUNDED

APPLY THREE IMPULSES (NEG AND POS)

IF ZERO FLASHOVERS – PASS

IF ONE FLASHOVER IN FIRST THREE, THEN 9 MORE TESTS WITH NO FLASHOVERS

RATIO OF FULL WAVE IMPULSE RATIO OF FULL WAVE IMPULSE TO RATED MAXIMUM VOLTAGETO RATED MAXIMUM VOLTAGE

3.1420508004.0118005504.4013003624.509002455.407501705.496501455.485501235.9135072.56.45200387.1215025.88.6911015.5

In pu of Rated L-G Crest Voltage

Full WaveRated MaximumVoltage (kV, rms)

Lightning Impulse

SWITCHING IMPULSE TESTINGSWITCHING IMPULSE TESTING

INCREASE IN SYSTEM VOLTAGE TO EHV LEVELS - 345 AND 500 kV

BEGUN IN EARLY 1960’S

TEST WAVESHAPE - 250 x 2500 μs

TEST PROCEDURETEST PROCEDUREPOSITIVE AND NEGATIVE POLARITIES

SAME 3 – 9 TEST SERIES

WET AND DRY TESTS REQUIRED

OPEN AND CLOSED TEST VALUES DIFFERENT

10 % PFO OR LESS

TEST LEVELSTEST LEVELS

15001425800

13001175550

900825362--245--170--145--123--72.5--38--25.8--15.5

Breaker Open(kV, cr)

Breaker Closed(kV, cr)

Rated MaximumVoltage (kV, rms)

Switching Impulse Terminal toTerminal

RATIO OF TEST LEVELS TO RATIO OF TEST LEVELS TO RATED MAXIMUM VOLTAGERATED MAXIMUM VOLTAGE

2.181425800

2.621175550

2.79825362

In pu of Rated L-G Crest Voltage

Breaker Closed(kV, cr)

Rated MaximumVoltage (kV, rms)

Switching Impulse Terminal toTerminal

2.90 PU Phase to Ground Switching Surge345 kV System

-1000

-800

-600

-400

-200

0

200

400

600

800

20 30 40 50 60 70 80 90 100 110 120

Time (ms)

kV

Application of 276 kV Surge Arrester1.83 PU

-600

-400

-200

0

200

400

600

20 30 40 50 60 70 80 90 100 110 120

Time (ms)

kV

LIGHTNING SURGE PROTECTIONLIGHTNING SURGE PROTECTIONUSE OF GAPUSE OF GAP

TLine TLine

LIGNTINING SURGE LIGNTINING SURGE PROTECTION PROTECTION -- GAPSGAPS

-4000

-3000

-2000

-1000

0

1000

2000

5 7 9 11 13 15 17 19

Time (μs)

kV

2 m Rod Gap

No Protection

APPLICATION OF ARRESTERAPPLICATION OF ARRESTERSEPARATION DISTANCESEPARATION DISTANCE

TLine TLine

APPLICATION OF ARRESTERAPPLICATION OF ARRESTERPHASE TO GROUND AT OPEN BREAKERPHASE TO GROUND AT OPEN BREAKER

-500

0

500

1000

1500

2000

5 7 9 11 13 15 17 19

Time μs

kV

80 m separation40 m0 m

APPLICATION OF ARRESTERAPPLICATION OF ARRESTERACROSS OPEN BREAKERACROSS OPEN BREAKER

0

500

1000

1500

2000

2500

5 7 9 11 13 15 17 19

Time μs

kV

80 m separation40 m0 m

EFFECT OF ALTITUDEEFFECT OF ALTITUDE

TESTED AT NTP (normal temperature and pressure)

REDUCTION IN EXTERNAL INSULATION WITH INCREASING ALTITUDE

ALTITUDE CORRECTION ALTITUDE CORRECTION FACTORFACTOR

H – ALTITUDE IN METERS

m – GAP FACTOR1 FOR POWER FREQUENCY, LIGHTNING AND PHASE TO PHASE SWITCHING SURGES0.9 FOR INSULATION ACROSS OPEN GAP0.75 FOR PHASE TO GROUND SWITCHING SURGES

)8150

( Hm

d ek−

=

ALTITUDE CORRECTIONALTITUDE CORRECTION

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

0 500 1000 1500 2000 2500 3000 3500 4000

Alltitude Above Sea Level, m

Alti

tude

Den

sity

Cor

rect

ion

Fact

or

Switching Surge to GroundLightning

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1

Deviation in Strength in Number of Sigmas

Prob

abili

ty o

f Pas

sing

Tes

t

3+33+915x2