end-user power systems by a single number – the "energy in the surge" – derived from a simple voltage 

measurement. Numerical examples illustrate the fallacy of this concept. Examples are given of 

equipment for which a failure can be caused by a surge voltage, but with or without relationship to the 

energy involved in the process. 

Furthermore, based on the proliferation of surge-protective devices in low-voltage end-user installations, 

the paper draws attention to the need for changing focus from surge voltage measurements to surge 

current measurements. This subject was addressed in several other papers presented on both sides of 

the Atlantic (See in Part 5 “Keeping up”-1995; Make sense”-1996; Joules Yes-No-1997; “Novel 

transducer”-2000; and “Galore”-1999 in Part 2), in persistent but unsuccessful attempts to persuade 

manufacturers and users of power quality monitors, and standards-developing groups concerned with 

power quality measurements to address the fallacy of continuing to monitor surge voltages in post-1980 

power distribution systems As it turned out, the response has been polite interest but no decisive action.
Paper presented at the 7 International Conferem 

on Harmonics and Quality of Power 

Les Vegas, October 1818, 1996 

No Joules for Surges: 

Relevant and Realistic Assessment of Surge Stress Threats 

Thomas Key and Arshad Mansoor 

Power ~lectknics Applications Center 

Knoxville, TN 37932 USA 

Absftclcl: The paper challenges attempts to characterize the surge 

environment in low-voltage end-users power systems by a single 

number - the "energy in the surge" - derived from a simple 

voltage measurement. Our thesis is that such attempts are neither 

realistic nor relevant The paper shows that these erroneous 

attempts, based on the classical formula for computing the energy 

dissipated in a linear load of known resistance, cannot be applied 

to characterize the environment per se, but only to a welldefined 

combination of source and load. In particular, there is no 

meaningful relationship between the 'energy" in a surge event and 

the energy actually deposited in a varistor by this surge event. A 

review of equipment failure or upset mechanisms related to the 

occurrence of a surge voltage reveals that none of these mechanisms 

are related to this so-called "energy in the surge." Several failure 

mechanisms other than energy-related an identified, pointing out 

the need to describe the surge events with a more comprehensive 

set of parameters in conducting future surveys. 

In an attempt to characterize the potential threat of surges to 

voltage-sensitive equipment, recordings of the surge voltages 

occuning in low-voltage power circuits have been conducted in 

the last quarter-century, driven by the increasing concern about 

the vulnerability of new electronic appliances to transient overvoltages. However, practically all the recording conducted by 

organizations such as Bell Laboratories [I], Canadian Electrical 

Association [2], General Electric [3], IBM 141, National Power 

Laboratory [5] and other researchers, including Goedbloed [6], 

Hassler & Lagadec [q, Meissen [S], and Standler [9] have been 

limited to thimeasurements of transient voltages 

Interest in these measurements has been re-kindled by 

several investigations aimed at assessing power quality in enduser facilities. These recordings, initially limited to 

measurement of peak voltages, were perfected with the help of 

increasingly sophisticated voltmeters. 

Early surveys were conducted with conventional 

oscilloscopes and later on, portable digital instruments with onboard computing became available. While these instruments 

made possible the recording of a voltage transient as a function 

of time and graphical presentation of data, the recording of such 

a surge voltage profile does not lend itself to a simple 

description by a single number. To circumvent this difikulty, 

many researchers called upon the basic concept of energy to 

characterize the level of surge threat in terms of voltage. 

Referring now to classical electrical engineering, the 

instantaneous power dissipated in a resistor by a transient 

voltage is merely the square of the applied voltage, divided by 

the resistance. 

Franqois Martzloff 

National Institute of Standards and Technology * 

Gaithersburg, MD 20899 USA 

Taking the integral over the duration of the transient yields the 

energy. By analogy, the "energy" of a surge could then be 

computed fiom the voltage measured at some point of a power 

system. According to this intuitive concept -- but fallacious as 

we will show - the greater the measured voltage, the greater 

the "energy" and thus the greater the threat to potential victim 

equipment. 

A review of the known failure or upset mechanisms of 

various types of devices and equipment identifies several surge 

parameters other than energy-related. These include source 

impedance, peak amplitude, maximum rate of rise, tail duration, 

and repetition rate. Therefore, future surveys of surge events 

conducted with present monitoring instruments or with even 

better instruments will need to include more comprehensive -- 

and hopefully standardized methods of presenting and 

interpreting the results. 

11. THESIS 

Our thesis is that neither the threat nor the "energy level" of 

a surge can be characterized by simply measuring the voltage 

change during a surge event. Any reference to the concept of 

"energy of a surge" should defdtely not be introduced. Such 

avoidance is based on two facts: 

1. A voltage measurement of the surge event cannot alone 

predict the energy levels affecting the devices exposed to 

that surge. This is particularly true for nonlinear surgeprotective devices where energy deposited in the device is 

relevant, but has little to do with the misleading concept of 

"energy in the surge" derived from an open-circuit voltage 

measurement. 

2. There are other than energy-related upset or failure modes 

of equipment. These effects require consideration of other 

parameters when describing a surge event to yield relevant 

and realistic assessment of surge stress threats. 

Our thesis will be supported by an analysis of the impact of 

surges on equipment, and illustrated by numerical examples of 

varistor applications showing how the description of a surge by 

its "energy" could then lead to vastly different wnclusions. 

ILL INTERACTIONS BETWEEN SURGES AND MCLlM EQUPMENT 

At this point, we need to identify the devices and equipment 

that may become the victims of a surge, and their failure 

mechanisms. After-the-fact investigations and experimental 

data show a wide range of surge-related upset and failure 

mechanisms. 

EIectricity Division, Electronics and Electrical Engineering Laboratory, Technology Administration, US. Department of Commerce. 

Contribuiionsfiom the National Institute of Standarh and Technology are not subject to US. Copyright. 
These mechanisms include insulation breakdown, flashover, 

hcture, thermal and instantaneous peak power overloads, dv/dt 

and didt limits being exceeded. The following list gives some 

generic types of surge victims and the typical failure or upset 

mechanisms. 

I. Electrical insulation, where the failure mechanism 

(breakdown or sparkover) is principally a function of the surge 

voltage, with the complication of a volt-time characteristic such 

that failure under impulse occurs at a level that increases when 

the rise time or duration of the impulse decreases. "Insulation" 

is to be taken in the broadest sense of solid or liquid material 

separating energized conductors in equipment, clearances on a 

printed circuit board, edges of semiconductor layers, etc. A 

distinction must be made between the initial breakdown of 

insulation, related to voltage only, and the final appearance of 

the damaged insulation, related to the total energy dissipated in 

the breakdown path. In another situation, the insulation of the 

frst tums of a winding may be subjected to higher stress than 

the others as the result of the uneven voltage distribution 

resulting from a steep front rather than only the peak value of 

the surge. 

2. Surge-protective devices, for which the voltage across the 

device is essentially constant, and the energy deposited is a 

function of the surge current level and duration. One failure 

mode of such a device will occur when the energy deposited in 

the bulk material raises the temperature above some critical 

level. Failure modes associated with the current level, such as 

flashover on the sides of a varistor disc, failure at the boundary 

layers of the varistor grains, or fracture of large discs, have also 

been identified and are not related to energy. 

3. Semiconductor devices, such as thyristors responding to the 

rate of voltage change can be turned on by a surge [lo], 

resulting in failure of the device or hazardous energizing of the 

load they control. In a similar way, a triac may be turned on by 

a voltage surge without damage, but still fail by exceeding the 

peak power limit during a surge-induced turn-on with slow 

transition time. 

4. Power conversion equipment, with a fiont-end dc link where 

the fiter-capacitor voltage can be boosted by a surge, resulting 

in premature or unnecessary tripping of the downstream inverter 

by on-board overvoltage or overcurrent protection schemes. 

5. Data-processing equipment, where malfunction (data 

errors) -- not damage -- may be caused by fast rate of voltage 

changes (capacitive coupling) or fast rate of current changes 

(inductive coupling) that reflect the initial characteristic of the 

surge event. This response is insensitive to the "tail" of the 

surge, where all the "energy" would be contained according to 

the misleading energy-related concept. 

6. Light bulbs, which of course have a llmlted life associated 

with filament evaporation and embrittlement -- a long-term 

process where the short burst of additional heating caused by a 

few microseconds of overcurrent is negligible -- but also fail 

under surge conditions when a flashover occurs within the bulb, 

triggering a power-frequency arc that melts out the filament at 

its point of attachment -- another failure mechanism originating 

with insulation breakdown. 

Among these types of victims, only the clamping-type 

varistor, exemplified by the metal-oxide varistors that became 

so prevalent after their introduction in the mid-seventies, is 

directly sensitive to an energy level associated with a surge 

event -- and at that, the energy deposited in the devic;, not the 

"energy in the surge." (To be absolutely correct, the ultimate 

failure mode of a triac or a light bulb may be indirectly 

influenced by the energy dissipated in the device during the 

surge, but the root cause, the trigger, of the failure is not the 

energy.) Considering the explosive proliferation of varistors, 

however, one might find some extenuating circum-stances in 

emphasizing the significance of energy in describing the effect 

of surges on its principal target -- the ubiquitous metal-oxide 

varistor -- but this is a pitfall, a mental trap. 

N. BAITING THE TRAP 

From the interactions described above, it is clear that using 

a single voltage measurement to determine surge threat is not 

sufficient. The trap was baited by the simplicity and ease of 

using a single parameter obtained by analogy with the power 

dissipated in a fxed resistance, v2LR by an instantaneous 

voltage, v. Clearly in that limited case, the total energy involved 

over the surge event would be the time integral of Jbt, 

expressed by a number having the same dimensions as wattseconds, or joules in the SI system. And thus some power 

quality monitors placed on the market in the early eighties were 

printing out surge event characterizations expressed in joules. 

This "joule" number was obtained by computation of the 

/9Adt, where the voltage v was measured by the instrument, 

divided by a resistance (taken arbitrarily as 50 a), and 

integrated over the duration of the event. Manufacturers of 

power quality monitor soon recognized the potentially 

misleading aspects of such reporting and discontinued the 

practice 

Nevertheless, some researchers continued the practice and 

are to thii day attempting to characterize the surge environment 

by the single parameter of "energy in the surge." As a half-way 

measure, some are now proposing a new parameter "specific 

energy" to be understood as the integral of voltage-squared 

divided by a reference resistance of 50 Q (why that particular 

value ?) and they would report results in watt-seconds. Figure 1 

shows an example of this type of reporting [l 11. 

w [mws] ._ 

Figure 1 - Example of report of survey result [l 11 with number 

of occurrences as a function of "energy" in milliwatts-seconds 
Acknowledging that indeed, the selection of an appropriate 

varistor should reflect the level of threat to which it will be 

exposed, there is a need to characterize the threat in terms of the 

energy that will be deposited in the varistor by a specific surge 

event. However, there is no way that a voltmeter measurement 

only, even if it includes time, can provide that infonnatioa 

V. THESIS DEMONSTRATION BY VARISTOR APPLICATIONS 

To demonstrate our thesis by the ad absurdurn process, we 

will compute the "energy in the surge" as defined by the trapbaiting definition of "specific energy" for three surge events 

such that all have the same "specific energy" but different 

voltage levels, waveforms, and durations. Then, making a 

further assumption for the unknown impedance of the surge 

source, we will compute the energy actually dissipated in the 

varistor for these different voltage levels, waveforms, and 

durations, and observe that the resulting deposited energy is not 

the same ! 

I. Elementary example: basic calculation, fmd impedance 

As a fmt easy-to-follow step, we take three rectangular 

pulses, all selected to have the same "specific energy" but 

different voltage levels and corresponding durations, and compute the energy deposited in a (nonlinear) varistor having a 

given maximum limiting voltage, assuming that the source of 

the surge is a voltage source with some arbitrary, f~ed 

impedance. 

It is noteworthy that some source impedance has lo be 

presumed, because the varistor clamping action rests on the 

voltage divider effect of the source impedance and the dynamic 

varistor impedance prevailing for the resulting current. 

Start with an assumed surge measurement of 1000 V with 

duration of 50 ps. The specific energy of such a surge event, 

according to the proposed definition, is: 

(1000 V)2 x 50 ps / 50 Q = 1 joule. 

Now consider a surge with amplitude of 3 16 V (1000 / J10) 

and duration of 500 ps (50 x 10). Its specific energy, is: 

(316 V)' x 500 ps / 50 Q = 1 joule. 

To complete the bracketing range, consider a surge of 

3160 V (1000 x do), and a duration of 5 ps (50 / 10). Its 

specific energy is: 

(3160 V)' x 5 ps 150 B = 1 joule. 

We now apply each of the three voltage surges to a 130-V 

rated varistor (200 V at 1 mA dc), assuming an arbitrary source 

impedance of Zs = 1 8. One can compute the resulting current 

or, for this simple example, make a fast-converging manual 

iteration without the help of a computer, as follows: 

(a) assume a current I, and look up the resulting voltage Vv 

on the varistor I-V characteristic; 

(b) compute [Z, x 4; 

Ois[ZsxI]+ Vv=lOOOV? 

(d) If yes, I is correct, the energy deposited in the varistor is 

If no, go back to (a) with a converging assumption for I. 

Table 1 shows the results fiom this manual iteration for the 

three surges defined above. It is quite apparent that the constant 

"specific energy" for the three surges does not result in the 

same energy deposition. The dynamic impedance (VvlZ) of the 

varistor is also shown, to illustrate the well-known theorem that 

the power dissipated in a resistive load reaches a maximum for 

matched source-load impedance. This theorem is yet another 

reason why a surge to be applied to a varistor cannot be 

characterized in the abstract: one needs to know the source 

impedance (real and imaginary components) as well, to assess 

the energy sharing between source and load. 

2. Calculation with changing the surge source impedance 

As the next step toward reality, we repeat the manual 

computations for different values of the impedance of the 

voltage source, still for the same "measured specific energy" 

and for the case of the 1000 V rectangular pulse. Somewhat 

arbitrarily, but no more arbitrary than the 50-P value used in the 

definition of "specific energy", we select three values of the 

source impedance. 

Bear in mind that the reported measurements of surge 

voltages have never provided any information on the system 

source impedance to be associated with the reported surge. As 

a further oversimplification (an unjustified step in the real 

world), we will accept the assumption implied in the 

computation of the "specific energy" that this impedance has 

only real components, or is a characteristic impedance. Three 

values are used in the following examples. 

TABLE 1 

ENERGY DEPOSITED IN A VARISTOR BY A SURGE, AS A FUNCTION OF SURGE PARAMETERS, 

ALL SURGES HAVING A 1 JOULE "SPECIFIC ENERGY' FOR A SOURCE IMPEDANCE OF 1 OHM 

Rectangular Surge Parameters 

Postulated 

amplitude 

(v) 

3 16 

1000 

3160 

SourceNaristor Response to Surge 

Varistor 

current 

(A) 

20 

630 

2700 

Postulated 

duration 

(PSI 

500 

50 

5 

Computed 

"specific 

energy" (J) 

1 

1 

1 

Varistor 

voltage 

(v) 

296 

3 70 

460 

Varistor 

impedance 

(0) 

15 

0.59 

0.17 

Power in 

varistor 

(w) 

5920 

233 000 

1 242 000 

Energy in 

varistor 

(J) 

2.96 

11.65 

6.21 
50 to go along with the proposed definition of "specific 

energy" (high-frequency measurements are often made in 

a 50-8 environment and may be the reason for the value 

selected in the proposed definition). 

2 4 the so-called effective impedance of a Combination 

Wave generator, which is "deemed to represent the 

environment" as stated in the ANSIAEEE Recommended 

Practice C62.41-1991 [12]; 

400 4 a number sometimes cited as the characteristic 

impedance of an overhead line. 

Again here, a simple manual iteration yields the result by 

a varistor current, looking up the corresponding 

voltage on the I-V curve, such that this voltage is equal to the 

driving surge voltage, reduced by the voltage drop in the source 

for the postulated current. Table 2 shows the results for the 

three examples of assumed source impedance and a 130-V 

rated varistor. 

3. Computer cdculatwn with multiple combinations 

We now compute the energy deposited in three varistors 

of three different maximum limiting voltages, for three 

combinations of voltage levels and durations that produce the 

same "specific energy," each with classical waveform (Ring 

Wave, Combination Wave, Long Wave), sized to produce 

1 joule of energy dissipation in a 50-8 resistor, according to 

the classical formula cited earlier, and for three values of 

source impedance. We can anticipate that the peaks will be 

quite different, foreboding very different effects on equipment. 

In fact, the peaks turned out to be 3 kV, 1.2 kV, and 220 V 

respectively for the three waveforms. Applying these three 

waveforms to a family of varistors typically used in 120-V or 

240-V power systems, we computed the energy deposited in 

these varistors for three arbitrary source impedances (assumed 

to be ohmic), using the EMTP program [13] to input closedform equations for the open-circuit surge voltage. With the 

220-V level of the Long Wave, predictably the current in a 

130-V rated varistor is very low and the resulting energy 

deposition is negligible. The results for the Ring Wave and 

Combination Wave are shown in Table 3. These simple 

illustrations show that the concept of "specific energy" cannot 

be used to select a candidate varistor energy-handling rating. 

VI. HOW TO PROCEED IN mTTURE SURVEYS 

In an effort to acknowledge the legitimate quest for the 

single number characterization, we should offer alternatives, not 

just stay with a negative vote The solution might be to tailor 

the surge characterization to the intended application, that is, 

take into consideration the failure mode of the specific 

equipment, and present the data in a form most suited for that 

equipment. Of course, this would mean not only avoiding a 

single number, but actually providing combinations of 

parameters, each combination best suited to a particular type of 

victim equipment, according to their failure modes. 

Another consideration that must be observed in conducting 

and reporting the monitoring of surges is the proliferation of 

SPDs in end-user installations. It is unlikely today to find an 

installation where some SPD is not present, either as a 

deliberate addition to the system, or as part of the connected 

equipment. Aware of this situation, some researchers have 

attempted to disconnect all known SPDs fkom the system being 

monitored so that results would represent the "unprotected 

location" situation such as that initially described in IEEE 587- 

1980 [14], the forerunner of ANSYIEEE C62.41-1991 [12]. 

However: even this precaution of disconnecting all known 

SPDs does not guarantee that some undetected SPD might not 

have been left connected somewhere and thus invalidate the 

record. Thus, extreme caution must be applied to reporting and 

interpreting voltage monitoring campaigns conducted after 

1980. 

The recently-approved IEEE Recommended Practice Std 

1 159 on Monitoring Power Quality [ 151 offers guidance on 

conducting surveys, including not only surges, but other 

parameters. The Working Group that developed this standard 

has now established task forces to develop further 

recommendations on processing and interpreting the recorded 

data, including more uniform formats. 

Table 4 presents a matrix of surge parameters and types of 

equipment, showing for each type of victim which surge 

parameter is significant or insignificant. The authors have 

sought to identify all types of potential victims (and invite 

additions to this list). Inspection of Table 4 reveals that the 

[v2 X dt] integral, alone, is not directly involved in the failure of 

any of the listed equipment. 

TABLE 2 

ENERGY DEPOSITED M A VARISTOR BY A "1 JOULE SURGEn FOR THREE DIFFERENT VALUES OF SOURCE IMPEDANCE 

I surge parameters I SourceNaristor Response to Surge I 

Rectangular, 

1000 V - 50 p~ 

("Effective energy% 1 J) 

Source 

impedance 

(Q) 

2 

50 

400 

Varistor 

cwent 

(A) 

330 

14 

1.8 

Varistor 

voltage 

(V) 

340 

300 

280 

Varistor 

impedance 

(Q) 

1 

21 

156 

Power in 

varistor 

(W 

112 200 

4200 

504 

Energy in 

varistor 

(J) 

5.6 

0.2 1 

0.025 
TABLE 3 

ENERGY DEPOSITED M VARISTORS BY RING WAVE AND COMBINATION WAVE "1 JOULE SURGES 

St in 

device* 

Surge parameters 

(All for 1 J) 

Ring Wave 

100 kHz 

0.5 ps rise time 

Combination 

Wave 

1.2150 ps 

TABLE 4 

SIGNIFICANT SURGE PARAMETERS (X) IN THE EQUIPMENT FAILURE MODES 

* The I4 in the device is actually the result of the combination of surge parameters and device response to the surge. 

Like other power and energy-related equipment stress, k is not an independent parameter of the surge. 

**Amount of final carbonization, not the initial breakdown. 

Type of 

equipment 

Insulation - Bulk 

- Windings 

- Edges 

Clamping SPDs - Bulk 

- Boundary layer 

Crowbar SPDs 

Semiconductors - Thyristors 

- Triacs 

- IGBTs 

Power conversion - DC level 

- Other 

Data processing malfunction 

FOR DIFFERENT 

Source impedance 

I a 

12 51 

50 62 

pp~~ 

I a 

12 

50 a 

Surge parameters 

SOURCE AMPLITUDES AND 

Vanstor nominal 

voltage (V) 

130 

150 

275 

130 

150 

275 

130 

150 

- 

275 

130 

150 

275 

130 

150 

275 

130 

150 

275 

Source 

impedance 

X 

X 

X 

X 

VARISTOR NOMINAL 

Peak current 

in varistor (A) 

2732 

2677 

2245 

23 9 

234 

208 

58 

57 

51 

800 

73 9 

426 

72.1 

68.4 

45.0 

17.7 

17.1 

11.4 

Maximum 

rate of rise 

X 

X 

X 

X 

X 

X 

X 

X 

Peak 

amplitude 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

VOLTAGES - 

Energy deposited 

in varistor (J) 

7.97 

8.53 

10.7 

0.55 

0.60 

0.81 

0.12 

0.13 

- 

0.18 -- -- 

10.8 

10.7 

6.24 

0.87 

0.89 

0.64 

0.21 

0.21 

0.16 

Tail 

duration 

X ** 

X 

X 

X 

X 

X 

Repetitio 

n 

rate 

X 

X 

X 

X, 
W. CONCLUSIONS 

The attempt to characterize the surge environment by a 

single number - the "energy in the surge" or "specific energy" 

-- is a misleading approach that should most definitely not be 

used in Power Quality research. There are at least three reasons 

for this prohibition: 

1. The concept that energy can be defined in the abstract from 

a single measurement of voltage across the lines of an 

undefined power system is a faulty oversimplification. 

2. The potential victims of a surge event have responses that 

reflect their design and for many, their failure modes can be 

totally independent of any energy consideration. 

3. The prime interest of energy consideration is related to the 

energy-handling capability of metal-oxide varistors. The 

energy deposited in such a device by a given surge event 

depends on amplitude, waveform, source impedance, and 

varistor characteristics, and not on the "effective energy.". 

Future surveys should be conducted keeping in mind the 

relevant parameters for characterization such as peak amplitude, 

maximum rate of rise, tail duration -- but not "energy." 

Furthermore, a relevant and realistic assessment of surge 

stress threats must consider not only all the characteristics of a 

surge event, but also the source of the surge and the failure 

niechanisms of potential victim equipment. 

WL ACKNOWLEDGMENTS 

Support for the development of this thesis, motivated by the 

discussions and contributions of IEEE and IEC colleagues, was 

provided by Delmarva Power & Light and by Pacific Gas & 

Electric. Support for the modeling was provided by the Electric 

Power Research Institute. 

M. REFERENCES 

[l] Goldstein, M. and Speranza, P., 'The Quality of U.S. Commercial AC Power," IEEE - INTELEC Conference Proceedings, 

1992. 

[2] Hughes, B. and Chan, J.S., "Canadian National Power Quality 

Survey Results," Proceedings, PQA '95 Conference, EPRI, 1995. 

[3] Martzloff, F.D. and Hahn, G.J., "Surge Voltages in Residential 

and Industrial Power Circuits," IEEE Transactions PAS-89, No.6, 

July/August 1970. 

[4] Allen, G.W. and Segall, D., "Monitoring of Computer 

Installations for Power Line Disturbances," IEEE Winter Power 

Meeting Conference Paper WHP WR C74, 1974. 

[S] Dorr, D.S., "Point of Utilization Power Quality Study Results," 

IEEE Transactions lA-31, No.4, JulyIAugust 1995. 

[6] Goedbloed, J.J., "Transients in Low-Voltage Supply Networks," 

IEEE Transactions EMC-29, No.2, May 1987. 

[7] Hassler, R, and Lagadec, R., "Digital Measurement of Fast 

Transients on Power Supply Lines," Proceedings, Third 

Symposium on EMC, Rotterdam, 1979. 

[8] Meissen, W., "Overvoltages in Low-Voltage Networks" (In 

German), Elektrotechnishe Zeitschrift, Vol. 104,1983. 

[9] Standler, R.B., "Transients on the Mains in a Residential 

Environment," IEEE Transactions EC-31, No.2, May 1989. 

[lo] Goulef K, "Susceptibility of Power Semiconductor-based 

Equipment to Power Line Disturbances," Conference 

Proceedings, Power Quality 1989. 

[ll] Scheuerer, F., "Research on the Isolation Properties of Solid 

Insulation Upon Occurrence of HF Overvoltages, (In German) 

Doctoral Thesis, Dannstadt University, 1993. 

[12] ANSYIEEE C62.41-1991, IEEE Recommended Practice on 

Surge Voltages in Low-Voltage AC Power Circuits, (Reaffirmed 

1995). 

[13] EPRI Report EL-6421-L, Electromagnetic Transient Program 

(EMTP), Version 2.0, Volumes 1 and 2, July 1989. 

[I41 IEEE 587-1980, IEEE Guide on Surge Voltages in Low-Voltage 

AC Power Circuits, 1980. 

[I 51 IEEE 1159-1995, IEEE Recommended Practicefor Monitoring 

Electrical Power Quality, 1995. 

Thomas Key (M' 1970, SM' 1984) is Manager of Systems 

Compatibilit at the EPRI Power Electronics A plica-tions center (mA ). ne received nis maa =om me Qniversny or 

New Mexico and ME in power engineering from Rensselaer 

Polytechnic Institute. He has served on several IEEE Color 

Book committees, including initiation and completion of the 

Emerald Book on powering and grounding sensitive loads. 

Arshad Mansoor (M' 1995) is an Electrical Systems Engineer 

at the EPRI Power Electronics Applications Center (PEAC). 

He received his MS and Ph.D. in electrical engineering fiom the 

University of Texas, Austin in 1992 and 1994 respectively. His 

areas of interest include Power Quality, power systems 

transients analysis, harmonics, surge propagation and 

protection, and EMTF' model development. 

Franqois Martzloff (M' 1956, F'1983) Born and educated in 

France, with additional MS degrees from Georgia Tech and fiom 

Union College, worked at General Electric for 29 years and now 

ten years at the National Institute of Standards and Technology. 

He is contributing to several committees for development of 

standards on EMC, surge protection and Power Quality in the 

IEEE and the IEC.