Reprinted, with permission, from 

Proceedings, 3rd International Symposium on Electromagnetic Compatibility, Rotterdam, 1979 

Significance:

Part 2 – Development of standards – Reality checks

Progress report to the European EMC community on the development of what became IEEE Std 587.

Explains the proposition that a Ring Wave should be added to the traditional unidirectional impulses 

NOTE: A parallel paper was presented to the 1979 IEEE PES community at the Summer Power Meeting

under the title “The Development of a Guideline on Surge Voltages in Low-Voltage AC Power Circuits”.

Filename: Guideline EMC
A GUIDELINE ON SURGE VOLTAGES IN AC POWER 

CIRCUITS RATED UP TO 600 V 

F.D. ?Aa:tz!cff 

General Electric Company 

Corporate Research and Development 

Schenectady, New York 12345, U.S.A. 

Summary 

Surge voltages occurring in ac power circuits can be 

the cause of misoperation or product failure for residential as well as industrial systems. The problem has received 

increased attention in recent years because miniaturized 

solid state devices are more sensitive to voltage surges 

(spikes and transients) than were their predecessors. 

Although surge voltage amplitudes and their frequexcy =f eccgrrence on unprotected circnits =re we!! 

known, their waveshapes and energy content are less well 

known. Qn the his of measurements; statltlc~: and 

theoretical considerations, a practical guideline for outlining the environment for use in predicting extreme 

waveshapes and energy content can nevertheless be established. The Surge Protective Device Committee of the 

Institute of Electrical and Electronics Engineers has been 

developing such a guideline, the essential elements of 

which are presented in this paper. 

Surge voltages [ 11 occurring in ac power circuits 

rated up to 600 V can be represented by various waveshapes 

in an attempt to duplicate actual surge voltages. Two 

major types of surges reflecting differences in the environment are described to represent the situation realistically. 

Systems located inside a building and separated from 

the overhead lines by some line impedance experience 

surge voltages of waveshapes and energy levels that differ 

from those of the outdoor environment. Outside systems 

exposed to direct lightning strikes or lightning-induced 

surges--typically overhead lines--experience levels implied L.. Wrrr ---->--A- I-- ------I ---- -aa-- TI.:- -,,:A-l:-- uy lccc DLalluaI UD IVI JCLUIIUaL y a1 ~CJLSLJ. LlUJ 6YIUFllllr 

addresses particularly the hazards to these two types of 

-..- rqi J,JLCIIIJ LL J. 

Scope 

The guideline presented here primarily addresses ac 

power circuits with rated voltages up to 600 V, although some of the conclusions offered could apply to higher 

voltages and also to some dc power systems. Other 

standards have been established, such as IEEE 472, Guide 

for %Surge Withstand Capability (SWC) Tests, intended for 

the special case of high-voltage substation environments, 

and IEEE 28, Standard for Surge Arresters for ac Power 

Circuits, covering primarily the utilities environment. The 

guideline presented here intends to complement, not 

conflict with, existing standards, and to present a practical 

proposal for the selection of voltage and current tests to be 

applied in evaluating the surge withstand capability of 

equipment connected to these power circuits, primarily in 

residential and light industrial applications. 

Some guidance is also presented on how to proceed 

from the environment description to the selection of 

"standard" test waves. 

The surge voltages [I I considered in this guideline & rhc* exceeding ?we pr unit (or twice the peak 

operating voltage) and having durations ranging iro

fraction of a microsecond to a millisecond. Overvolt

of less than two per unit are not covered here, nor 

transients of longer duration resulting from power eq

ment operation and failure modes. Because these 

amplitude and long-duration surges are generally 

amenable to suppression by conventional surge protec

devices, they require different protection techniques. 

1. The Origin of Surge Voltages 

Surge voltages occurring in low-voltage ac po

circuits originate from two major sources: !oad switch

transients and direct or indirect lightning effects on 

power system. Load switching transients can be fur

divided into transients associated with (1) major po

system switching disturbances, such as capacitor b

switching; (2) minor switching near the point of inter

such as an appliance turnoff in a household or the turn

of other loads in an individual system; (3) resona

circuits associated with switching devices, such as thy

tors; and (4) various system faults, such as short circ

and arcing faults. Measurements and calculations 

lightning effects have been made to yield data on w

levels can be produced, even if the exact mechanism of 

particular surge is unknown. The major mechanisms 

which lightning produces surge voltages are the followin

(a) A direct lightning strike to a primary cir

injects high currents into the primary circ

producing voltages by either flowing thro

ground resistance or flowing through the s

impedance of the primary conductors. 

(ti) A !igh:ning s:rike that misses the !he but h

nearby object sets up electromagnetic fi

*zhich can induce vo!?=pes on the conduc?or

the primary circuit. 

(c) The rapid collapse of voltage that occurs wh

primary arrester operates to limit the prim

voltage couples effectively through the cap

tance of the transformer and produces s

voltages in addition to those coupled into 

secondary circuit by normal transformer acti

(d) Lightning strikes the secondary circuits direc

Very high currents can be involved, excee

the capability of conventional devices. 

(e) Lightning ground current flow resulting f

nearby direct-to-ground discharges couples 

the common ground impedance paths of 

grounding network. 

Fast-acting protection devices, such as curr

limiting fuses and circuit breakers capable of clearin

beginning to part contacts in less than 2 ms, leave trap

inductive energy in the circuit upstream; upon collaps

the field, very high voltages are generated. 

Transient overvoltages [ I I associated with 

:-itching of pe~~er facoy coyrffction cq=citors haye 

frequencies than the high-frequency spikes with which 

dnmment is concerned; Their !eve!sj at !east in the ca
restrike-free switching operations, are generally less than 

twice normal voltage and are therefore not of substantial 

concern here, but should not be overlooked. 

On the other hand, switching operations involving r,.rh .; +h,,, ,.-I ., A h.. . LsJL, LnCJ, D"C1I ,,lux y. YUUCCU YJ -,,+,,+,.. 

CYr,racrY, a 0: 

mercury switches, can produce, through escalation, surge 

voltages of complex waveshapes and of amplitudes several *: -.-. ---- *-- -L-- *L- 8 L-- TLillllca gr cairr LII~II LIE IIUIIII~I SYSLCIII VUILI~C. I IIC 

severest case is generally found on the had side of the 

switch and involves only the device that is being switched. 

While this situation should certainly not be ignored, in such 

a case the prime responsibility for protection rests with the 

local user of the device in question. However, switching 

transients can also appear on the line side across devices 

connected to the line. The presence and source of 

transients may be unknown to the users of those devices. 

This potentially harmful situation occurs often enough to 

command attention. 

2. Occurrence and Voltage Levels in IJnprotected Clrcljltr. 

2.1 Rate of Occurrence Versus Voltage Level Tho ...- rat- .-.- nf nrrnwronrn ----..-..-- nf awooC --.--" vsrioe .-.--- nvnr W~AP -7-. ..A-- 

limits, depending on the particular system. Prediction of 

the rate for a particular system is always difficult and 

frequently impossible. Rate is related to the level of the 

surges; low-level surges are more prevalent than high-level 

surges [ 31. Data collected from many sources (Appendix I) 

have led to the plot shown in Figure 1. This prediction 

shows with certainty only a relative frequency of occurrence, while the absolute number of occurrences can be 

described only for an "average location." The "high 

exposure" and "low exposure" limits of the band are shown 

as a guide, not as absolute limits [21, to reflect both the 

location exposure (lightning activity in the area and the 

nature nf the system! and the expos~e to stvitching sllrges 

created by other loads. Such data are useful in that they 

describe the maximum levels likely to be encountered and 

-.:.... -..-^ ..-a:--*.. ^S &La ....LA ..* ^^^..""^^^^ ^* "..^,. slvs ~u~nls saun#rars YL uns ~ars ul u~cut~st~s ut ~ucln 

surges. Of equal importance is the observation that surges 

in the range of 1 to 2 kV are fairly common in residential 

circuits. 

SURGE CREST kV 

F~gure 1. Rate of Surge Occurrence vs Voltage Level 

From the relative values of Figure 1, two typical 

levels can be cited for practical applications. First, the 

expectation of a 3 kV transient occurrence on a 120 V 

circuit ranges from 0.01 to I per year at a given location - a number sufficiently high to justify the recommendation 

of a minimum 3 kV withstand capability. Second, the 

wiring flashover limits indicate that a 6 kV withstand 

capability may be sufficient to ensure device survival 

indoors, but a 10 kV withstand capability may be required 

outdoors. 

2.2 Timing of Occurrence 

Surges - occur at random times with respect to the 

power frequency, and the iaiiure mode oi equipment may 

be affected by the power frequency follow current. 

Furthermore, the timing of the surge with respect to the 

power frequency may affect the level at which failure 

occurs 141. Consequently, surge testing must be done with 

the line voltage applied to the test piece. 

3. Waveshape of Representative Surge Voltages 

3.1 Waveshapes in Actual Occurrences 

Indoor - Measurements in the field, measurements 

+h, 

rnns >auv~arvt 

1-I.---.+ --., 7, amw ..A *h 

rmlsvn ..--A sr~cal 

+:--I --,-..,-.:--- :-A: -

calcularlulm Iltulca

that most surge voltages in indoor low-voltage sy

tems have oscillatory waveshapes, unlike the wel

known and generaliy accepted uiiidiieciionai wav

specified in high-voltage insulation standards. 

surge impinging on the system excites the natur

resonant frequencies of the conductor system. As 

result, not only are the surges typically oscillator

but surges may have different amplitudes and wav

shapes at different places in the system. The

oscillatory frequencies of surges range from 5 kHz 

more than 500 kHz. A 30 to 100 kHz frequency is 

realistic measure of a "typical" surge for mo

residential and light industrial ac line networks. 

Outdoor - Surges encountered in outdoor location

have a!so been recorded, some being osci!htory !5

others. being unidirectional. Because the overridin

concern here is the energy associated with the

c,,-"-e 3 ,-,.ncc.w.,3+:,,,3 h,,+ Fa31;.-+;c. .-I-C,--;-+;~- -6 +h

2". 6L2, V LV".7LL .Y.*.L UU. L LU".,L'C "Lac1 1pL.V" Y' L"

surges can be derived from the long-establishe

specified duty of a secondary arrester, as detailed 

Paragraph 3.2. While this specification is arbitrar

it has the strength of experience and successf

usage. 

3.2 Selection of Representative Waveshapes 

The definition of a waveshape to be used as repre

sentative of the environment is important for the design o

candidate protective devices, since unrealistic require

ments, such as excessive duration of the voltage or ver

low source impedance, place a high energy requirement o

the sq?pressor, with jl res"!ti~g most pem!ty tc the e

user. The two requirements defined below reflect th

trade-off. 

Indoor - Based on measurements conducted by sever

indepei~deni uiganizaiions in iiO and 240 V system

(Appendix I), the waveshape shown in Figure 2 

reasonably representative of surge voltage in the

power circuits. Under the proposed description of 

"0.5 us x 100 kHz ring wave," this waveshape rises 

0.5 p, then decays while oscillating at 100 kHz, eac

peak being about 60% of the preceding peak. 

Figure 2. The Proposed 0.5 us x 100 kHz Ring Wave 

(Open-circuit Voltage) 

The fast rise can produce the effects associated wi

nonlinear voltage distribution in windings and th

dv/dt effects on semiconductors. Shorter rise tim

are found in many transients, but, as those transien

propagate into the wiring or are reflected fro

discontinuities in the wiring, the rise time becom

longer. 

The oscillating and decaying tail produces the effec

of voltage polarity reversals in surge suppressors o

other devices that may be sensitive to poiarit

changes. Some semiconductors are particularly sens

tive to damage when being forced into or out of 

conducting state, or when the transient is appiie

during a particular portion of the 60 Hz supply cyc

(Appendix 11). The response of a surge suppressor ca

also be affected by reversals in the polarity, as in th

case of RC attenuation before a rectifier circuit in 

dc power supply. 
The pulse withstand capability of many semiconductors tends to improve if the surge duration is much 

shorter than one microsecond. For this reason, the 

first half-cycle of the test wave must have a -,.sz;-:--* ,4..-..*:-.. JUI11LASI11 UUI aLIYII. 

Outdoor - In the outdoor and service entrance -.--..- * er~virur~~r~n~r, as we;; as in ~ocations dose to the 

service entrance, substantial energy, or current, is 

still available. For these locations, the unidirectional 

impulses long established for secondary arresters are 

more appropriate than the oscillatory wave. 

Accordingly, the recommended waveshape is 1.2 x 

50 us for open-circuit voltage and 8 x 20 ps for 

short-circuit current or current in a low-impedance 

device. The numbers used to describe the impulse, 

1.2 x 50 and 8 x 20, are as defined in IEEE Standard 

28 - ANSI Standard C62.1; Figure 3 presents the 

waveshape and a graphic description of the numbers. 

(a) Open-circu~t 

Voltage Waveform 

I li 

10. (b) Short-circuit Current 

(or Current in LowImpedance C~rcu~t) 

I //I \ 

Figure 3. Waveshapes for Outdoor Locations 

4. Energy and Source Impedance 

4.1 General 

Thenergy involved in the interaction of a power 

system with a surge source and a surge suppressor will 

divide between the source and the suppressor in accordance 

with the characteristics of the two impedances. In a gaptype suppressor, the low Impedance of the arc after 

-.r-....-.-. cnrarlmvar fnrrnc --.--'- mnct ...- ~f ?he enerov to di~cin~t~CI I. 0, r---- 

elsewhere: for instance, in a power-follow current-limiting 

resistor that has been added in series with the gap. In an 

energy-absorber suppressor, by its very nature, a substantial share of the surge energy .is dissipated in the 

suppressor, but its clamping action does not involve the 

power-follow energy resulting from the short-circuit action 

of a gap. It is therefore essential to the effective use of 

suppression devices that a realistic assumption be made 

about the source impedance of the surge whose effects are 

to be duplicated. 

The voltage wave shown in Figure 2 is intended to 

represent the waveshape a surge source would produce 

across an open circuit. The waveshape will be different 

when the source is connected to a load having a lower :--A....r^ -.A +ha Aan..^s +,. .., h;-h ;+ ir I,...,c.r ir &,,nr+;nn L"'~Ua"CC, a1IU LllZ UF61 FL LY WII1LII LL 1- ."..La La O 1UIILLI"II 

of the impedance of the source 161. 

TL- >_____ A_ ___L:^L :-..^A^^^^ ' :----*....* 11rc UC~, cc LU WB~JC~I JUULCC IIII~~U~IICC i3 IIII~UL LantI 

depends largely on the type of surge suppressors that are 

used. The surge suppressors must be able to withstand the 

current passed through them by the surge source. A test 

generator of too high an impedance may not subject the 

device under test to sufficient stresses, while a generator 

of too low an impedance may subject protective devices to 

unrealistically severe stresses. A test voltage wave 

specified without reference to source impedanc

imply zero source impedance - one capable of p

that voltage across any impedance, even a short 

That would imply an infinite surge current, cle

I,nrsal;r+;r r;t,,~+;r.n ",,.LO..a..L a.L"-..Ymm. 

4.2 Proposed Approach ' Because oi the wide range of possibie sou

pedances and the difficulty of selecting a specifi

three broad categories of building locations are pro

represent the vast majority of locations [7,8 I, fro

near the service entrance to those remote from 

source impedance of the surge increases from the 

to locations well within the building. Open

voltages, on the other hand, show little variation 

building because the wiring provides little attenuati

Table 1 outlines the three categories of building wir

Table 2 shows open-cirtuit voltages and short

currents for each of the three categories. The 

deposiied in a 500 'v' suppressor has been coiiipuie

shown for each of the categories. 

TABLE l 

Locatlon Categories 

A. Outside and Service Entrance 

Service drop from pole to building ent 

Run between meter and distr~bution pa 'I 

Overhead line to detached build~ngs 

Y 

Underground lmes to well pumps 

B. Major Feeders and Short Branch Circuits 

nic+.;)...*in.. ..=.-I A-.,ir-c "La.. ."".."" y"ll.1 ".LC. 

n, 2nd feeder SYS?PmS in ind.s?ria! n~;lntr 

Heavy appliance outlets with "short" ronnertion

to the service entrance 

Lightmg systems In commerc~al bulldlngs 

C. Outlets and Long Branch Circults 

All outlets at more than LO m (30 ft) from 

Category B with wires 1114-10 

All outlets at more than 20 m (60 ft) from 

Cateeorv A with wlres 1114-10 

TABLE 2 

Ranges of Voltage and Currents 

Energy D

Max~mum ~ted ~n a 

, -,--..,.-... 

L"L-.."am mpu!s- $Unnrps

A. Outdoor and 0 10 kV 1.2 x 50 Us tor 

Serv~ce h~gkmpedance c~rcults 

Entrance 10 kA 8 x 20 w for 

low-~mpedance crrcults 150 

B. Major Feeders 06 kV 1.2 x 50 Ps for 

and Short hlgh-impedance clrcults 

Branch 03 kA 8 x 20 Ps for 

Clrcu~ts ~mpedance clrcults 40 

l 6 kV 0.5 )IS x 100 kHz 

for htgh-impedance clrcults 

0500 A short clrcult for 

low-~mpedance clrcults 2 

C. Long Branch 06 kV 0.5 us x 100 kHz for I c a hgh-aipd~ce caicuii. 1 outlets 200 A short clrcult for 

low-impedance clrcults 0

The values shown in the table represent the m

range, corresponding to the "High Exprsure" situ

Figure 1. For less exposed systems, or when the p

of a failure is not highly objectionable, one could 

lower values of open-circuit voltages with corres

reductions in the currents. 
5. Conclusion 

The broad range of surge voltages occurring in lowVO!?~~P ac Fwer circuits can be simu!ated by a limited set 

of test waves, for the purpose of evaluating their effects 

on equipment. 

Field measurements, laboratory experiments, and 

calculations indlcate that two basic waves, at various opencircuit voltages and short-circuit current values, can 

represent the majority of surges occurring in residential, 

commercial, and light industrial power systems rated up to 

600 V rms. 

txceptions will be found to the simplification of a 

broad guideline; however, these should not detract from the 

benefits that can be expected from a reasonably valid 

uniformity in defining the environment. Other test waves 

of different shapes may be appropriate for other purposes, 

and the present guideline should not be imposed where it is 

not applicable. 

6. Acknowledgments 

The members of the IEEE Working Croup contributed 

the data, shown in Appendix I, that shaped this guideline. 

Heipiui comments, discussions, ana reviews by ail members 

of the Surge Protective Devices Committee are also 

acknowledged. The author is particularly indebted to the 

contributions of Catharine Fisher and Peter Richman for 

the presentation and discussion of the concepts and 

recommendations made in this guideline. -- Append~~ 1 - Data Base 

Recordings and surge counter data have been contributed from several sources, in addition to the surge 

counter data obtained by members of the working group. 

Representative oscillograms and summary statistics are 

reprodtic& i:: this appendix, in rnppcrt cf the vc!?age !eve!s 

and oscillatory wave proposals. 

I. R~cordrngs by Bell Telephone Laboratones - 

(Data contributed by P. Speranza, internal report, 

unpublished to date) 

1.1 Typical Surge Counter Statistics 

120 V line at BTL facility in ester, New Jersey, 

during 42 months of monitoring: 

I46 counts at 300 to 500 V 

14 counts at 500 to 1000 V 

3 counts at 1000 to 1500 V 

3 counts above 1500 V 

!,2 Typlca! Automatic Recordine Oscilloscopes 

0 20 40 60 80 100 120 ps 

120 V OUTLET. LABORATORY BENCH 

277/480 V SERVICE ENTRANCE 

2. Recordings by General Electric Company 

(Data contributed by F.D. Martzloff [ 2 1 ) 

2.1 Surge Counter Statistics 

a) Three percsn: of a!! C.S. residences experience 

frequent occurrences (one per week or more) 

above 1200 V 

b) There is a 100:l reduction in the rate of device 

failure when the withstand level is raised from 

2 kV to 6 kV. 

2.2 Typical Automatic Recording Oscilloscopes 

0 5 10 20 ?O~OM~~IOOUS . . FURNACE IGNITION 24 HOUR PERIOD 

2.3 Simulated Lightning Strokes on a Residential Power 

Circuii iiaboratory ~odei oi Sysiem j i 9 1 

.Recording of open-circuit voltage 

at a branch circuit outlet: 

2200 V peak 500 kHz oscillations 

By connecting a 130 R load at the same outlet (lA load) the voltage 

is reduced to 1400 V peak, with more damping. 

-.--a .:.-- F--- TL:- T--* c--:-- LUIICIU5IUIIS rIUlll 11115 lC5L XI IT5 

i. A curreni of i.5 kA imoderaie for a iighining 

discharge injected in the ground system) raises 

the wiring system of the house 2.2 kV above 

ground. Four kiloamperes (still a moderate 

value) will bring this voltage to 6 kV, the 

typical flashover value of the wiring. 

2. A natural frequency of 500 kHz is excited by a 

unidirectional impulse. 
3. In this example, the source of the transient 

(from the loading effect of 130 a) appears as 

3. Statistics By Land~s and Gyr Company 

Surge counter data on various locations in Swiss 220 V 

systems (Data contributed by L. Regez - unpublished to 

date) 

The General Electric counter statistics y

point of 1200 V at about 1 occurrence per ye

The General Electric clock data indicate a sl

iOO:i from i itit to 6 kv i- - - -j. 

The Regez data prov~de a band for the majo

- Inrstinnc - - - - (chnwn rrncc-hstrhorl\ with thn n- - . . - . - . . - . . . . - . --I . . - I - . . - - , , . . . I. . ...- tion of the rural location with long overhea

which has more occurrences. 

Working Group statistics (. -- . --) indicate 

steep slope, perhaps because of the influen

outdoor locations Included in the sample (s

to the rural data of Regez). 

The proposed curve, which is the center of th

range of Figure 1, is shown In bold dashed lines (- - 

It has been drawn at the 100:l slope, passing near th

and General Electric points and located within the b

the Regez data. 

'" 102 2 5 10' 2 5 10' 2 

PEAK VOLTAGE V 

- Servrce entrance, 16-famdy house, underground system 

--- Same house, outlet third floor hvmg room 

- - . -- - - . 

Same house, ourlet fifth floor lmmg room 

krvlce entrance of bank burldrng m Barel --- Landlr and Gyr Plant. Zug, outlet m lab. 

Landlr and Cyr, Zug, outlet in furnace room 

Farmhouse rupplled by overhead lmes 

4. Working Group Surge Counter Statistics 

Surge counters with four threshold levels (350: 500: 

1000, and 1500 V) were used to record surge occurrences at 

various iocations. Members oi the Working Group instaiied 

these on 120 and 240 V systems of various types, including 

the following: outlets in urban, suburban, and rural 

residences; outlets in a hospital; secondary circuits on 

distribution system poles (recloser controls); secondary of 

padrmounted distribution transformers; lighting circuits in 

an industrial plant; life test racks at an appliance manufacturer; bench power supply in a laboratory. 

Summary Statistics of these measurements are as follows: 

Data base from 18 locations with a total recording 

time of 12 years spread over 4 calendar years, 

using 6 counters. 

Number of occurrences per year (weighted averages) at ?'average iocaiion.!' 

e 350 V: 22 

e 500 \.I: !! 

0 1ooov: 7 

0 1500 V: 3 

Significant extremes 

One home w~th large number of surges 

caused by washer operation. 

Four locations out of 18 never experienced a 

surge. 

0 One home experienced several occurrences 

above 1500 V, with none below that value. 

0 One industriai iocation iswitching oi a test 

rack! produced ?housands of surges in the 

350-500 V range, and several surges in 

excess of 1500 V. This location was left out ,-.f +hn ~.,.~=,na mrnnn~+=ti,-.n hn~t it nvnrnnli- V' L.'.. O.L.UbL ..V...,,U.Y..V.., 1". 1. --.....,.,..- 

fies a significant extreme. 

From the data base cited in the preceding pages, one 

can draw the chart below, including the following information on voltage vs frequency (rate) of occurrence: 

1. The Bell Laboratories data yield a point of 1000 V 

at about 2 occurrences per year (-). 

PEAK VOLTAGE - V 

Appendix 11 - Effect of Transient Polarity Reversa

oii S~iiii~~iidii~t

Breaitaown of sem~conaucrors under varlous 

tlons of load and translent overvoltage appl~rat~

been 1nvest1~ated.t Ev~dence 1s presented In th

mvestlgatlons c~ted that a reverse voltage apphed 

the conduct~on per~od of the power frequency pro

lower breakdown voltages than the apphcat~on of the 

translent w~th no load or durmg blocking. Example

glven below, taken from these two mvestlgatlons, sh

stat~stlcally slgnlf~cant d~fferences In the voltage leve

IN1 190 Diode* 

Average 

Breakdown 

Transient at no load 1973 

Fast wave under load 830 

Slow wave under load 1097 

Transient at no load 2056 

Fast wave under load 894 

- Zlnw wave ~tnrler lnarl - - . . . - . - - . . - - . . - - - .--- I Inc. 

Translenr appiiea ar: 

- peak of reverse voltage 1766 

-25" after start of conductron 1181 

-90' after start of conduction 906 

-155' after start of conduction 1 115 

This effect is one of the reasons for selecti

oscillatory waveform to represent the environment: 

be more hkely to Induce sem~conductor fa~lures t

. unidirectional wave. Also, it shows the significance 

timing of the transient appl~cation with respect t

power frequency cycle. 

Appendix I11 - Notes and References 

1. Surge Voltage 

Deilnmons oi terms used in this guideiin

cc~jijtent with !EEE Sr=&=rd !aQ-!977,Dicti~q> cf 

trical and Electronic Terms, 2nd ed.; however, som

ferences exist. For instance, IEEE Std 100-1977 def

sijrge as a " -..--- :--* -' --*--A:-' -- 

LI~II~CIIL wave ur ~ur IFIIL, ~ULFIILIPI UI pu

the electric circuits'--a definition broader than tha

*Chowdhuri, P., "Transient-Voltage Characteristics of 

Silicon Power Rectifiers," IEEE IA-9, 5, September1 

October 1973, p. 582. 

t F.D. Martzloff, internal report, unpublished. 
here. Transient overvoltage is defined as "the peak voltage 

during the transient condition resulting from the operation 

of a switching devicef'--a definition more restricted than 

that of the present guideline. 

2. Amplitudes of Strikes, Worst Case 

The siiige voltages described in this giiideiine include 

lightning eff& on ~ower systems? mostly strikes in the 

vicinity of a power line, or at a remote point of the power 

system. Tne iiterature describes rhe irequency oi occurrence vs amplitude of lightning strikes, from the low levels 

of a few kiloamperes, through the median values of about 

20 kA, to the exceptional values in excess of 100 kA. 

Clearly, a secondary arrester rated for 10 kA can protect 

adequately in case of a mild direct strike, or of a more 

severe strike divided among several paths to ground. 

However, a very high and direct strike will exceed the 

capability of an ANSI-rated secondary arrester. 

References: 

Cianos, N. and E.T.Pierce, A Ground-Lightning Environment for Engineering Usage, Stanford Research Institute, 

ivienlo Park, CA 94205, A"g"5t i972. 

Bodie, D.Y., A.1. Ghazi, ivi. Syed, and 2.i. Yoods~de, Characterization of the Electrical Environment, Toronto and 

Buffalo, N.Y.: University of Toronto Press, 1976. 

Martzloff, F.D. and G.J. Hahn, "Surge Voltage in Res~dential and Industrial Power Circuits," ZEEE PAS-89, 6, July/ 

August 1970, 1049-1056. 

3. Level vs Rate of Occurrence 

The relationship between the level and the rate of 

occurrence of surges is partly caused by the attenuation of 

the surges as they propagate away from the source of the 

surge and divide among paths beyond branching points. 

Equipment at a given point will be subjected to a relatively 

small number of high-level surges from nearby sources, but 

to a larger number of surees from more remote sources. 

$. T;-;nm -6 Cn,wm-c ..,;+h D-.- .-.-+ +- D-..,-.. C---..---.. .A. ,,All6 "I -."a 6F.. w A,,, L\CJ~CLL L" I "WC, 1 ,C.,UF,IL)I 

Lightning surges are completely random in their 

timing with respect to the power frequency. Switching 

siirges are iikeiy to occiir near oi after current zero, but 

variable load power factors will produce a quasi-random 

distribution. Some semiconductors, as shown in Appendix 11, exhibit failure levels that depend on the timing of 

the surge with respect to the conduction of power 

frequency current. Gaps or other devices involving a 

power-follow current may withstand this power follow with 

success, depending upon the fraction of the half-cycle 

remaining after the surge before current zero. Therefore, 

it is important to consider the timing of the surge with 

respect to the power frequency. In performing tests, either 

complete randomization of the timing or controlled timing 

should be specified, with a sufficient number of timing 

coditions to ievea! the i?iojt eriticai timing. 

the "classical lightn s been established as 

1.2 x 50 ~s for a voltage wave and 8 x 20 ps for a current 

wave. Evidence has been coiiected, however, ro show that 

oscillations can also occur. Lenz reports 50 lightning 

surges recorded in two locations, the highest at 5.6 kV, 

with frequencies ranging from 100 to 500 kHz. Martzloff 

reports oscillatory lightning surges in a house during a 

multiple-stroke flash. 

References: 

Lenz, J.E., "Basic Impulse Insulation Levels of Mercury 

Lamp Ballast for Outdoor Applications," Illuminating Engrg., 

February 1964, pp. 133-140. 

Martzloff, F.D. and G.J. Hahn, "Surge Voltage in Resi- 

&n?ia! a~d !ndus$ri=! ?~I\wP~ Circcif !EEE PACg_O, 6, Ju!~! 

August 1970, 1049-1056. 

6. Surge !mpedance 2nd Source !mpedt.nce 

To Drevent misunderstandina. a distinction between source impedance and surge imped&ce needs to be made. 

Surge impedance, also called characteristic impedance, is a 

concept relating the parameters of a long line to the 

propagation of traveling waves. For the wiring practices of 

the ac power circuits discussed here, this characteristic 

impedance would be in the range of I50 to 300 Q, but 

because the durations of the waves being discussed (50 to 

20 ps) are much longer than the travel times in the wiring 

systems being considered, traveling wave analyses are not 

useful here. 

Source impedance, defined as "the impedance 

presented by a source of energy to the input terminals of a 

device, or network?! iiEEE Standard iOOi, is a more useiui 

concept here. 

7. Power System Sou~ceknpedance 

The measurements from wh~ch Fl~ure 1 was derived 

were of voltage only. Little was -known about the 

impedance of the circuits upon which the measurements 

were made. Since then, measurements have been reported 

on the impedance of power systems. Bull reports that the 

impedance of a power system, seen from the outlets, 

exhibits the characteristics of a 50a resistor with 50 pH in 

parallel. Attempts were made to combine the observed 

6 kV open-circuit voltage with the assumption of a 

50N5O pH impedance. This combination resulted in low 

energy depos~t~on capab~lity, which was contradicted by 

field experience of suppressor performance. The problem 

led to the proposed defmition of oscillatory waves as well 

as high-energy unidirectional waves, in order to provide 

both :he eff?c:s of aii ~sci!kt~ij: wa'w and the high-energy 

deposition capability. 

Reference: 

Bull, J.H., "Impedance of the Supply Mains at Radio 

Frequencies," Proceedings of 1st Symposium on EMC, 

75CH1012-4 Mont., Montreux, May 1975. 

8. Installation Categories 

Subcommittee 28A of the International Electrotechnical Commission has prepared a report, referenced below, 

in which installation categories are defined. These 

installation categories divide the power systems according 

to the location in the building, in a manner similar to the 

location categories defined in this guideline. However, +hara are *;"-;$;--..+ A;*$ ------- h *L.- * LB~LSL avlllL >r688AAAL'ImnL ULIICICIICCJ UCLWCCII LllC LWU 

concepts. First, the IEC categories are defined for a 

"Controlled Voltage Situation," a phrase that implies the 

presence of some surge suppression device or surge 

attenuation mechanism to reduce the voltage levels from 

one category to the next. Second, the IEC report is more 

concerned with insulation coordination than with the 

application of surge protective devices; therefore it does 

not address the question of the coordination of the 

protectors, but rather the coordination of insulation levels 

- that is, voltages. Source impedances, in contrast to this 

guideline, have not been defined. Further discussion and 

work toward the application guidelines of both documents 

should eventually produce a consistent set of recommendations. 

Reference: 

ov la ti on Coordination Within Low-Voltage Systems Including Clearances and Creepage Distances for Equipment, 

internationai Eiectrotechnicai Commission, Report SCi8A 

[Central Office) 5; to he puh!lshed in !979, 

9. Open-Circuit Voltages and Wiring Flashover 

Surges propagate with very little attenuation in a 

power system with no substantial connected loads. 

Measurements made in an actual residential system as well 

as in a laboratory simulation have shown that the most 

significant limitation is produced by wiring flashover, not 

be attenuation along the wires. Ironically, a carefully 

insulated installation is likely to experience higher surge 

voltages than an installation where wiring flashover occurs 

at low levels. Therefore, the open-circuit voltage specified 

at the origin of a power system must be assumed to 

propagate unattenuated far into the system, which is the 

reason for maintaining the 6 kV surge specification when 

going from the "B" location to the "Cut !ocation. 

References: 

Martzloff, F.D. and K.E. Crouch "Coordination de la 

protection contre les surtensions dans les r6seaux basse : :: a, .. .. rcl~a~vtt I CXUCII urn, - rrucaearngs, is78 iEEE Canadian 

Conference on Communications and Power, 78CH1373-0, 

pp. 451-454. 

Martzloff, F.D. Surge Voltage Suppression in Residential 

Power Circuits, Report 76CRD092, Corporate Research 

and Development, General Electric Company, Schenectady, 

N.Y., 1976.