Reprinted, with permission, from IEEE Transactions on Industry Applications IA-22, July/August 1986 

First presented at IEEE ICPS, May 1985

Significance: 

Part 4 – Propagation and coupling of surges 

The propagation and attenuation of surges or high-frequency disturbances in power lines has been described in different 

terms by workers hailing from time-domain or frequency-domain schools of thought. Nature, of course, recognizes 

neither one in particular, and the phenomena are the same. This paper is an attempt at unification of the description, 

reporting measurements made on the same specimen by the two different techniques. 

Unidirectional pulses with duration ranging from 200 ns to 50 μs, and the 0.5-μs – 100-kHz ring wave were injected in 

a metal-enclosed line as well as a non-metallic jacketed line. Data are presented in graphical form for the continuousfrequency measurements and as typical oscillograms for the pulse measurements. 

From the time-domain surge measurements, it becomes apparent that long lines will attenuate single-shot impulses for 

very short duration (less than 1 μs), but no appreciable attenuation can be expected for longer pulses. An open-end line 

will produce the classical doubling effect when the line length is sufficient to contain the surge front. If the line if shorter 

than this value, reflections occur while the surge front is still rising, so that the doubling effect produces steps on the front 

but no doubling of the ultimate peak of this surge.
634 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULYIAUGUST 1986 

Surge and High-Frequency Propagation in 

Industrial Power Lines 

FRANCOIS D. MARTZLOFF, FELLOW, IEEE, AND HAROLD A. GAUPER, JR., SENIOR MEMBER, IEEE 

Abstract-Laboratory measurements were made on a three-conductor 

line, with or without steel conduit sheath (typical of single-phase 120/240-V 

systems), to determine the attenuation of surges and the response to 

steady excitation at frequencies in the range of 100 Hz-10 MHz. Line 

length ranged from 75 to 225 m. Impedance matching was maintained at 

the sending end, while at the receiving end various loads (matched or 

mismatched) were included. A nonlinear load was also used, illustrating 

the side effects of connecting a surge protective device at the end of the 

line. 

T HE PROPAGATION and attenuation of surges or 

high-frequency disturbances in power lines has been 

described in different terms by workers hailing from timedomain or frequency-domain schools of thought. Nature, of 

course, recognizes neither one in particular, and the phenomena are the same. This paper is an attempt at unification of the 

description, reporting measurements made on the same specimen by the two different techniques. In a second phase of this 

work, numerical methods would be applied to correlate and 

convert the data from one domain to the other. 

A typical industrial power line was deployed in the 

laboratory, consisting of three conductors in a steel conduit. 

The line was folded into a zig-zag arrangement to allow both 

ends and two intermediate points to be within short reach of 

the instruments. The parameters of a three-conductor nonmetallic jacket line were also examined. Pulses of different shapes 

and continuous swept-frequency signals were applied at one 

end of the line. Measurements of voltages or currents were 

made to characterize the propagation and attenuation (or 

enhancement) of the signals. 

From the measurement results, data are presented in 

graphical form for the continuous-frequency measurements 

and as typical oscillograms for the pulse measurements. 

Implications are discussed for application to typical situations. 

The line consisted of 225 m of 20-mm (314-in) steel conduit, 

arranged in a zig-zag configuration to bring the start, the end, 

Paper IPCSD 85-34, approved by the Power Systems Engineering 

Committee of the IEEE Industry Applications Society for presentation at the 

1985 Industrial and Commercial Power Systems Technical Conference, May 

13-16. Manuscript released for publication March 7, 1986. 

F. D. Martzloff was with the General Electric Company, Schenectady, NY. 

He is now with the Electrosysterns Division, National Bureau of Standards, 

Building B 162, Room 220, Gaithersburg, MD 20899. 

H. A. Gauper, Jr., was with the General Electric Company, Schenectady, 

NY. He is now at 826 Sanders Avenue, Scotia, NY 12302. 

IEEE Log Number 8608868. 

and two intermediate points at 75 m and 150 m close to each 

other, allowing connection of recording instruments without 

change of probe length. Three wires of 3.3 mm2 cross section 

(12 AWG) were pulled through the conduit, representing the 

line, neutral, and grounding conductors of a typical singlephase installation. In all measurements, the neutral and 

grounding conductors were bonded to the conduit at the 

sending end, representing a typical service entrance configuration. At the intermediate points and at the far (receiving) end, 

the neutral was not connected to the grounding conductor. At 

the receiving end, the grounding conductor was also bonded to 

the conduit. Limited measurements were also performed on a 

75-m-long line of nonmetallic three-wire conductor to investigate the differences between the "open line" configuration 

and the "quasi-coaxial" configuration of the conduit-enclosed 

line. 

Because the conduit-enclosed line is practically insensitive 

to its surroundings, it could be zig-zagged in a steel-walled 

room without undue effects. In contrast, the nonmetallic jacket 

line might be sensitive to the proximity of walls and, very 

likely, to its own adjacent turns if not stretched out in "free 

space." To evaluate the importance of this concern, measurements were made on the three-conductor wire left in its 

original coiled package (50-cm average diameter) before the 

line was stretched out in a long hairpin shape, with only the 

sending and receiving ends inside the building, the rest of the 

line being held at least 4 m away from the building and 

ground. In these measurements the grounding conductor and 

neutral conductor were bonded at the sending end. 

Surges and signals were generally injected and measured 

between the line conductor and the neutral conductor, across 

which the sensitive loads are expected to be connected. In the 

experiment concerned with connection effects at the line end, 

measurements were also made between the neutral and the 

grounding conductors at the end of the 75-m line, where 

various configurations of surge suppressors were installed. 

Surges were generated by a Velonex 350 or KeyTek 711 

generator, monitored by a Tektronix 7633 oscilloscope with 

two P6015 probes in differential mode, allowing measurements at the four access points of the line. For the fast 

repetitive pulses generated by the Velonex 350 generator, a 

trigger signal allowed synchronized sweep of the oscilloscope 

for all four measurements, so that propagation time would be 

displayed on the recordings. For single pulses generated with 

the KeyTek 71 1 generator, internal triggering of the oscilloscope in single-sweep storage mode provided the recording of 

the pulses. Continuous frequency measurements were per0093-9994/86/0700-0634$01 .OO @ 1986 IEEE 
MARTZLOFF AND GAUPER: SURGE AND HIGH-FREQUENCY PROPAGATION 

STEEL CONDUN 

Fig. 1. Recordings at sending and intermediate points and receiving end of line, terminated with matching impedance, for 200-11swide pulse. 

formed with a Hewlett-Packard system consisting of a Model 

8553A spectrum analyzer and a 8443A tracking generator. 

Four types of surges were injected into the line, with 

different waveforms: 

a 200-ns-wide unidirectional pulse, 

a 2-ps-wide unidirectional pulse, 

a 1.2150-ps surge, as described by [3], 

a 0.5-ps 100-kHz ring wave, as described by [3]. 

A. 200-ns Pulse 

Fig. 1 shows schematically the test line and a composite 

oscillogram of the voltages at the sending end, intermediate 

points, and receiving end. Note the impedance-matching 

network between the generator and the line, providing an 

optimum wavefonn for the generator output (200 0) and 

minimizing reflection of the surges returning from the line 

(100 Q). A 100-0 matching termination was connected at the 

receiving end for this recording. 

The attenuation of this pulse along the line is quite apparent, 

with an average 0.7 ratio between the voltages of points 

separated by 75 m of line. The propagation time for the 225 m 

can be seen as 1.1 ps. 

Fig. 2 shows the propagation of the same 200-ns-wide pulse 

with open-ended line. The voltage enhancement at the receiving end (3.75 divisions compared to the 1.9 divisions in Fig. 1) 

illustrates the classical doubling effect at the open end. In spite 

of this doubling effect, enough attenuation of the short spike 

occurs over the total 225 m of the line that the pulse at the 

receiving end is lower than that at the sending end. For a line 

length of 150 m, the doubling effect would result in a 

receiving-end crest of 2 x 2.5 = 5 divisions, i.e., equal to the 

sending-end pulse. For a line length of 75 m, the doubling 

effect would result in a receiving-end crest of 2 x 3.1 = 6.2 

divisions, i.e., a 20-percent enhancement of the sending-end 

pulse. Note also that, while the amplitudes are attenuated, the 

rise times tend to be increased, so that the volt-time integral of 

the pulse (and therefore its potential for damaging energysensitive components) is not attenuated as quickly as the 

amplitude. 

B. 2-p Pulse 

Fig. 3 shows the propagation characteristics of a 2-ps-wide 

pulse along the same line, with matched termination at the 

receiving end. For this slower pulse the attenuation is lower, 

with a ratio of 0.94 between the voltages of points separated by 

75 m of line. The change of slope, which was quite apparent 

for the 200-11s pulse, is hardly noticeable in this recording, the 

four pulse traces having essentially parallel rises and falls. 

This lesser distortion is easily explained by the lesser effect of 

the line shunt capacitance on the lower frequencies associated 

with the 2-ps-wide pulse. 

C. 1.2/50-ps Surge 

Fig. 4 shows the test circuit for surge tests with matched 

terminations. The R, series resistance at the sending end 

provides matching for the low-impedance (0.6 or 12 0) 

generator plug-in networks, and the R, terminating resistance 

at the receiving end eliminates reflections. 

Fig. 5 shows three recordings for the 75-m conduit line 

excited by a 1.2150-ps surge, with open end and with a 

matching termination at the receiving end. Fig. 5(a) shows the 
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULYIAUGUST 1986 

Fig. 2. Recordings at four points of line, open end, for 200-ns-wide pulse. Fig. 3. Recordings at four points of line, matched termination, for 2-pswide pulse. 

Rs Rt 

P.I. : 

71 1 

2 pi Rs Rt 

1.2/50,bnduit 0.6 100 100 

1.2/50,Non-metal I ic 0.6 125 125 

Ring Wave,condui t 12 50 100 

Fig. 4. Test circuit for recordings with 1.2150-as surge and with ring wave 

Fig. 5. Recordings on 75-m conduit line with 1.2150-ps surges. All oscillograms: vertical = 1 kvldiv, sweep = 500 nsldiv. (a) 

Open4rcuit voltage produced by generator. @) Voltage at sending end. Top: open at receiving end. Bottom: 100 Cl at receiving 

end. (c) Voltage at receiving end. Top: open at receiving end. Bottom: 100 fl at receiving end. 

open-circuit voltage delivered by the surge generator. Because 

a series resistor is present at the sending end, a 2: 1 voltage 

divider effect is produced at the sending end for the long-term 

voltages when a terminating resistor is connected at the 

receiving end. Therefore, the terminated-end trace (bottom) 

shows half of the voltage of the open-end trace (top). For the 

first 750 ns of the sweep, the reflection from the receiving end 

has not arrived, and, consequently, the two traces are identical. 

Fig. 5(c) shows the voltages at the receiving end, with and 

without termination. Observe that the long-term voltages 

match the sending-end voltages of Fig. 5(b). Only the rising 

part of the top trace of Fig. 5(c), for the first 1500 ns, shows a 

doubling of the voltage applied at the sending end, but this 

doubling would not change the stress at the receiving end, 

except for the steeper rate of rise. 

The behavior of the nonmetallic (stretched) 75-m line shown 

in Fig. 6 is similar to that of the conduit line, but the traces are 

not quite as smooth. From the differences in high-frequency 

response of the conduit and nonmetallic line shown by the 

continuous-frequency measurements discussed later, these 

irregularities in the nonmetallic line can be expected. 

D. 0.5-ps 100-kHz Ring Wave 

Fig. 7 shows the recordings for the 75-m conduit line 

excited by a ring wave, with open end and with matched 

termination. The voltages at the sending end (Fig. 7(a) and (c)) 

(a) (b) 

Fig. 6. Recordings on 75-m nonmetallic stretched line with 1.2150-ps 

surges. Vertical: 1 kV1div. Sweep: 500 nsldiv. (a) Voltages at sending end. 

Top: open at receiving end. Bottom: 125 Q at receiving end. (b) Voltages at 

receiving end. Top: open at receiving end. Bottom: 125 flat receiving end. 

differ by the reflection during the first loop, producing the 

double peak in Fig. 5(a). Furthermore, the voltage divider 

effect of the series resistance also lowers the sending-end 

voltage when a terminating resistor is connected at the 

receiving end. At the receiving end the difference between an 

open or terminated condition is apparent. 

1) With a matched termination, the receiving-end voltage of 

the first loop is 2.5 kV for a 3-kV sending-end voltage, 

indicating attenuation of the high frequencies as previously 

noted in the case of the 200-11s pulse. Later loops show less 

attenuation. 

2) With an open end the reflection effect is less than 
MARTZLOFF AND GAUPER: SURGE AND HIGH-FREQUENCY PROPAGATION 

Fig. 7. Recordings on 75-m conduit line with 0.5-ps 100-kHz ring wave. All 

oscillograms: vertical = 1 kvldiv, sweep = 2 psidiv. (a) Voltage at 

sending end, line open at receiving end. (b) Voltage at receiving end, line 

open at receiving end. (c) Voltage at sending end, 100-Q termination at 

receiving end. (d) Voltage at receiving end, 100-0 termination at receiving 

end. 

doubling-5 kV against 3 kV-as the result of the highfrequency attenuation and again little attenuation in later 

loops. 

Two types of frequency domain measurements were performed over the frequency range of 100 Hz-10 MHz with the 

spectrum analyzer and tracking generator. 

1) The input impedance versus frequency of the line was 

determined by measuring the voltage applied to the line 

and then the current drawn by the line. 

2) The transfer ratio of the line versus frequency was 

determined by measuring the voltage applied to the line 

and the voltage at the far end of the line. 

To assure adequate decoupling of the tracking signal 

generator output, a resistive pad was connected to the output. 

This pad consisted of a 47.5-Q resistor in series with a 2.54 

resistor to a coaxial shield ground. The test line was thus 

driven by the 2.54 source. All data were recorded with an 

X-Y recorder, and then calculations were made to establish 

the reported data. 

The transfer ratio measurements required ungrounded 

instrumentation in order to eliminate ground loops and the 

influence of undesired grounding at the remote end of the test 

line. Therefore, a relatively high resistance of a 7500-i'l 

noninductive resistor was connected at the remote end of the 

test line and a Genistron current transformer was used to 

measure the current flowing in the resistor, thus establishing 

the voltage at the quasi-open-ended line. The voltage at the 

sending end was obtained through a Hewlett-Packard 1121A 

ac voltage probe. 

Fig. 8 illustrates the input impedance of the conduit line 

under this type of excitation. The two curves labeled 275 and 

MHz 

Fig. 8. Impedance of 225- and 75-m tines and VJV, ratio of 75-m line as 

function of frequency. 

2225 show the impedance of the line seen from the sending 

end when a 100-Q matching resistance is connected at the 

receiving end, as a function of the frequency of the applied 

signal. 

Referring to the 2225 curve, the behavior of this 225-m line 

shows the standing wave effects at 114, 112, 314, and 1 

wavelength. At 0.2 and 0.6 MHz the line impedance is low, 

typical of 114 and 314 wavelengths, while it is high at 0.4 and 

0.8 MHz, typical of half and full wavelengths. For the 0.8- 

MHz frequency, the period is 1.25 ps; with a line length equal 

to one full wavelength, the speed of propagation determined 

by this measurement is 225 ml1.25 ps = 180 dps, which is 

close to the result obtained by the pulse propagation time of 

1.1 ps shown in Fig. 1, i.e., 225 m1l.l ps = 204 mlps. The 

difference between these two results is well within the limits of 

calibration and reading of the different instruments used for 

the measurements. 

Referring to the 275 curve of Fig. 8, the first low point 

occurs at three times the frequency of the first low on the 2225 

curve, which is consistent with the 1:3 ratio of line length. 

Note also that this shorter line involves a lower total 

resistance; hence the IN-wave resonance effect is larger than 

the 314-wave resonance. This resonance is quite apparent on 

the VJV, 75 curve, which shows the ratio of the voltages at 

the receiving end to the sending end, with a quasi-open (7500 

0) receiving end. 

Fig. 9 is a plot of the input impedance versus frequency of 

three configurations of open-ended 75-m lines: the conduitencased line, the nonmetallic coiled line, and the nonmetallic 

stretched line. The differences of input impedance for the 

three configurations should come as no surprise. The conduit 

line appears well controlled, with more damping that the 
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULYIAUGUST 1986 

IMPEDANCE 1 1 I I I I 1 I I I I 

- 

- 

NON-MET STRETCH 

NON-MET COILED 0 1 I 

0 2 4 6 8 10 

FREQUENCY, MHz 

Fig. 9. Input impedance for open-ended 75-m lines. 

0 2 4 6 8 10 

FREQUENCY, MHz 

Fig. 10. Ratio of receivinglsending voltages for open-end nonmetallic 75-m line, coiled and stretched. 

nonmetallic line of amplitude between the 114-wave minima 

and 112-wave maxima of the lines. The simple response of the 

conduit line is also apparent, compared to the parasitic effects 

that appeared in the coiled configuration. 

Fig. 10 shows a comparison between coiled line and 

stretched line for the ratio between sending-end and receiving-end voltages. The voltage multiplication seen at the far end 

at about 0.6 MHz agrees with the Vo/K 75 curve of Fig. 8 for 

the 114-wavelength condition. Both stretched and coiled lines 

show a multiplication of about 24 dB (15 times) with little 

difference between the responses. The second peak begins to 

show some shift between the two lines, and the differences 

increase at higher frequencies, showing the need to stretch out 

the line for obtaining results free from the parasitic effects of 

the coiled configuration. The ratio drops to a minimum of 5-6 

dB rather than zero (no voltage enhancement) because the 

measurement system used had a noise background which 

precluded recording of any lower current measurements at the 

receiving end. 

Fig. 11, reproduced from [I], shows an earlier measurement of line impedance in the low-frequency region made with 

a Hewlett-Packard Model 4800A vector impedance meter, 

with the line shorted at the far (receiving) end, which is the 

converse situation of the measurements reported here, where 

the voltages at the receiving end are recorded with the line in 

quasi-open condition. 

RELATIONS BETWEEN IMPULSE AND CONTINUOUS WAVE 

MEASUREMENTS 

The time-domain impulse measurements illustrate directly 

the propagation of a surge of the type encountered in actual 

i 

00 

kHz 

Fig. 11. Input impedance of 75-m line, nonmetallic type, with shorted 

receiving end. 

power systems. The effects of an open end, or a high 

impedance at the far end, are quite apparent. 

The frequency-domain measurements indicate the importance of standing wave effects for specific frequencies, which 

may be frequencies of low-level communication carriers or the 

frequency of a particular point of the transform spectrum of a 

single impulse. To predict performance of a particular 

configuration, it may then be possible to model the line, which 

would then become a simple case of conventional network 

analyses by numerical methods [2]. On the other hand, setting 

up a real line or network of lines may be cumbersome but 
MARTZLQFF AND GAUPER: SURGE AND HIGH-FREQUENCY PROPAGATION 

yields immediate results, such as those illustrated in the next 

section on the effect of connecting surge suppressors at the end 

of the line. 

Comparisons of impulse measurements sometimes give 

considerable emphasis to crest values, neglecting the effect on 

waveform, as noted in connection with Fig. 2. A continuousfrequency spectrum, however, will readily identify the 

change. 

With the advent of increasingly sophisticated electronic 

devices, a proliferation of add-on surge suppressors has been 

offered for insertion at the point of use of these devices, that 

is, at the receptacle located at the end of a line, such as those 

discussed in the preceding sections. The actual configuration 

of these suppressors is generally not disclosed, but they may 

be classified into three categories, for the case of a singlephase two- or three-wire power supply. A first category 

involves only one protective device, which may be connected 

line-to-neutral or line-to-ground. A second category would 

involve two devices, and the third, three devices. The 

differences among these three categories is shown in [I]; 

however, ring-wave surges [3] may present a more insidious 

situation than the unidirectional surges used in [I]. The 

insidious nature of the effect is associated with the inductive 

characteristics of the line discussed here, when carrying fastrising surge currents associated with the presence of a surge 

suppressor at the end of the line. 

Fig. 12 shows four possible combinations of protective 

devices that may be connected at the user's end of a branch 

circuit when the user has no control on what protection could 

be added at the service entrance. Fig. 12(a) shows a single 

protective device connected between the line and neutral 

conductors, under the perception that this is the location of the 

most sensitive components of the connected load (L). Fig. 

12(b) shows again a single device, connected between the line 

and grounding conductors, under the perception that the surge 

current should be returned to "ground." Fig. 12(c) shows two 

devices, one between line and neutral conductors, the second 

between neutral and grounding conductors. Fig. 12(d) shows 

three protective devices. The effects of various comections 

when a slow-front current is involved were described in [I]. 

With faster surges, while lower energies are involved, 

ironically, a greater voltage spike is produced, as revealed by 

Fig. 13. 

Fig. 13 shows the result of connecting a surge suppressor 

device that provided clamping only between the line and 

neutral conductors, as shown in Fig. 12(a). Fig. 13(a) shows 

the voltage set at a peak of 3 kV at the sending end of the line. 

With that setting of the generator, the current in the line is 

shown in Fig. 13(b). The generator is capable of delivering 6 

kV open-circuit and 500-A short-circuit. The load-dependence 

of this type of circuit is evident in Fig. 13(b) where the current 

peak is limited to 40 A. Fig. 13(c) shows the voltage between 

line and neutral which, predictably, is correctly clamped at 

about 400 V. However, the voltage between neutral and 

grounding conductors (Fig. 13(d)) reaches a peak of 2300 V 

during the initial current rise and 1300 V during the fall of the 

: NeutreiConductor BondedTopaLer.ItheSendinp End 

G : Grounding Conductor 1 (Service Entrance) 

(L) : Load to be Protected 

Fig. 12. Connection options for protective devices at end of branch circuit. 

Fig. 13. Effect of connecting single surge suppressor between line and 

neutral at end of 75-m line, with neutral and grounding conductor bonded at 

origin of line. (a) Voltage at sending end while line is carrying current of 

Fig. 12(b). Vertical: 1 kVidiv. Sweep: 2 psldiv. (b) Current in line with 

ring-wave surge generator excitation. Vertical: 20 Aldiv. Sweep: 2 psldiv. 

(c) Voltage between line and neutral with surge current of Fig. 12(b). 

Vertical: 500 Vidiv. Sweep: 2 psidiv. (d) Voltage between neutral and 

grounding conductor with surge current of Fig. 12(b). Vertical: 500 Vldiv. 

Sweep: 2 psldiv. 

current at the end of the first loop. The correspondence 

between peaks of voltage during fast current change and zero 

voltage during peaks of current is quite apparent in a 

comparison of Fig. 13(b) and (d). This correspondence is 

attributable to the inductive voltage drop in the neutral 

conductor, which elevates the neutral terminal of the line-end 

receptacle with respect to the grounding terminal. The 

grounding terminal remains at the potential of the ground at 

the sending end. 

A load connected at the receptacle and "protected" by the 

single device will then be exposed to substantial peaks of 

voltage between its neutral and chassis, if any. Because of the 

expectation that neutral and grounding conductors should not 
640 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO 4, JULYIAUGUST 1986 

Fig. 14. Effect of connecting suppressor having clamping devices between 

both line-neutral and neutral-ground pairs, at end of same line and same 

applied surge as in Fig. 13. (a) Voltage between l~ne and neutral with surge 

current of Fig. 13. (b) Voltage between neutral and grounding conductor 

with surge current of Fig. 13. 

drift far apart in voltage, being bonded at the service entrance, 

the designer of the load equipment might not have provided for 

this 2300-V peak in the insulation between neutral and chassis. 

If the function of the equipment can be disturbed by fast 

voltage changes, there is also a good probability that disturbances may occur. Thus what was intended to be a simple 

protective scheme can result in unwanted and unexpected 

probiems. 

An effect similar to that shown in Fig. 13 would be obtained 

for the connection of Fig. 12(b), but with the 400-V clamping 

voltage occurring between line and grounding conductors and 

the uncontrolled voltage of 2300 V produced between line and 

neutral conductors, placing any components connected across 

the line in severe jeopardy. 

In contrast, the performance of a surge suppressor that 

provides clamping between line and neutral and between 

neutral and grounding conductors is shown in Fig. 14, for the 

same surge-injection conditions as those of Fig. 13(a) and (b). 

Both voltages are clamped below 400 V, and while the initial 

rates of voltage changes are not affected by the clamping 

action, the total excursion is limited. Clearly, this mode of 

protection with added clamping between neutral and grounding conductors offers a substantial improvement over the case 

of Fig. 12(a). ' Further protection of equipment sensitive to 

fast voltage changes may be obtained by insertion of a filter 

that will decrease the rate of voltage changes shown in Fig. 14. 

The data obtained by these measurements should be a source 

of useful information for the application of preventive measures for equipment connected at the end of lines, such as 

those reported here. 

1) From the time-domain surge measurements, it becomes 

' This improvement is obtained from the point of view of equipment 

protection, where a surge of 1-ps duration as seen in Fig. 13(d) can cause 

failure. The National Electrical Code, In Sectlon 280-22, specifically permits 

the connection of a surge arrester between any two conductors of a three-wire 

single-phase system. However, with the surge current now returning to the 

service entrance by the parallel combination of the neutral conductor and the 

grounding conductor, a brief surge will appear between the equipment chassis 

connected to the grounding conductor and other local grounded structures, 

unless a bond is installed at that point to bridge the chassis and the other local 

grounded structures. The occurrence of this brief aurge would be lmited to the 

duration of high rates of current change, but its implication on personnel safety 

has not yet, to our knowledge, been evaluated In this context. 

apparent that long lines will attenuate single-shot impulses of 

very short duration (less than I ps), but no appreciable 

attenuation can be expected for longer pulses. 

2) An open-end line (e.g., a line feeding a low-power 

control circuit) will produce the classical doubling effect when 

the line length is sufficient to contain the surge front. If the line 

if shorter than this value, reflections occur while the surge 

front is still rising, so that the doubling effect produces steps 

on the front but no doubling of the ultimate peak of this surge. 

3) While conduit-enclosed lines may be folded for convenience in making indoor testing, nonmetallic lines need to be 

stretched away from surrounding conductors to obtain valid 

results at high frequencies. 

4) Connecting surge protective devices at the end of a line is 

a typical action undertaken by prudent users; however, unless 

the behavior of the circuit is well understood, simple protective schemes can backfire unless adequate connections are 

provided. 

\I] F. D. Martzloff, "The propagation and attenuation of surge voltage and 

surge currents in low-voltage ac power circuits," IEEE Trans. Power 

App. Sysl., vol. PAS-102, pp. 1163-1170, May 1983. 

121 H. W. Dommel , "D~gital computer solution of electromagnetic 

transients in single and multiphase networks," IEEE Trons. Power 

App. Syst., vol. PAS-88, pp. 388-399, Apr. 1969. 

131 IEEE Guide for Surge Vohges in Low-Voltage AC Power 

Circuits, ANSIIIEEE Standard C62.41, 1980. 

Fran~ois D. Martzloff (M'56-SM'80-F'83) was 

born in Strasbourg, France, on June 9, 1929. He 

received the degree from Ecole Speciale de Mecanique et d'Electricitt, the M.S.E.E. degree from the 

Georgia Institute of Technology, Atlanta, and the 

M.S.1 A. degree from Union College, Schenectady, 

NY, in 1951, 1952, and 1971, respectively. 

He was with the General Electric Company for 

many years, working on transient measurements, 

surge protection of electronics, and applications of 

varistors. He is presently with the National Bureau 

of Standards, Gaithersburg, MD, focusing on conducted electromagnetic 

interference. 

Mr. Manzloff has received numerous Awards and he is active in writing 

standards with the IEEE, IEC, and ANSI. 

Harold A. Gauper, Jr. (M'49-SM'55) received 

the B.S. degree in electrical engineering from the 

University of Wisconsin, Madison, in 1943. 

He joined the General Electric Company shortly 

after graduation. Since his assignment to the field of 

Electromagnetic Compatibility in 1950, he has 

continued to specialize in the development of 

measurement methods, prediction and control of 

EMI, NEMP, and immunity associated with a broad 

range of consumer, industrial, electrical power, and 

mllitary products and programs. He holds three 

patents on EMC-related control techniques. Among his assignments for many 

years was the responsibility to represent the General Electric Company 

interests in EMIIEMC technical standards and regulations. As a result he was, 

and continues to be, involved with Federal Communications Commission 

rulemaking with regard to Pan I8 (ISM Equipment) and Part 15 (Radio 

Frequency Devices). He was Chairman of the NEMA Electromagnetic 

Compatibility Committee and actlve in the EMC standards work of ANSI 

C63, IEEE EMC Society, and other IEEE standards committees, as well as 

the IEC-CISPR and TC-77. He continues to be involved in lEEE EMC 

standards matters since h~s recent retirement from the General Electric 

Company. 

Mr. Gauper has served on the lEEE EMC Society Board of Directors, most 

recently in 1978-1981, and served as a Charter Member of the Federal 

Electromagnetic Radiation Management Advisory Council which advised on 

RF biohazard matters.