validating surge test

8/8/2019 Validating Surge Test

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Validating Surge Test Sta

High-Energy Tests a

Charles Fenimore, Member, IEEE aNational Institute of S

Gaithersburgf.martzlo
mailto:[email protected]:[email protected]


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IEEE TRANSACTIONS ON I

Validating Surge TExperience: Hig

Varistor PC h a r l e s F e n i m o r e , Member, IE E E,

Abstract-New, high-energy surge tests are emerging in IE


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FENIMORE AND MARTZLOFF: VALIDATING SURGE TEST STA

surge test requirement based on the scenario of currenlimiting fuses clearing a fault at the end of a cable, wherthe energy trapped in the system inductance causes large transient at the time the fuse interrupts the curren[31. That scenario was first described and quantified bMeissen [4] and incorporated in Ge rma n Standard V D0160 [5].The new C62.41 Recommended Practice proposeamong other waveforms, a high-energy stress defined ban open-circuit voltage and a source impedance at thre"system exposure" levels. Fo r the "low exposure" level, nhigh-energy stress is proposed ; for the "m edium exposure


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1236 IEEE TRANSACTIONS ON

TABLE IPREDICTED UMBERF HIGH-ENERGYURGESHAT A VARISTOCANSURVIVES A FUNCTIONOF SIZE ND CLAMPINGVOLTAGE OLERANCE

VaristorClampingSize Voltage VDE 0160 C62.41 C62.41mm Tolerance Class 2 High Medium

nonenonenonenonenone1none

none1813208

803000> lo

5008000"indefinite"20 000


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duration allowed by C62.41 is 2000 ps. The decay timewhich are expressed as full width at half maximu(FWHM) for these two waveforms are designated asand t,, respectively. Th e effective source impe danc edefined in C62.41 as the ratio of the peak open-circvoltage Vp to the peak short-circuit current I,. Its valZ = %/Ip has the dimension of an impedance.Because the time constants are widely separated, tdetermination of the circuit component values from tvalues of t,, t,, Z, and Vp can be simplified to produapproximate values. The characteristic decay values Aand A- ar e given by


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IEEE TRANSACTIONS O N

( L E A DINDUCTANCE1

Fig. 3. Equivalent circuit of a varistor (Source: [14]).

L of the complete equivalent circuit can be neglecte


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Typical manufa cturer specifications [I21 include a joulrating for maximum single pulses; however, industry stanards (Section 6, IEEE Standard on Varistor Test Specijictions [131) raise some questions on the application of suca simp le criterion.Th e cumulative energy levels for the thre e varistor siz(each at three tolerance levels) were computed with thmodel for the C62.41 and VDE 0160 stress levels. Thresults are shown in Table 11, together with the typicasingle-pulse joule rating published for these sizes. B


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IEEE TRANSACTIONS ON

VARISTOR

DIA Toler-mm ance

TMODELINGESULTS ERSUS EVDE 0160= 10011300~s IE2.3 x 220 x 1.4; 6000 YF;

250-V varistor


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Fraqois D. Martzloff (F'83) was born in Francwhere he completed his undergraduate traininand came to the United States in the 1950'scontinue his graduate studies.

In 1985, he joined the staff of the NationBureau of Standards (NBS, now NIST) to epand NBS activities in the field of conductelectromagnetic interference with more receemphasis on power quality and surge protectiissues. Prior to joining NBS, his long career General Electric included high-voltage fuses a

validating surge test

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