NBS

Publi-

''**ions Reference

NAT'L INST. OF STAND & TECH

AlllOb 031431

NBSIR 81-2283

Development of Power System

Measurements — Quarterly Report

January 1, 1981 to March 31, 1981

R. E. Hebner

Electrosystems Division

Center for Electronics and Electrical Engineering

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

April 1981

Prepared for:

-QC

100

,1156

81-2283

1981

Department of Energy

Office of Electric Energy Systems

12th Street & Pennsylvania Ave., N.W.

N/lail Stop 3344

Washington, DC 20461

(UTlOHAL WUXBA* or tflAKOAMM

UBXAJIT

JUl 2 0 1981

NBSIR 81-2283

or 1 # DEVELOPMENT OF POWER SYSTEM

MEASUREMENTS - QUARTERLY REPORT

JANUARY 1, 1981 TO MARCH 31, 1981

R. E. Hebner

Electrosystems Division

Center for Electronics and Electrical Engineering

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

April 1981

Prepared for: Department of Energy

Office of Electric Energy Systems

12th Street & Pennsylvania Ave., N.W.

Mail Stop 3344

Washington, DC 20461

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
•• a i -J

•• ‘.rj,

i

.

i

*

f

*
ill

F oreword

This report is intended to summarize the progress on four technical

investigations during the second quarter of FY 1981. Although reasonable

efforts have been made to ensure the reliability of the data presented, it

must be emphasized that this is an interim report so that further

experimentation and analysis may be performed before the conclusions from

any of these investigations are formally published. It is, therefore,

possible that some of the observations presented in this report will be

modified, expanded, or clarified by our subsequent research.
1

V

TABLE OF CONTENTS

Page

Foreword ill

Abstract 1

1. INTRODUCTION 1

2. DC FIELDS AND ION MEASUREMENTS Project No: A018-EES 1

3. INCIPIENT FAULT DETECTION/LOCATION Project No: A063-EES 4

4. TECHNICAL ASSISTANCE FOR FUTURE INSULATION SYSTEMS RESEARCH

Project No: A053-EES 8

5. OPTICAL MEASUREMENTS FOR INTERFACIAL CONDUCTION AND BREAKDOWN

Project No: AQ57-EES 11

6. REFERENCES 14
-1 -

DEVELOPMENT OF POWER SYSTEM MEASUREMENTS ~ QUARTERLY REPORT

JANUARY 1, 1981 TO MARCH 31, 1981

Robert Eo Hebner, Jr., Editor

This report documents the progress on four technical

investigations sponsored by the Department of Energy and

performed by the Electrosystems Division, the National Bureau

of Standards. The work described covers the period

January 1, 1981 to March 31, 1981. This report emphasizes

the errors associated with measurements of the vertical

current density in an electrical environment consisting of

a dc field with space charge, the measurement of rf attenuation

in distribution cables, the onset characteristics of positive

and negative corona in compressed SFg gas, and the measurement

of the space charge density in transformer oil subjected to

60 -Hz excitation.

Key words: cables; dc fields; high voltage; incipient fault;

insulation; SFg; space charge; transformer oil.

1 . INTRODUCTION

Under an interagency agreement between the U. S. Department of Energy

and the National Bureau of Standards, the Electrosystems Division, NBS,

has been providing technical support for DoE's research on electric energy

systems. This support has been concentrated in four areas -- the

measurement of electric fields, the measurement of the electromagnetic

properties of solid insulating materials and cables, the measurement of partial

discharge phenomena in gaseous dielectrics, and the measurement of

interfacial electrostatic field distributions and of space charge density.

The technical progress made during the quarter January 1 to March 31, 1981,

is summarized in this report.

2. DC FIELDS AND ION MEASUREMENTS

Project No: A018-EES

The objectives of this effort are to investigate devices and measurement

techniques which may be used to characterize the electrical environment

near high voltage dc (HVDC) transmission lines, to evaluate methods being

used for calibrating such devices, and to develop and establish calibration

facilities at NBS which will permit independent verification of the

accuracy of user calibrations.
-2 -

Recent emphasis has been on ion-related measurements, including vertical

current density and determinations of homopolar and net space-charge densities.

The study of the errors associated with measurements of the vertical

current density in an electrical environment consisting of a dc field

with space charge has extended over several reporting periods. During

this reporting quarter, this study has been completed and the results are summarized in the following discussion. The measurement approach which was evaluated uses devices which have been used for many years in atmospheric

electricity research under the name "Wilson plate." A Wilson plate Is a conductor, generally a sheet of metal, which is connected to ground

through an ammeter. The current density is determined by dividing the

measured current by the appropriate plate area. The work which was completed during the reporting quarter was intended to evaluate the

magnitude of the error introduced by the lack of coplanarity between the

Wilson plate surface and the ground plane. As shown by the results,

raising the Wilson plate above the ground plane increases the measured

current in both the ac and the dc cases.

The Wilson plates were constructed from a 0.157-cm thick, copper-clad

(on one side), fiber glass sheet. Two different-sized plates were studied;

one was a square 10 cm on a side and the other was a square 8.5 cm on a side. For each size of plate, four different active areas were considered.

For the 10-cm plate, centrally-located, square, active areas of 2.5,

5.0, 7.5, and 10 cm square were used. For the 8.5-cm plate, centrally-located,

square, active areas of 2.5, 5.0, 7.5, and 8.5 cm square were used. In

those cases in which the size of the active area was smaller than the

size of the plate, a central section of the copper was isolated from the

outer section by a narrow slot milled through the copper. The active

region is connected to ground through an ammeter while, in those cases

in which the active area is smaller than the plate, the square frame

around the active area, which is called a guard ring, is grounded directly.

The measurements were performed using an NBS-developed parallel -plate

facility [1] which permitted the generation of a known ac field or the

generation of a known dc field with space charge. The Wilson plate under

test was placed between the parallel plates of the test facility either on or a known distance above the test facility's grounded plate. Using 4 kV,

60-Hz excitation of the para! lei -plate structure with a plate separation

of about 0.5 m, displacement currents were measured with each of the

plates listed above. For the dc tests, the electric fields ranged from

7-33 kV/m and current densities varied from 0.025 to 4 yA/m. Figure 1 summarizes the data taken with ac and the data taken with dc excitation.

From this figure, it is seen that the width of the guard ring becomes

increasingly significant as the elevation above the ground plane is

increased. For example, this figure indicates that elevating a one-meter

square Wilson plate 2 cm above the ground plane would introduce an error

of the order 5 percent.
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As shown in figure 1 measurements of the dc field with space charge

indicate that, except for the case in which there is low space charge

density and a guard ring, the ac and dc results were not the same.

It is postulated that the error in figure 1 is due to field distortion

introduced by the Wilson plate and, in the dc case, because the space charge

increases the conductivity of the air. It should also be emphasized

that for the plates with no guard ring the dc data lies well below the

ac data. This effect is presumably a result of the plate design used in

this study. The fiber glass backing permitted the ions to reach only

the top side of the copper plate. In the ac case, however, the displacement

current coupled to both sides of the copper plate.

The conclusion of this study is that, in general, unguarded

Wilson plates should be used only if the sensor plane can be made to

coincide very closely with the ground surface. More flexibility is

available if the sensing plate is guarded.

In addition to measuring the vertical current density, it is also

important to measure the space charge density. During the reporting

quarter, measurements were made on a high efficiency particulate air

(HEPA) or “absolute “ filter. It was determined that for a wide range of

air flows and space charge densities, the filter removes more than 99

percent of the ions. The measurements suggest that the filtration devices

can be developed for use in calibrating ion counters.

In the coming quarter, the summary of the work done with the absolute

filter will be prepared for publication. NBS staff will also participate

in a measurement field day to be held at Project UHV in Massachusetts.

Finally, the study of ion-counters will continue with emphasis on modeling

and on the comparison of calculations and measurements for parallel -plate

ion counters.

For further information, contact Dr. R. H. Mcknight, (301) 921-3121.

3. INCIPIENT FAULT DETECTION/LOCATION

Project No: AQ63-EES

The objective of this program is to identify and, insofar as practical,

remove technical barriers to the development of a successful incipient

fault detector/locator for underground power transmission use. NBS

responsibility includes conducting an experimental program that will aid

the development of an incipient fault detection/location system by

measuring the rf characteristics of power cables and evaluating the

frequency content of partial discharge pulses emanating from incipient

fault sites in a cable dielectric.

Previous measurements at NBS had indicated that the attenuation of the

high-frequency components in the applied voltage pulse limits the resol uti on

„
-5-

One possibility is that the attenuation occurs because of the impedance

mismatch between the TDR unit (output impedance of 50 ohms) and the power

cable. Mismatched impedances between the TDR unit and the cable create

a double loss inasmuch as both the incipient wave and the reflected wave

(forward and reverse traveling waves) must pass through the mismatch

interface. Also, multiple reflections can occur within the cable under

these conditions which further complicate the analysis and understanding,

A second possibility is that the high-frequency attenuation is caused by

the inherent characteristics of the power cable.

Measurements had been made with a variety of impedance transitions

(e.g., abrupt, resistively-adapted, tapered) between the test system and

the cable in an attempt to separate the attenuation of the high-frequency

components due to the transition coupler from the attenuation in the

cable. By using the same transition couplers and cable terminations

while measuring two different lengths of the same cable, we were able to

study attenuation in the cable itself. The results were in good agreement

with previous data obtained on single-length sections implying that the

reflection problem had been properly treated. Since the results using

the different techniques are consistent, we feel the systematic errors are negligible. Figure 2 shows the attenuation of a distribution cable sample

(insulated with cross-linked polyethylene) as a function of frequency.

These measurements indicated that of order 5 dB/m at 1 GHz. The implication

of this attenuation in practical cables is demonstrated, by an example,

in figure 3. This figure shows a comparison of the measured reflection

from a short at the end of a 4 cm sample with the same coefficient for a 163 cm sample. The transition time of the reflection signal is about a factor of 2 less for the shorter cable than for the longer one because

the longer cable attenuates the high frequency components of the signal.

Preliminary results suggest that the loss occurs primarily in the

semiconducting screening layers adjacent to the inner and outer conductors.

For the one cable studied, the removal of the outer screen layer reduced

the attenuation from 4.1 dB/m to 1.8 dB/m at 1 GHz and further removal of

the inner screen reduced the attenuation to 0.7 dB/m.

In summary, the high intrinsic attenuation of rf signals in extruded

polyethylene distribution and transmission cables makes conventional time

or frequency domain reflectometry techniques using frequencies below a gigahertz impractical for the detection of incipient faults. In a cable

with modified screening layers detection at a distance of a few meters

may be feasible. Since most of the losses do occur in the screening

layers, another possibility exists. If higher frequency (several GHz)

waveguide modes could be excited in the polyethylene in a frequency

range of minimal attenuation, these modes should be extremely sensitive

to the presence of small defects in the dielectric. Present efforts at

NBS are aimed in that direction.

For further information contact Dr. W. E. Anderson, (301) 921-3121.
Attenuation

Of

14kV

Cable

- 6-

(jaj0|/\j/8P) uojjenueuv

Figure

2.

Attenuation

in

a

distribution

cable

asa

function

of

frequency.
Shorted

Power

Cable,

Length

4

cm

7

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Figure

3.

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upper

drawing

shows

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short

encountered

after

a

signal

propagates

through

4

cm

of

cable

while

the

lower

one

shows

the

coefficient

after

163

cm.

The

increase

in

transition

time

for

the

longer

cable

is

attributed

to

high

frequency

attenuation.
-8 -

4. TECHNICAL ASSISTANCE FOR FUTURE INSULATION SYSTEMS RESEARCH

Project No: AQ53-EES

The objective of this project is to develop diagnostic techniques to

monitor, identify, and predict degradation in future compressed gas

electrical insulating systems under normal operating conditions. Focus

is on the fundamental information and data needed to improve test design

and performance evaluation criteria. The investigation of partial

discharges (corona) in gaseous dielectrics is emphasized. This phenomenon

gives rise to degradation of the gas under high electrical stress and may

lead to breakdown. Measurement of partial discharge inception in highly

nonuniform fields may also prove to be a preferred method to determine

dielectric strength of electronegative gases.

Planned activities for FY -81 include: (1) estimate the sensitivity of

low-frequency dielectric constant measurements as a monitor of polar

molecules in SFg; (2) determine effects of trace amounts of H 2O and other

polar gas molecules on partial discharge behavior in SFg; (3) prepare an archival publication on pulse characteristics of positive and negative dc corona in SFg; (4) examine the effect of radiation on electron avalanche

development and measure the radiation emitted by corona; (5) identify

gaseous decomposition products resulting from corona in mixtures of SFg

with N 2 , CO 2 , c-C4Fg and CHF3 , and, for corona in SFg, determine the rate

of buildup of oxyfluorides as a function of discharge power; ( 6 ) model

discharge inception and test these models in a control led-ionization-zone

test cell (in collaboration with MIT); and (7) initiate a program to

evaluate electrical breakdown data for gases (in collaboration with

NBS-J1LA). In addition, there was an incomplete investigation in FY-80,

namely, the measurement of laser-induced optogalvanic signals in electric

discharges of rare gas -SFg mixtures to determine the effectiveness of

SFg in quenching metastable species.

Progress was made during the reporting quarter on all activities except

(1) which is completed and (2) which is nearly complete. The major

effort, however, has been the completion of activity (3). An example of a recent accomplishment in this area at NBS is a study of the effects of point

electrode diameter, uv radiation, and voltage polarity on the onset and

pulse characteristics of dc corona for pressures from 50-500 kPa.

Previous measurements performed in our laboratory [2-4] and elsewhere

[5] have shown that over the pressure range considered here, the onset of

negative corona occurs at a lower voltage than does positive corona

and the difference between the two increases with increasing gas pressure.

This polarity effect is attributed to the longer time lag associated

with initiating-electron production for positive corona compared to

negative corona, i.e., once the electric field is high enough to permit

development of electron avalanches of sufficient size, the probability

for initiating electron formation is lower for a positive point electrode.
-9-

It is hypothesized that, in the absence of radiation, the electronavalanche-initiating electrons for negative corona at onset are predominately

produced by field emission from the point electrode surface, and for

positive corona by colli si onal detachment of negative ions [6]. For the

negative case, the extent to which field emission is possible is, of

course, determined by the point electrode surface conditions [4]. If

the work function of the surface is too high, or if the field at the

surface is too low, as for points of relatively large radii of curvature,

then the conditions for electron emission may not be satisfied and considerable

overvoltage may be necessary to achieve inception. For such cases, the

positive corona inception voltage may actually be lower than the negative

inception voltage. If uv radiation is present, the probability for

initiating electron production may be enhanced in the negative case by

the photoelectric effect and in the positive case by photodetachment of

negative ions.

Ignoring the probability for initial electron formation, theory based

on the streamer criterion predicts that the positive and negative corona inceptions for SFg should be nearly the same [5,7]. Thus,

if the probabilities for initiating electron production can be made

comparable for each polarity, then the differences in inception should

be reduced. This condition can be achieved either by irradiating the gap

with uv-light or by increasing the size of the point electrode, i.e.,

diminishing the degree of field nonuniformity in the gap. In either

case, the effect should be greatest for positive corona because the electron

initiation probability for this case is lower due to the fact that the

avalanche-forming electrons originate from a small active volume in the

gas. This active volume is infinitesimally small at the theoretical

inception and becomes larger with increasing voltage.

These predicted trends were verified by measurement of corona inceptions

in SFg performed during the past reporting period. The results are indicated in figures 4a -d which show data on corona pulse rate and average

discharge current versus applied dc voltage for two point-electrode

diameters and two gas pressures. For figures 4a and 4c the point diameter

was 0.94 mm and for figures 4b and 4d it was 0.1 mm. For the smaller

point, data for both irradiated and nonirradiated gaps are shown. For

the larger point, it was necessary to irradiate to observe corona. For

negative corona in this case, the measured average discharge current is

also shown. Details of the measurement system used to obtain these data

have previously been given [2,4]. A comparison of the data in figures

4a and 4c with those respectively in figures 4b and 4d clearly indicate

that the polarity difference was lower for the larger electrode. In

figures 4b and 4d it is seen that the presence of uv radiation also

reduces the effect. These observations are consistent with the proposed

mechanisms for discharge initiation.

For the larger point diameter (0.94 mm), measurements were performed

to determine the pulse-height distribution of the corona pulses. The

trends in these data are consistent with those reported for corona from

the 0.1 mm point [2,4,8]. In particular, the positive corona begins as relatively small electron avalanches with a mean amplitude less than 1.0 pC

which changes abruptly at higher voltages (see the arrow in fig. 4c)

into large streamer pulses, or pulse bursts with a mean amplitude greater

than 10 pC.
AVERAGE

CURRENT

|AMPS|

10

(a) (b)

(c) (d)

Figure 4. Corona inception measurements in SFg. The data for point-plane geometry; for (a) and (c) point

tor C b ; and (d) 0.1 mm. The repetition rate is

pulses measured per second.

were taken

diameter 0.94 mm,

the number of
-11 -

During the next quarter, major emphasis will be placed on completing

an archival paper on the comparison of ac and dc corona inceptions in SFg.

This is considered a follow up to the work presented at the 1980 CEIDP

[3], and will indicate completion of activity [6]. An effort will be

made to begin the measurements associated with activity [5]. More work

will be performed on optogalvanic spectroscopy and on effects of uv radiation on corona in SFg, activity [2], The emphasis of the latter

measurements will be on determination of wavelength dependence of the

effect. Electric field calculations will be performed to aid the theoretical

prediction of corona inceptions. Investigations will be carried out to

improve the quantitative analysis of trace H 2O content in compressed SFg.

For further information contact Dr. R. J. Van Brunt, (301 ) 921-3121 .

5. OPTICAL MEASUREMENTS FOR INTERFACIAL CONDUCTION AMD BREAKDOWN

Project No: A057-EES

The objective of this project is to develop techniques to measure the

interfacial phenomena which influence the electrical breakdown characteristics

of composite insulation systems. This study concentrates on oil-paper

(pressboard) systems. The measurement of the electric field and/or the

space charge is made electro-optically using the Kerr effect in transformer

oil. This study is limited to those cases in which the solid insulator

is either parallel or perpendicular to the electric field.

Previous NBS investigations have shown that for a clean, wellcharacterized system, breakdown does not necessarily occur at an oil-paper

interface [9]. The study has been extended to include oils which are not of laboratory purity. Oil samples were obtained of two levels of

contamination (one a rinse oil and the other oil removed from a transformer

which had failed) from the Westinghouse Electric Corporation, Large Power

Transformer Division, Muncie, Indiana.

Before the breakdown studies were performed, measurements of the space

charge density were attempted by measuring the electric field as a function

of position between parallel plates. Using the clean oil and the rinse

oil, the distortion of the electric field due to space charge was less

than ± 3% of the average field. These measurements were made under

nearly uniform field conditions, 60-Hz ac excitation, and at room temperature.

More extensive measurements, however, were carried out in the

most heavily contaminated oil. These measurements suggest that space

charge effects may become significant at higher temperatures.

This contaminated oil, which had been removed from a transformer that

failed, had the levels of particulate contamination shown in table 1 [10].
- 12 -

Table 1. Summary of particulate contamination

Particle Size

ym Contaminated Oil

Number of Particles/ml

Normal Oi

1

3 - 150

50-150

1221

60

40 - 70

0.1 - 0.2

About 98-99% of the particulates were cellulose (from the paper or pressboard in

the apparatus) with the remaining being iron or copper.

Figure 5 summarizes the electric field measurements in the contaminated

oil. At room temperature, this oil exhibited no measureable field distortion,

that is the electric field was uniform to within 2% of its average value.

Near 55°C, the field was uniform to within about ± 2%; there may, however,

have been some enhancement at the anode and a decrease of the electric

field strength at the cathode.

For the temperature near 68°C a distortion was observed in the electric

field profile. The change in the field from one plate to the other was about 5% of the average electric field between the plates. If this is

space-charge field distortion, and not an artifact of the apparatus,

then the space charge density which could produce such a distortion

would be about -1.5 nC/cnr3. It must be stressed that this is a preliminary

measurement and must be further substantiated before confidence in such

a result is established. In comparison, the amounts of space charge

which are found in nitrobenzene are easily a factor of 200 times larger

than the value listed above for oil.

Measurements of the Kerr coefficient of transformer oil as a function

of temperature were started this quarter and will continue the next

quarter. These measurements are needed to quantify the space charge as higher temperature transformer oil is analyzed.

Drawing from the indication of space charge obtained this quarter,

efforts will be made next quarter to measure field distortions in

transformer oil at higher temperatures with 60-Hz stress and dc. Both

clean and contaminated oil will be employed. Known contaminants will also be

injected into the clean oil system to explore their effects. Attempts

will also be made to employ spacers parallel and perpendicular to the

fiel d

For further information, contact Dr. E. F. Kelley, (301) 921-3121.
-13-

Figure 5

(ANODE) (CATHODE)

POSITION, z

The electric field as a function of position between oarallel niatoc

suggests^hat'the' ^-tures Th" Zl 'rtePc

<~5*> confr?L«on

SP

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a

oCe

the

h

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S

i^ir "* mak1 " 9 3

in
-14-

6. REFERENCES

[1] M. Misakian, "Generation and Measurement of DC Electric Fields With

Space Charge," Nat. Bur. Stand. (U.S.), NBSIR 80-2177 (1980).

[2] R. J. Van Brunt, M. Misakian, D. A. Leep, K. J. Moy, and

E. C. Beaty," 1980 Annual Report: Technical Assistance for Future

Insulation Systems Research," Nat. Bur. Stand. Interagency Report,

NBSIR 81-2242 (1981).

[3] R. J. Van Brunt and M. Misakian, "Comparison of DC and 60-Hz AC

Positive and Negative Partial Discharge Inceptions in SFg," Proc.

Conf. on Electrical Insulation and Dielectric Phenomena, National

Academy Press, Washington, D.C., pp. 461-469 (1980).

[4] R. J. Van Brunt and D. A. Leep, "Characterization of Point-Plane

Corona Pulses in SFg," submitted to J. Appl . Phys. (1981).

[5] 0. Ibrahim, "Corona Stabilization and Breakdown in SFg and

SF 6 /N 2 Mixtures," Ph. D. thesis, Univesity of Strathclyde, Glasgow,

Scotland (1980). 0. Parish, 0. E. Ibrahim, and C. Korasli, "Corona

Stabilization and Breakdown in SFg and SFg/N 2 Mixtures," 5th Int.

Conf. on Gas Discharges, IEE Pub! . No. 165, pp. 320-323 (1978).

[6] B. C. O'Niell and J. D. Craggs, "Collisional Detachment of Electrons

in Sulphur Hexafluoride," J. Phys. B, Vol. 6, pp. 2634-2640 (1973).

[7] T. Nitta and Y. Shibuya, "Electrical Breakdown of Long Gaps in

Sulfur Hexafluoride," IEEE Trans. Pow. App. Syst., PAS-94,

pp. 1749-1754 (1975). The polarity effect should be small according

to the streamer criterion since the integration over the effective

ionization coefficient for the gas should be independent of direction

provided the field also changes sign. A small polarization effect,

however, is possible as noted in this reference.

[8] R. J. Van Brunt, J. S. Hi! ten, and D. P. Silver, "Partial -Discharge

Pulse Height Distributions and Frequencies for Positive and

Negative DC Corona in SFg and SF 6

-N 2 Mixtures," Gaseous Dielectrics II , Proceedings of the Second International Symposium on Gaseous

Dielectrics, Pergamon Press, pp. 303-311 (1980).

[9] E. F. Kelley and R. E. Hebner, Jr., "Breakdown Between Bare Electrodes

With an Oil-Paper Interface," Nat. Bur. Stand. (U.S.) NBSIR 80-2071

(1980).

[10]

K. E. Miners, private communication.
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 81-2283

2. Performing Organ. Report No, 3. Publication Date

4. TITLE AND SUBTITLE

Development of Power System Measurements -- Quarterly Report

January 1, 1981 to March 31, 1981

5. AUTHOR(S)

R. E. Hebner

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No. EA-77-%-01-60?0

eement:

8. Type of Report & Period Covered

Quarterly

1/1/81 to 3/31/81

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State. ZIP)

Department of Energy

Office of Electric Energy Systems

12th Street & Pennsylvania Ave., N.W., Mail Stop 3344

Washington, D.C. 20461

10.

SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report documents the progress on four technical investigations

sponsored by the Department of Energy and performed by the Electrosystems

Division, the National Bureau of Standards. The work described covers

the period January 1, 1981 to March 31, 1981. This report emphasizes

the errors associated with measurements of the vertical current density

in an electrical environment consisting of a dc field with space charge,

the measurement of rf attenuation in distribution cables, the onset

characteristics of positive and negative corona in compressed SFg gas,

and the measurement of the space charge density in transformer oil

subjected to 60-Hz excitation.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) cables; dc fields; high voltage; incipient fault; insulation;

SFg; space charge; transformer oil.

13. AVAILABILITY

|X I Unlimited

| | For Official Distribution. Do Not Release to NTIS

PH Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

19

15. Price

$5.00

USCOMM-DC 6043-P80
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