Measurements of Voltage and Current Surges on the AC Power Line in Computer 

and Industrial Environments

R. Odenberg and B.J. Braskich

Transtector Systems, Inc.

Reprint, with special permission, of IEEE Transactions PAS-104, October 1985

With discussion submitted by

Peter Richman

KeyTek Instrument Corp. 

and 

François D. Martzloff

General Electric Company

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Significance:

Part 3: Recorded surge occurrences and surveys 

Part 5: Monitoring instruments

This paper was approved for presentation at the 1985 PES Winter Meeting to foster discussion of a new 

approach for recording the occurrence of voltage surges as well as current surges, the latter being a new 

contribution to characterization of the surge environment.

Unfortunately, according to the discussions resulting from the presentation, some limitations or possible 

artifacts of the instrumentation raised question on the validity of the data. For that reason, the complete 

paper and its discussion have been included in the anthology
IEEE Transactions on Power Apparatus and Systems, Vol. PAS-IM, No. 10. Oaober 1985 

Measurements of Voltage and Current Surges 

on the AC Power line in Computer 

and Industrial Environments 

R. Odenberg 

Transtector Systems. Inc. 

Hayden Lake, Idaho 83835 

Abstract - Speci a1 computerized instrumentation 

was developed for monitoring and recording voltage 

and current surges on the A.C. power line in computer 

and industrial environments. 

From January, 1982. until December, 1983. locations in nine cities were surveyed. The total number 

of surge occurrences measured during the test period 

was 277,612. Monitoring and recording of data was 

accomplished utll i zing computer based equipment. At 

a later time the data was transmitted to a central 

computer to tabulate. 

Two important factors measured and recorded by 

the computerized systems were: (1) the system 

measured both voltage and current peak values during 

the transient occurrence, and (2) the' time to peak 

voltage and current and time to 50% of peak. This 

provided a correlation between the voltage and 

current of a specific surge occyrrence. 

Measurements were made at different points in AC 

power systems from a 15Al120VAC service outlets to an 

AC power mains. 

This report provides the tabulated data. calibration tests, describes the site installation and 

the conditions of the envi ronment when the measurements were taken. 

The results show that the composite voltage and 

current waveforms represented a 1.07 x 1002.01 us 

voltage wave and a 60.4 x 999.34 us current wave. 

INTRODUCTION 

Voltage and current surges occurring on the AC 

power line has caused considerable problems to both 

users and manufacturers of electronic systems. The 

need to eliminate this problem is essential today for 

efficient operation. 

The earliest reports on transients appear in 

published papers [I] 1969. [2] 1974, and a more 

current report [31 1980. 

These reports discuss and describe only the 

voltage characteristics of the transient and no data 

is provided on the current characteristics of the 

same transient. 

This paper provides data taken in the field on 

the composite waveforms of peak voltage and current 

together for each transient occurrence. Special 

equipment was developed for detection and measurement 

of these occurrences. 

The senstng ctrcuits (current and voltage) were 

designed to have conditioned signals for an input to 

a computer based system. The purpose of this paper 

is to present the data. Uith this information, 

improved testing for the susceptibi lity of electronic 

equipment and systems can be accomplished. 

85 'dl 243-1 A paper recommended and approved 

by the IEEE Surge Protective Devices Committee of 

the IEEE Power Enaineering Society for presencation at the IEEEIPES Winter Fleecing, New York, 

#eu York, February 3 

red August 31, 1984; 

November 28, 1984. 

1985 

- 8, 

made 

1985. Manuscript submitavailable for printing 

INSTRUMENTATION 

There are several problems in measuring voltage 

and current surges and currents in the fteld (11. 

First, the instrumentation cannot be' moni tored all 

the time. The system incorporated a memory to store 

data until the data was transmitted to the main 

computer. The second problem is sensing and 

recording voltage and'current values in microsecond 

times and maintaining the accuracy of the time base. 

The third problem is possible distortion of the transient waveforms by the sensing circuits. These 

probtems were experienced during prototype testing 

and were compensated for in the subsequent equipment 

design. Tests were performed on the systems to 

verify results, as shown in the calibration section. 

Waveform Format - The format of sensing and 

recording the data was chosen to be consistent with 

the waveforms presented in ANSIIIEEE C62.41-1980.[5] 

(See Figs. 1 and 2). These waveforms (1.2 x 50 us 

voltage and 8 x 20 us current) are described by two 

points, a calculated time to peak and a time to 

delay. There are no other points described in these 

waveforms. The waveforms presented In this paper 

Fig. 3 are the peak values. the measured time to peak 

and the measured time to 50% of peak value. 

(a) OpenCircuit Waveform. 

(b) D;rrhUpe Cumnt Waveform. 

FIG. 1 Wavelonnr From ANSlllEEE C 62.41-1980 

0018-9S10/8S/1000-268ISOI .00@1985 IEEE 
FIG. 2 Table From ANSIIIEEE C 62.41-1980 

FIG. 3 Defmt~on ol Waveform Tlme Polnts 

Voltage and Current Measare~nents - The voltage 

surge measurements were made line to neutral, 

excluding the A.C. line voltage. The current surge 

measurements were made with a sensing circuit in 

series with the A.C. line. The system nulls out the 

AC line current. 

Correlation of Voltage and Current Surges - The 

computer system looks at the time between voltage and 

current surges and decides whether they are associated with each other. They are correlated as the 

same occurrence when the time between a voltage- and a 

current surge is less than 50 us. This is true 

whether the voltaqe leads or laqs the current surqe. 

Description of Surge ~nalyz-er - The surge analyzer will sense, digitize and record voltage and 

current transients appearing on the AC power line. A 

block diagram of the system is shown in Fig. 4. The 

complete system is powered by batteries. The system 

senses either positive or negative surges. As each 

voltage/current surge occurs, the following parameters are captured and stored: (1) peak voltage 

(\lp), time to peak, time to 50% of V , (2) peak 

current (Ip), time to peak, time to 5& of Ips (3) 

date of occurrence. 

FIG. 4 Transmi VollagelCurrent 

Analyzer Block D~agram 

Analog and Digital Modules - (Fig. 4). The 

Analog Module receives from the sensors transient 

voltage and current on an AC power line by converting 

the voltage and current inputs to digital signals. 

The Uigital Module processes the digital information 

to the system microprocessor. 

Microcomputer Control Module (Fig. 4). This 

module has overall control of the Analyzer. It 

receives the peak values and time collected by the 

Digital Module for each transient md along uith the 

scale factors from the Analog Module, determines the 

characteristic of the transient. It records the date 

of occurrence of each transient. It contains a real 

time 24 hour clock which can. be set by an operator 

using the numeric keypad. 
Voltage and Current Sensors - Fig. 5 shows 

levarate voltage and current inputs to the computer. 

he sensors provide the means to conduct only the / surge voltage and current into the Analog Module. 

Both voltage and current values have an accuracy of 

' 4%; 1.e.. a recorded 300 volt transient could really 

Kc 285 volts or It could be 315 volts. The time to 

peak and to SOX of peak has an accuracy of 5%. The 

sensing circuits measure the peak voltage and current 

related to time and the return of both to SO% of the 

peak value of both. 

z 

x 

.9 - - C 

9 - 0 $ FIG. 7 Transient analyzer - single phase12 w~m 

S - - 4 

- 

3 

P 

0 

p 

v 

< 

I 

Mlcmmwter Control Module Interface 

FIG. 5 SemmlAnalog Detailed Block Diagram 

Figures 6, 7, and 8 arc photogr~l)hs of three different AC power transient analyzers. 

FIG. 8 Transient analyzer - 3 phase14 wire 

(part 1 of 2 pieces) 

Calibration Tests - To verify that each su

analyzer correctly recorded and reproduced the w

forms measured, a calibration test was perform

The setup is shown in Fig. 9. The calibration c

sisted of nine waveform tests, four voltage, f

current. and one combined voltage and current wa

forms. They are shown in Fig. 10 through 18 and 

output results from the transient analyzer is sh

in Fig. 19. 

flG. 8 Transient analyzer - slngle phase13 wire 
FIG. 9 Block Diagram for Caltbralcon Tests 

FIG. 10 Callbrat~on Test n3: Voltage 

Honzontal scale. IOuslD~v 

Vencal scale: 1000V I DIV 

FIG. 11 Caliorat~on Test n 1 - Vollage 

nonzontal scale: 10us1Div 

Verllcal scale. 200VIDlv 

FIG. 12 Callbrat~on Test r4. Current 

Honzonlal scale: lOus/Div 

Verrtcal scale. IOAIDIV 

FIG. 13 Cahorat~on Test r2: Voltage 

nonzontat scale: IOU~IO~V 

Ven~cal scale: SOOVIDIV 

FIG. 14 Cal~brat~on Test r5: Current 

Honzontal scale: 1OusID1v 

Vertical scale. IOOAlDtv 
Description of Sites and Installation of 

Analyzer - A variety of locations were selected in 

computer and industrial facilities. These facilities 

were selected because they were unprotected environments. The only suppression that was installed at 

these environments were on the primary side of the 

building transformer and were either gas tube or air 

gap type. Location codes were established as shown 

be1 ow: 

- Code Location 

1 = 15Al120 VAC receptacle 

2 = 30A/ 120 VAC receptacle 

3 = 100A/208/120 3 phase 4 wire subpanel 

4 = 400A/240/120 1 phase 3 wire subpanel 

5 = 800A/208/120 3 phase 4 wire main 

6 = 1200A/208/120 3 phase 4 wire main 

7 = 800A/480/277 3 phase 4 wire main 

A typical electrical installation of the surge analyzers is shown in Fig. 20. 

All of the circuits that the analyzers were connected to were under load. All power conductors 

under test entered and exited the analyzer. 

RESULTS 

A computer random sampl ing, one selection per 

test site per test period is shown in Fig. 21. The 

total number of occurrences recorded over the two 

year period was 277,612. The summarv of all 277.612 

measured voltages, currents and times are shown. in 

Fig. 22 and Fig. 23. 

TIME (US) TU 

FIG. 22 

I 00 

I 

FIG. 20 Example of a S~ngle Phase Installatton 

The composite waveforms voltage and current 

the total numbers of occurrences is 1.07 x 1002.0: 

voltage and a 60.4 x 999.34 us current. The cal 

lated percentage of waveforms that fall within ! 

of this composite waveform is 89.4%. A compi 

printout of the composite waveform is shown in F 

24 voltage waveform and Fig. 25 current wavefc 

Rounding off the numbers, the waves then reduce t 

x 1000 us voltage and 60 x 1000 us current. 

TABLE I11 SUMMARY OF VOLTAGE WAUEFORM UALUES 

TIME (US) TO TIRE (US) TO 

PEAK '1 asox n~ runu~*~z 

1 nrAT l nN COW fllN nHX M 1 N RAX 

1 3.3 98.1 7.0 1271.3 

UOLTAGE (U 

AVFRAGE 

347.1 

399.5 

550.2 

651.4 

1520.5 

1633.7 

1230.3 

CURRENT (A) 

AVERAGE 

40.5 . 

TABLE lV SUMMARY OF CURRENT WAVEFORM VALUES 

FIG. 24. Compos~te Voltage Waveform ' FIG. 25 Composite Cunent Waveform ' 

Note: Thew graphs am strlctly a computer drawn waveform. The only placoa on tho graphs that am ncuratm am Uu p.dc 6 

50% points wltago or current, and the time lo reach these points. 

CONCLUSION 

This data provides confirmation on the existence 

of longer voltage and current waves than has been 

traditional ly used. It provides new guidance for 

testing for susceptibility and vulnerability of 

equipment. Further work is being continued in this 

area and as results become available they will be 

documented. 

REFERENCES 

[l] Hartzloff. F.0 and Hohn, G.J. 

Surge Voltage in Residential and Industrial 

Power Circuits. LEEE Transactions on Power 

Apparatus and Systems PAS-89, JulylAug 1970. pp 

1049-1056. 

[2] A1 len, G.W. and Segal , 0. 

Monitoring of Computer Installations for 

Power Line Disturbances. Conference Paper C 74 

199-6 IEEE PES Winter Meeting. New York, 1974. 

[3] Goldstein, M. and Speranza, P.D. 

The Quality of U.S. Commercial Power. Intelec 

Conference Proceedings , 1982. pp 28-33. 

[4] General Electric Semi -Conductor Product 

Department, Transient Voltage Suppression 

Device Selector Guide, Publication 600.40, 

Page 3, 1983. 

[5] ANSIlIEEE Std. C62.41-1980. IEEE Guide for 

Surge Voltages in Low-Voltage AC Power 

Circuits. 
Discussion 

tcts Ricbman, (KeyTek Instrument Corp., Burlington, MA): The 

authors state that 89.4% of the 227,612 observed surges in a total of 

anc cities had durations lying within a f 10% band centered around 

, ldr composite waves' approximately 1000 @durations, for both voltage 

I and current. 

, The 89.4% figure for the entire population implies that for every surge 

with duration less than about 900 ps or greater than about 1100 ps, there 

were nine with durations in the 900 to 1100 p interval. Long waves have 

mtainly been reported in prior literature. However, duration consistency 

of the sort reflected here would seem more likely to be an artifact than 

I characteristic of the random phenomena being monitored. 

Manuscript received February 25. 1985 

Fnneois D. Martzloff (General Electric Company, Schenectady, NY): 

"Measurements of Voltage and Current Surges on the AC Power Line 

in Computer and Industrial Environments" by R. Odenberg and B. J. 

Braskich is a welcome contribution toward a more complete characterization of the surge environment in low-voltage ac power circuits than had 

heretofore been available. Its value could be considerably enhanced, 

however, if the authors would provide in their closure the answers to 

the questions presented here, together with a clarification of some 

concepts. 

Following general comments on concepts, questions will be presented 

as separate entities in order to facilitate the dialogue with the authors 

and the reading of the final Transactions document. Some of these questions, however, are interrelated in terms of the total impact of the paper. 

Gcneral Comments 

I. Waveform versus Data Points 

The authors state in the "lntroduction" that the paper provides data 

on waveforms recorded in the field. This statement raises great interests 

and expectations among the workers associated with the subject. Unfortunately, the data actually present only two points of the infinitely 

diverse waveforms that can occur in the real world. 

When the authors state, in "Instrumentation," that two points. . .no 

other points are described.. .in the ANSI/IEEE C62.41-1980 

waveforms.. . . ." there seems to be a confusion of interpretation. The 

C62.41 waveforms and those of other standards are indeed described 

by the citation of only two points, but these waveforms are defined 

mathematically by precise equations used in numerical methods. The two 

points cited to describe the wave merely form a shorthand label to reprexnt a wave that has been produced, recorded, and accepted as completely 

defined. 

In contrast, what the authors attempt to do is to fit the diverse realworld waveforms (none of which has been recorded by them) into a 

simplified "composite" envelope. The parallel suggested by the authors 

between the two points of Standard C62.41 and their fwo points is 

therefore inappropriate. 

This simplification is more than the old issue of simplification of the 

world for the sake of repeatable and comparable results in the laboratory, 

because in this case we have no indication of what the waves which are 

being simplified actually represent. Attaching the qualifier "composite" 

to the word "waveform" is perhaps an attempt at clarification, but its 

use only adds to the confusion. 

2. Computer-Drawn Waveform 

The risk of confusion is further develoeed by the drawing of "com~osite 

clude some with known diverters inrtalled downstream from 

the instruments? 

Questions on Instrumentation Characteristics 

1. Frequency Response 

The authors state that the ac line voltage is "excluded" and the ac 

line current is "nulled." With the reported vast majority (90%) of the 

tails closely packed around 1 ms (the statement "89.4% within * 10% 

envelope"), and with the 60 Hz ac signals having a half-period of only 

8 ms, one wonders what this exclusion or nulling might do to the surge 

signals. A complete scan of the instrument response versus frequency 

would clarify this issue. 

Question 2: Have the authors considered calling upon an independent 

laboratory, to characterize the instrument? 

2. Threshold and Voltage-Current Correlation 

The authors do not state a threshold in their measurements to help 

define what is being considered as a "surge" by the instrument. 

Question 3: If the voltage-current correlation is being decided according 

to the criterion "the time between a voltage surge and a current surge is less than 50 ps," is this decision based upon 

the reaching of the unstated threshold for each current and 

voltage signal? 

Since most current surges have a time to peak in excess of 50 p, the 

peak presumably cannot be used as the basis for the decision. A more 

detailed explanation of the stated correlation would be helpful. 

3. Recovery after Recording - 50% Tail Dejinition 

The authors show in Figs. 16 and 17 simple decaying oscillations where 

it is apparent that the first passage through 50% of the crest after the 

peak will produce the recording of the time elapsed as the time to 50%. 

. - waveforms" in Figs. 24 and 25. The warning note addedto these figures 

might serve as a reminder of their computer origin. However, busy readers 

are likely to remember only that the paper has shown the world to contain 1 X 1000 or 60 X 1000 surges whereas, in fact, all the paper has 

shown is a recording of two points. To avoid misleading information. 

Figs. 24 and 25 should be deleted. 

3. Exclusively Linear Loads 

The authors state that the currents recorded are those associated with 

the loads downstream from the instrument. They say, further, that no 

surge suppressor was included in the loads. 

Assuming that indeed the authors had complete access to and 

knowledge of the loads, which knowledge would guarantee the validity 

of the statement, it seems unfortunate that the measurements did not 

include a period of time with a known surge diverter connected across 

the line. 

A very useful application of current recordings made possible by the 

authors' new instrument would be the determination of what current the 

unknown transient source would inject into a nonlinear surge diverter, 

in contrast to the linear loads described by all the data of the paper. 

Question 1: Do the authors intend to extend their measurements to inQuestion 4: However, what would be the response of the instrument to 

complex waveforms such as those of Figs. A, B, C, D, and 

E, shown below? 

Question 5: Would the instrument record points (a), (b), (c), (d), and 

(c), rcpectively, as 50% points on those waves or record a 

later 50% passage% 

Question 6: When triggered by a threshold, and busy recording the 50% 

passage, does the instrument have a recovery time before 

it can record a subsequent peak of the same event, and then 

will it cite only the highest point of the total event? 

Question 7: Does the instrument record an unconnected second event 

that occurs soon after the first? 

Statistical Aspects of the Data 

The following questions and comments reflect my own concerns as 

well as those of G.J. Hahn, coauthor of the 1970 paper cited as Ref. 

111 of the Odenberg and Braskich paper. 

1. Sampling Procedures and Definitions 

Further clarification of the site sampling procedures and definitions 

of surges would be useful. In particular, 

a. The survey involved nine cities and seven locations. 

Questions 8: Does this statement mean that there were 7 locations in 

each of the 9 cities, or a total of 63 "places?" 

(Table 11 shows 45 combinations.) 

How were thc locations in each city selected? 

*Can these be regarded as a random sample? 

6. The nine cities used should be specifically named in Tables I11 and 

IV and some statement made as to why they were selected. 

Questions 9: Is there a standard definition of a surge? 

Is it the same from one city, location. and place to the 

next? 

It would be very useful to present the data of Table I1 with an indication of the per-unit levels of the peak voltage values recorded, because 

the system voltage varies with the location code. 

2. Summary oj the Study Resulrs 

The value of the information presented would be considerably enhanced 

if the authors could provide additional information. The limitation on 

page numbers imposed by IEEE on submitted papers is acknowledged. 

but the closure could be the opportunity for this enhancement, as follows: 

a. Figs. 22 arid 23 provide key information. The tabulation could be 

broken down by the 63 (?) places and summaries provided for location and, possibly, city (and also overall). 

b. In a full documentation, Figs. 22 and 23 should be complemented 

to include: 

The number of surges at each location, city, and place. 

The following percentiles of the distribution: 1. 10. 25. 50. 75. 

90, 95, and 99 at each location, city, and place (and totals); or 

A frequency table for each location, city, and place (and totals). 

showing the number. or percentage, of surge within specified 

frequency-of-occurrences classes. 
3. 1 

11 

due 

ed I 

The mean and the standard deviation for each location, city, and 

place (and totals). 

for each of the following: time to peak current and voltage, time 

to 50% current and voltage, and peak voltage and current. 

Alternatively, some of this information can be provided by 

histograms, frequency curves, or both. 

The information on "min" and "max" is inadequate to give a good 

picture; for one thing, min and max depend upon sample size. Thus, 

the minimum complementary information to Figs. 22 and 23 should 

be the percentiles. 

Iijferentiation Between Types of Surges 

.would be most interesting to be able to differentiate between surges 

to lightning storms and power system switching surges, for jmprovunderstanding. We recognize that such information might not be 

available. ~oweier, if it is akilable, even on a sample basis, it warrants 

reporting. If it is not available, some insights might be provided by: 

Vertical: 40 Aldiv - Sweep: 0.J mrldir 

a. Breaking down Figs. 21 and 22 by city, as previously suggested. Fig. B. Current surge in a varistor, ralting from capacitor bankswitching 

In particular, Miami versus Seattle should be interesting as a possible 

discriminator for lightning. 

- Now, taking the mean of the 45 occurrences of front time shown 

in Table 11, which we compute at 2.00, and applying Student's "t 

Test" to compare this mean of 2.00 to the overall mean of 1.07, we find a statistically significant difference at the 0.1% level between the two means. This difference should not be significant if 

the sample is a random sample from the total population. Thus, 

the statement that the values of Table 11 make up a random siunpie needs clarification. vertical: 20 */dl* - Sweep: 0.2 uldlv 

Moreover, the value of 1.07 does not appear to be the median 

either, because only 8 of the 45 values aven in Fig. 21 are below 1-07. Fig. C, surge in a resulting from capclcitor b. The statement " '89.4% within * 10% envelope" is ambiguous. 

Questions 10: Does this statement refer to voltage or current? 

Time to crest or time to 50%? 

Peak value? 

All of the above (an amazing coincidence or an instrument artifact [see Question 2])? 

Figs. 21 and 22 complemented, or revised as suggestted, would provide 

more meaningful summary values. 

Conclusion 

The measurements reported in this paper surely represent a major commitment of resources by the authors' organization, which the community 

of workers in the field of surge characterization can well recognize and 

appreciate. The ultimate value of this effort would be substantially 

enhanced, and the ambiguities removed, if the authors could provide 

a response to the questions raised in the present discussion and to any 

others that might be submitted. 

Fig. D. Voltage at terminals of shorted load with parasitic inductance, 

during conduction of a current surge 

Fig. A. Voltage transient caused by capacitor bank switching Fig. E. Voltage at line terminals during application of a step function 
REFERENCES and then the computer analysis for the peak of the event 

and the first 50% point of that peak. Therefore, points (a). 

I] F. D. Martzloff, Varistor vs Environment: W~nning the Renratch. (b), and (c) would not be recorded (from Figs. A, B, and 

8SSM 365-2 IEEEIPES 1985. C); point (d) on graph (Fig. D) is unclear, and point (e) (Fig. E) would be recorded. 

IF. D. Martdoff is now associated with the Electrosystems Division of Yes, after the recording and analyzation of the transient 

k National Bureau of Standards, Gaithersburg, MD. event. there is a recovery time to ensure accurate data 

storage. If a second event occurs during the analyzation and 

recovery time, it would not be recorded. 

Manuscript received February 28. 1985 Question 8: This survey involved nine cities and seven locations. 

Does this statement mean that there were 7 locations in 

R, Odenkrg and B. J. Bmskich: To simplify the dialogue with the 

discusser and the reader of the Transactions document, the questions 

will be provided with the answers. 

Discussion from - F. D. Martzloff 

Comments to paragraphs on: 1. Waveform versus data points. 

2. Computer - drawn waveforms. 

It is the opinion of the authors that the discusser's comments regarding 

waveforms are inappropriate. It is our opinion that the technique utilized and the classification of the measurements as waveforms, are consisIrnt with .~~- the waveform format as utilized in ANSI/IEEE C62.41. In addition, since there is a disclaimer attached to Figs. 24 and 25, we will 

not remove them from the paper. 

Comments to paragraphs 3 and 4, titled, "Exclusively Linear Loads." 

Quote. "it seems unfortunate that the measurements did not include a 

period of time with a known surge diverter connected across the line." 

Amer: the purpose of this field study was to measure the uncontrolled 

rnvironment, not the characteristics of a known surge suppressor that 

could be determined in a laboratory. 

Question I: Do the authors intend to extend their measurements to include some with known diverters installed downstream from 

the instruments? 

Answer I: No, what would be measured under these parameters would 

be strictly transient remnant, which can be accomplished 

in the laboratory using the waveforms described in the paper. 

Question 2: Have the authors considered calling upon an independent 

laboratory. such as the National Bureau of Standards, to 

characterize the instrument? 

A~wer 2: No, during the calibration period for each analyzer, the frequency spectrum was analyzed to cover a broad band of 

frequencies; with a variety of standard laboratory test equipment. There were no effects within the tolerance provided 

on this nulling process to the signals. 

Question 3: If the voltage-current correlation is being decided according 

to the criterion "the time between a voltage surge and a current surge is less than 50p," is this decision based upon the 

reaching of the unstated threshold for each current and 

voltage signal? 

Answer 3: Yes. 

Question 4: However, what would be the response of the instrument to 

complex waveforms such as those of Figs. A, B, C, D, and 

E, shown below? 

Question 5: Would the instrument record points (a), (b), (c), (d), and 

(e), respectively, as 50% points on those waves or record 

a later 50% passage? 

Question 6: When triggered by a threshold, and busy recording the 50% 

passage, does the instrument have a recovery time before 

it can record a subsequent peak of the same event, and then 

will it cite only the highest point of the total event? 

Question 7: Does the instrument record an unconnected second event 

that occurs soon after the first? 

Answers to 4, 5, 

6, and 7: When triggered by the threshold, the whole event is recorded 

each of the 9 cities, or a total of 63 "places?" 

(Table I1 shows 45 combinations.) 

How were the locations in each city selected? 

Can these be regarded as a random sample? 

Answer 8: Yes, there was a total of 63 "places" analyzed. 

Many factors were taken into account in the location selection process to consider a random sampling. 

Yes, 63 locations can be regarded as random sampling, even 

though 63 locations is a small number to 630 or 6300 or 

63,000 locations. It is far greater than 6 or 1 location. 

The nine cities are: 

Boston Los Angeles 

Chicago Seattle 

St. Louis Atlanta 

Miami Houston 

Salt Lake City 

Question 9: Table 11 shows only 45 combinations. to give the reader 

the example of how the data were presented by the 

computer. 

Is there a standard definition of a surge? 

is it the same from one city, location, and place to the next? 

Answer 9: The analyzers were designed under general conditions; there 

was no set definition of a surge prior to the installation 

of these systems. 

Yes, it was the same from one city. location, and place 

to the next; as defined by the transient analyzer and its standardized calibration for all analyzers. 

Comments to: Summary of the Study Results 

Based on the uniformity of 89.4%. there is no need to do that. 

Question 10: The statement "89.4% within i 10% envelope" is 

ambiguous. 

Does this statement refer to voltage current? 

*Time to crest or time to 50%? 

Peak value? 

All of the above (an amazing coincidence or an instrument 

artifact (see Question 2)? 

Answer 10: Yes, all of the above. These numbers (89.4%) are not an 

instrument artifact based on the extensive calibration tests 

performed on each computer system. 

Discussion From - Peter Richman 

The Answer to Question 10 above should answer his concerns. 

Summary 

The authors appreciate the assistance and interest in the two discussers. 

Francois D. Martzloff and Peter Richman, in the questions they ask. 

The data provided in this paper measuring voltage and current surge 

characteristics for the same event, should provide new methods and values 

for surge Standards, both current and future. In addition, the requirements for longer wave (1 x 10001(sec, 60 x 1000@x) testing should 

enhance performance and reliability of surge suppressor products and 

techniques, and ensure more reliable operation of electronic equipment 

in the field. 

Manuscript received April IS. 1985