determination of arrester energy handling capability ... · • new mov arrester blocks were surged...

Determination of Arrester EnergyHandling Capability

- Testing Investigation

Surge Protective Devices CommitteeSpring 2005 Meeting

Raymond C. Hill, PE

Georgia Institute of Technology © 2005


Introduction

• Conflicting opinions exist concerning the method of rating the energy handling capability of MOV arresters.

• The top contenders comprise the following methods:

• “Joule” – kJ / kV mcov

• “Coulomb” – charge transfer

• “I-squared-t” – action integral


Introduction

• A project proposal was made to NEETRAC by an SPDC officer and member of the NEETRAC Technical Advisors to investigate.

• In the fall of 2001, NEETRAC launched Phase I of a Baseline Research Project funded by the membership in order to investigate and provide input to the IEEE SPDC.


Introduction

• Phase I involved a test program utilizing one size of a single MOV arrester block and was completed at the end of 2002.

• Phase II was then proposed to investigate additional MOV arrester blocks with different aspect ratios.


Introduction

• In the fall of 2003, NEETRAC launched Phase II of the investigation.

• Phase II was a test program utilizing several sizes of a single MOV arrester block with different aspect ratios.

• NEETRAC has recently completed Phase II of the investigation.


Purpose & Scope – Phases I & II

• To investigate the energy handling capability of single MOV arrester blocks

• To determine which method(s) of energy rating will describe this parameter across the board providing an equal energy rating system for all concerned.


Purpose & Scope – Phases I & II

• Various sizes of blocks with different aspect ratios were tested in order to investigate the relationship of height, width, volume, and cross-sectional area to energy handling capability.

• Various impulse waveforms were used to investigate the relationship between waveshape and energy handling capability of the various sizes and aspect ratios of MOV arrester blocks.

• A total of more than 160 MOV blocks were surged during this investigation.


Test Procedure

• New MOV arrester blocks were surged (individually) to determine the single-surge-to-failure level using various current impulse waveforms.

• The surge current and voltage waveforms were digitized and recorded.

• Calculations were then made to determine the Joule, Coulomb, and I2t values of the surges just prior to and after destruction.


Test Procedure

• The three methods of energy rating were then analyzed and compared utilizing the various parameters of the MOV arrester blocks.

• A determination was then made as to which method was the most consistent and accurate.


Test ProcedureWaveforms, Generators, and Fixtures

• Standard Wave – 8 / 20 µs

• Long Tail Wave – 9 / 170 µs

• Triangle Wave1. 180 / 410 µs2. 165 / 370 µs



Impulse Current Waveshapes( Normalized to 1kA)

0100200300400500600700800900

10001100

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

Time (us)

Cur

rent

(A).

180/410 9/170 10/350 8/20



8 / 20 µs generator and SF6 pressure vessel



SF6 Pressure Vessel



Sample Fixture within SF6 Pressure Vessel



Long Tail and Triangle Wave Generator



Sample Holder for the Long Tail and Triangle Waves


Sample Sets for Phases I & II

Table 1

QuantityHeight

(inches)Height (mm)

Width (inches)

Width (mm)

Aspect Ratio (width/height)

Volume (mm3)

Cross-sectional

Area (cm2)

MCOV (kV)

approx.Sample

Designation50 0.082 2.1 1.408 35.8 17.2 2092 10.065 0.15 A1 - A5050 0.1975 5.0 1.410 35.8 7.1 5053 10.074 0.66 B1 - B5050 0.597 15.2 1.278 32.5 2.1 12549 8.276 1.55 C1 - C5050 0.855 21.7 1.2735 32.3 1.5 17846 8.218 2.2 D1 - D5050 0.599 15.2 1.641 41.7 2.7 20760 13.645 1.55 E1 - E5050 0.884 22.5 1.648 41.9 1.9 30899 13.789 2.3 F1 - F5050 0.608 15.4 3.064 77.8 5.0 73461 47.539 1.55 G1 - G5050 0.921 23.4 3.066 77.9 3.3 111425 47.661 2.4 H1 - H50

100+ 0.914 23.2 1.312 33.3 1.4 20248 8.722 2.4 A - ZZZZ

MOV blocks were provided byCooper Power Systems and Hubbell / Ohio Brass


Sample Sets for Phases I & II

A

B

C

D

E

F

G

HComplete Set


Failure Criteria

• Individual samples were surged only once each until the failure level was achieved for that block design.

• Several data sets above the failure level and below (withstand) were then acquired. The “one block - one surge only” protocol was maintained throughout.

• A failure was defined as any physical damage to the block.


Failure Criteria

• A flashover across the edge of the block was not considered a failure.

• Examples of failures:


Phase I ResultsTable 2

Waveshape Sample

Current Front Time (us)

Current Tail

Time (us)

Duration or Time-

to-Failure

Capacitor Charge Voltage

(kV)

Peak Current

(kA)I*t

(Coulombs)

(I**2)*t (Ampere-squared-seconds)

V*I*t (kJ)

Block Withstand /

Fail CommentsCC 185 406 518.5 15.72 5.26 1.709 7057 14.933 w/stand Epoxy collar bubbled

DD 175 414 518.5 15.62 5.84 1.913 8809 15.073 failVery small hole and crack at edge

EE 182 407 518.5 15.53 4.88 1.599 6170 14.324 w/stand Epoxy collar bubbledFF 185 410 518.5 15.66 4.92 1.619 6300 14.564 w/stand Epoxy collar bubbledGG 179 396 518.5 15.76 5.08 1.613 6474 14.277 w/stand Epoxy collar bubbled

MMM 172 402 510 15.28 5.00 1.628 6373 14.040 w/standNNN 180 370 475 15.27 5.60 1.642 6987 14.105 w/stand

SSS 164 388 503 16.02 5.70 1.784 7923 15.497 failChannel part way down the edge

TTT 176 406 515 16.01 6.10 1.994 9582 15.570 w/standUUU 162 392 496.5 16.02 6.20 1.947 9464 15.474 w/standVVV 166 406 520 16.10 5.50 1.774 7534 15.521 w/stand

WWW 166 406 517.5 16.15 5.50 1.793 7710 15.649 w/standXXX 167 406 520 16.21 5.40 1.749 7240 15.800 w/standYYY 175 412 530.5 16.33 5.20 1.713 6857 15.925 w/standZZZ 158 372 474.5 16.03 5.80 1.756 8039 15.377 w/stand

AAAA 159 390 503.5 16.01 5.40 1.659 6794 15.083 w/standBBBB 161 380 486.2 16.52 5.80 1.752 7806 16.183 w/stand

CCCC 172 n/app 278.5 17.00 6.40 1.284 6873 10.960 fail

Failed near edge; blew off portion of block; epoxy collar bubbled

DDDD 169 402 513.3 17.01 6.00 1.967 9290 17.508 w/stand

EEEE 178 n/app 217.7 17.01 6.10 0.883 4281 7.849 failBlew off chip on the edge

Triangle (180/410)



Waveshape Sample


Current Tail

Time (us)

Duration or Time-

to-Failure


(kV)

Peak Current

(kA)I*t

(Coulombs)


V*I*t (kJ)

Block Withstand /

Fail Comments

HH 9.28 172 950 14.6 4.24 0.994 2222 7.663 failChannel halfway down the edge

II 9.50 160 950 14.3 4.00 0.943 1985 7.311 failChannel halfway down the edge

JJ 9.23 162 950 14.1 3.94 0.928 1922 7.105 fail

Channel halfway down the edge, then blew off portion of the block

KK 9.44 166 950 13.6 3.64 0.866 1663 6.577 w/standLL 9.13 172 950 13.6 3.48 0.850 1557 6.606 w/stand

MM 9.10 166 950 13.7 3.66 0.872 1678 6.719 w/standNN 9.87 174 950 13.8 3.28 0.810 1394 6.688 w/stand

OO 9.25 170 950 13.8 3.70 0.896 1751 6.853 failChannel halfway down the edge

PP 8.92 164 950 13.7 3.80 0.900 1795 6.735 w/standQQ 9.12 166 950 13.7 3.70 0.886 1727 6.722 w/stand

PPP 7.84 166 896 14.5 4.10 1.104 2330 8.793 failPuncture near center; split block

QQQ 8.04 170 896 14.0 4.10 1.077 2279 8.085 w/standFFFF 7.50 170 897 14.5 4.10 1.038 2231 8.172 w/stand

GGGG 8.00 160 897 15.0 4.70 1.151 2796 8.748 fail

Puncture 5 mm from edge; blew off portion of the block

HHHH 7.87 166 897 15.1 4.70 1.160 2762 9.015 failChannel part way down the edge

Long Tail (9/170)



Waveshape Sample


Current Tail

Time (us)

Duration or Time-

to-Failure


(kV)

Peak Current

(kA)I*t

(Coulombs)


V*I*t (kJ)

Block Withstand /

Fail Comments

ZZ 8.14 17.2 39.1 90 101 1.750 116,160 32.058 fail

Surged under SF6; failed during current reversal; failed near edge; blew off portion of the block; left a tree-like pattern on the side

XX 8.66 18.6 46.5 85 88 1.696 96,561 29.289 w/stand Surged under SF6CCC 9.00 18.0 44.7 92 97 1.822 114,037 32.441 w/stand Surged under SF6

EEE 8.50 18.4 19.2 92 99 1.338 105,537 25.430 fail

Surged under SF6; failed along the edge burning a tree-like pattern on the side

FFF 8.50 18.4 45.3 94 99 1.895 121,780 33.994 w/stand Surged under SF6

Standard (8/20)


Phase I Results

• A first review of the impulse data values for Coulombs, I2t, and Joules reveals no obvious correlation among the three different waveforms.

• However, when the “total duration” of the surge or “time-to-failure” is taken into account, a correlation appears. This is shown graphically in the following figures.


Phase I Results

Arrester Block Single-Shot Energy CapabilityKilojoule Method

y = 21.284e-0.0011x

1

10

100

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration or Time-to-Failure

Kilo

joul

es


Phase I Results

Arrester Block Single-Shot Energy CapabilityAction Integral (Ampere-Squared-Seconds) Method

y = 45682e-0.0034x

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration or Time-to-Failure (us)

Am

pere

-Squ

ared

-Sec

onds


Phase I Results

Arrester Block Single-Shot Energy CapabilityCoulomb Method

y = 1.5224e-0.0004x

0.1

1

10

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration or Time-to-Failure (us)

Cou

lom

bs


Phase I Results

• When the pass/fail data for all three waveforms is plotted versus total pulse duration or time-to-failurefor each energy method, a definitive border appears among the pass/fail data.

• In general, any current surge with an energy content and duration which falls below this border will not cause an MOV block failure for the design tested.

• This border or trend line can be defined as shown in the following equation:


Phase I Results

β e -mt

• “β” represents the y-intercept, which is themaximum energy achieved with an infinitesimally small pulse width.

• The coefficient “m” represents the slopeof the line and “t” is time (pulse width).

• With this method, the borderline of failurecan be described by defining these two coefficients.


Phase I Results

• This equation is waveform independent fordurations less than 1000 microseconds.

• Each energy rating method would require aunique set of coefficients.

• At this point, the equation only applies toone MOV block size.

• This equation fits the Coulomb or “chargetransfer” method better than the others which exhibit more of an upturn for times less than 200 microseconds. Obviously, further investigation is required.


Phase I ResultsAdditional Observations Worth Noting

• The slope of the Coulomb equation was found to be small, such that, when considering the data scatter (and with further investigation), one might conclude that a single Coulomb value could be assigned to the MOV arrester block design utilized in this project in lieu of an equation.

• With the exception of Sample PPP, all of the block puncture locations were along the edge or within 5 mm of the edge.


Phase II Results - Tabulated

Table 5

Waveshape Sample


Current Tail

Time (us)

Duration or Until

Failure or Flashover


(kV)

Peak Current

(kA)I*t

(Coulombs)


V*I*t (kJ)

Block Withstand

/ Fail / Flashover

(f / o) Comments

MCOV (kV)

approx.

Aspect Ratio

(width/height)

Width (mm)

Height (mm)

B49 10.40 20.5 20.9 50 56 0.839 38,125 3.11 f / o 20 psig SF6 0.66 7.1 35.8 5.0C10 10.96 22.7 54 90 84 2.298 126,993 29.06 w/stand 20 psig SF6 1.55 32.5C11 10.72 23.1 49.7 90 85 2.273 132,034 29.55 f / o 20 psig SF6 1.55 32.5C4 10.19 21.0 78.8 75 77 2.188 101,570 23.35 w/stand 25 psig SF6 1.55 32.5C9 10.94 22.7 49.4 90 85.5 2.262 130,721 29.19 f / o 20 psig SF6 1.55 32.5

D48 9.69 22.2 56.9 90 80 2.002 103,721 34.51 w/stand 15 psig SF6 2.2 32.3D49 10.25 22.1 56.2 90 81.5 1.99 105,197 34.6 w/stand 15 psig SF6 2.2 32.3D50 10.34 21.8 55.4 90 81 1.983 104,632 34.35 w/stand 25 psig SF6 2.2 32.3E2 11.25 23.4 45.3 90 87 2.231 137,446 23.87 f / o 20 psig SF6 1.55 41.7E3 10.50 22.0 46.3 85 86 2.244 134,085 23.18 f / o 20 psig SF6 1.55 41.7E4 10.96 23.1 57.9 80 77 2.238 115,016 21.55 f / o 20 psig SF6 1.55 41.7E5 9.69 20.3 41.2 75 79 1.828 101,100 18.17 f / o 20 psig SF6 1.55 41.7UU 9.00 21.4 51.7 93 92 2.039 121,818 36.88 w/stand 25 psig SF6 2.4 1.4 33.3 23.2

8/20

2.1 15.2

1.5 21.7

2.7 15.2


Phase II Results – TabulatedTable 6

Waveshape Sample


Current Tail

Time (us)

Duration or Until



(kV)

Peak Current

(kA)I*t

(Coulombs)


V*I*t (kJ)

Block Withstand

/ Fail / Flashover

(f / o) Comments

MCOV (kV)

approx.

Aspect Ratio

(width/height)

Width (mm)

Height (mm)

C13 8.25 157 900 14.7 5.00 1.103 2,923 6.51 fail 1.55 32.5C14 8.75 154 900 14.7 5.00 1.102 2,913 6.52 w/stand 1.55 32.5C15 8.75 156 900 14.8 5.10 1.122 3,020 6.67 fail 1.55 32.5C16 8.50 157 900 14.75 5.00 1.107 2,924 6.58 fail 1.55 32.5C17 8.50 156 900 14.7 5.00 1.102 2,904 6.54 fail 1.55 32.5C18 8.88 156 900 14.6 4.90 1.078 2,762 6.34 w/stand 1.55 32.5C19 8.50 155 900 14.7 5.10 1.121 3,006 6.62 fail 1.55 32.5C20 8.13 156 900 14.6 4.90 1.093 2,843 6.37 fail 1.55 32.5C21 8.38 158 900 14.55 4.90 1.093 2,793 6.49 fail 1.55 32.5C22 8.63 154 900 14.5 5.35 1.182 3,308 7.12 fail 1.55 32.5C12 8.38 157 900 14.0 4.60 1.015 2,497 n/av w/stand no voltage trace 1.55 32.5C24 8.50 172 853 13.8 5.10 1.197 3,289 7.10 fail 1.55 32.5C25 9.50 179 853 13.0 4.70 1.105 2,787 6.47 fail 1.55 32.5C26 9.38 177 853 12.5 4.35 1.045 2,440 6.04 fail 1.55 32.5C27 9.75 180 853 12.0 4.00 0.977 2,103 5.58 w/stand 1.55 32.5C28 9.00 178 853 12.0 3.95 0.971 2,082 5.56 fail 1.55 32.5C29 8.88 177 853 11.7 3.85 0.946 1,959 5.37 w/stand 1.55 32.5C30 9.38 180 853 11.7 3.85 0.937 1,921 5.29 fail 1.55 32.5C31 8.88 180 853 11.5 3.65 0.905 1,781 5.11 w/stand 1.55 32.5C32 9.38 183 853 11.5 3.68 0.910 1,795 5.10 fail 1.55 32.5C33 9.25 184 854 11.0 3.37 0.839 1,518 4.67 fail 1.55 32.5C34 9.38 193 854 10.5 3.08 0.776 1,283 4.27 w/stand 1.55 32.5C35 9.38 194 854 10.5 3.15 0.789 1,329 4.35 w/stand 1.55 32.5B3 9.13 164 853 10.0 5.55 1.236 3,721 2.23 fail 0.66 35.8B4 9.50 171 853 8.0 4.30 0.969 2,249 1.61 w/stand 0.66 35.8B5 9.00 175 853 9.0 4.70 1.088 2,835 n/av fail 0.66 35.8B6 9.63 168 853 9.0 4.95 1.104 2,958 1.86 fail 0.66 35.8B7 8.88 168 853 8.5 4.55 1.026 2,540 1.77 fail 0.66 35.8B8 9.00 169 853 8.0 4.30 0.958 2,218 1.60 fail 0.66 35.8B9 9.13 172 854 7.5 3.90 0.878 1,871 1.47 w/stand 0.66 35.8

B10 9.13 167 854 7.5 3.95 0.888 1,922 1.50 w/stand 0.66 35.8B11 9.13 169 854 8.0 4.25 0.950 2,205 1.61 w/stand 0.66 35.8E6 9.13 174 853 14.6 6.00 1.396 4,502 7.68 w/stand gen. can't fail 1.55 41.7E7 9.00 172 853 14.9 6.20 1.449 4,839 7.92 w/stand gen. can't fail 1.55 41.7

9/170

2.1 15.2

7.1 5.0

2.7 15.2


Phase II Results - Tabulated

Table 7

Waveshape Sample


Current Tail

Time (us)

Duration or Until



(kV)

Peak Current

(kA)I*t

(Coulombs)


V*I*t (kJ)

Block Withstand

/ Fail / Flashover

(f / o) Comments

MCOV (kV)

approx.

Aspect Ratio

(width/height)

Width (mm)

Height (mm)

B14 215 460 716 9.0 2.75 1.042 2,141 2.14 f / o 0.66 35.8

B15 215 n/av n/av 9.0 2.75 n/av n/av n/av f / o

can't determine when f/o ocurred

0.66 35.8

C36 165 370 468 10.0 1.56 0.459 569 2.76 w/stand gen. can't fail 1.55 32.5C37 165 370 467 11.0 1.95 0.566 864 3.46 w/stand gen. can't fail 1.55 32.5C38 165 370 463 12.0 2.30 0.658 1,178 4.13 w/stand gen. can't fail 1.55 32.5C39 165 370 465 13.0 2.60 0.747 1,505 4.82 w/stand gen. can't fail 1.55 32.5C40 165 370 456 14.0 3.00 0.845 1,963 5.54 w/stand gen. can't fail 1.55 32.5C41 165 370 463 15.0 3.25 0.936 2,371 6.22 w/stand gen. can't fail 1.55 32.5C42 165 370 457 16.0 3.70 1.038 2,957 7.07 w/stand gen. can't fail 1.55 32.5

Triangle Wave

7.1 5.0

2.1 15.2


Phase I & II Results – with AE I Borderline Equation

Arrester Block Single-Shot Energy CapabilityKilojoule Method by Aspect Ratio and Pulse Duration

1

10

100

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration

Kilo

joul

es

1.4 w/s1.4 AEI w/s1.4 AEI fail1.5 w/s2.1 w/s2.1a w/s2.1b w/s2.1a fail2.1b fail2.7 w/s2.7a w/s7.1 w/s7.1 fail2.1c w/s7.1a w/sAEI Eq


Phase I & II Results with AE I Borderline Equation

Arrester Block Single-Shot Energy CapabilityAction Intergal Method by Aspect Ratio and Pulse Duration

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration

Am

pere

-squ

ared

-sec

onds

1.4 w/s1.4 AEI w/s1.4 AEI fail1.5 w/s2.1 w/s2.1a w/s2.1b w/s2.1a fail2.1b fail2.7 w/s2.7a w/s7.1 w/s7.1 fail2.1c w/s7.1a w/sI sqrt t AEI


Phase I & II Results with AE I Borderline Equation

Arrester Block Single-Shot Energy CapabilityCoulomb Method by Aspect Ratio and Pulse Duration

0

1

10

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration

Cou

lom

bs

1.4 w/s1.4 AEI w/s1.4 AEI fail1.5 w/s2.1 w/s2.1a w/s2.1b w/s2.1a fail2.1b fail2.7 w/s2.7a w/s7.1 w/s7.1 fail2.1c w/s7.1a w/sAE1 Eq


Phase II Results

• As can be seen, the borderline equation from Phase I requires adjusting in order to take into account the variance caused by the different MOV block sizes.

• Many different aspects of MOV block size were compared with the three energy rating methods.

• The correlations of predominant interest are the following:


Phase I & II ResultsArrester Energy in Kilojoules per Unit Diameter

0.01

0.10

1.00

10.00

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

Kilo

joul

es /

mm

dia

met

er

w/s AE Ifail AE Iw/s AE IIfail AE IIAEI Eq


Phase I & II Results

Arrester Energy in Kilojoules per kV of MCOV

1

10

100

0 100 200 300 400 500 600 700 800 900 1000

Duration (us)

kilo

joul

es p

er k

V o

f M

CO

V .

2.1 w/s

2.1 fail

7.1 w/s

7.1 fail

2.1c w/s

7.1a w/s

1.4 AE I w/s

1.4 AE I fail



Arrester Energy in Kilojoules per kV of MCOV per Unit Diameter

0.01

0.10

1.00

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration

kJ /

kVm

cov

/ mm

w/s AE Ifail AE Iw/s AE IIfail AE II



Arrester Energy in "I squared t" per Unit Diameter

10

100

1000

10000

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

Am

pere

-squ

ared

seco

nds /

mm

dia

met

er

w/s AE Ifail AE Iw/s AE IIfail AE III sqr t AEI



Arrester Energy in "I - squared - t" per Kilovolt of MCOV

100

1000

10000

100000

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

Am

pere

-squ

ared

seco

nds /

kV

of M

CO

V.




Arrester Energy in Coulombs per Kilovolt of MCOV

0.1

1.0

10.0

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

C /

kVm

cov




Arreser Energy in Coulombs per Unit Diameter

0.01

0.10

1.00

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

Cou

lom

bs /

mm

dia

met

er

w/s AE Iw/s AE IIfail AE Ifail AE IIAE I BorderlineAE I & AE II BorderlineThreshold



Arrester Energy in Coulombs per Unit Cross-sectional Area

0.01

0.10

1.00

0 100 200 300 400 500 600 700 800 900 1000

Pulse Duration (us)

Cou

lom

bs p

er sq

uare

cm

w/s AE Ifail AE Iw/s AE IIfail AE IIAE I BorderlineAE I & AE II BorderlineThreshold



Arrester Block Single-Shot Energy CapabilityCoulomb Method by Cross-sectional Area

0.1

1.0

10.0

0 5 10 15 20 25 30 35 40 45

Cross-sectional Area (square-cm)

Cou

lom

bs

AE I WithstandAE I FailAE II WithstandAE II Fail


Discussion / Conclusions

• The kilojoule per unit diameter data exhibits the most scatter of the three methods, with the most scatter occurring at the longer durations.

• The I2t per unit diameter data exhibits less scatter than the kilojoule method.

• The Coulombs per unit diameter and per unit cross-sectional area data also exhibit less scatter than the kilojoule method. (Converting the diameter to cross-sectional area allows for “square” MOV blocks.)


Discussion / Conclusions

• When inspecting the Coulombs per unit cross-sectional area graph, one could conceivably rate these arrester blocks at 0.09 or 0.1 Coulomb per square centimeter.

• A flat rating such as this would then be MOV “recipe” dependent along with any other presently unknown physical or dimensional limits. It is understood that two manufacturers provided samples, which could cause some scattering of the data due to different recipes.

• Any rating from this investigation is still limited to total pulse durations less than 1000 microseconds.


Future Work

• It is understood that further investigation is required before any solid conclusions can be reached. More data sets are needed.

• This data is presented to the IEEE Surge Protective Devices Committee as a challenge to industry leaders and other laboratories to help investigate further the possibilities presented here in order to obtain a more consistent method of rating arrester energy capability across the board for all concerned.

determination of arrester energy handling capability ... · • new mov arrester blocks were surged...

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