IEEE 013 Overvoltage Protectors - A Novel Concept for ... TRANSACTIONS ON POWER DELIVERY, VOL. 25,...

IEEE 013 July, 2010

Overvoltage Protectors – A Novel Concept for Dealing with Overbuilt

Distribution Circuits

Daniel J. Ward

Fellow, IEEE

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Cooper Industries’ products or services. Internal or personal use of this material is permitted. However, permission to reprint/replublish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected].

By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

Cooper Power Systems 2300 Badger Drive Waukesha, WI 53188 www.cooperpower.com P: 877.CPS.INFO

Cooper Power Systems is a valuable trademark of Cooper Industries in the U.S. and other countries.

You are not permitted to use the Cooper Trademarks without the prior written consent of Cooper Industries.

©2010 Cooper Industries. All Rights Reserved.

mailto:[email protected]

IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 25, NO. 3, JULY 2010 1971

Overvoltage Protectors—A Novel Concept forDealing With Overbuilt Distribution Circuits

Daniel J. Ward, Fellow, IEEE

Abstract—This paper deals with a simple solution to aproblem that has plagued overbuilt distribution circuits fordecades—namely, protection for sustained overvoltage events.When two overhead circuits of different voltages exist on the samepoles, the possibility exists that contact between the two circuitswill occur. When this takes place, damage and failures occur toutility equipment on the lower voltage circuit and to customers’end use equipment served from the lower voltage circuit. Tradi-tional approaches have met with limited success largely due totheir high costs or operational difficulties. The author’s preferredsolution utilizes polymer housed station class arresters on thelower voltage circuit to limit the resulting overvoltage. They areintended to be employed in an expendable mode (i.e., they need tobe replaced following a sustained overvoltage event). A field trialwas arranged to demonstrate the effectiveness of the approach.This trial proved to be quite successful and cost effective, leadingto the deployment of many more station class arresters for thisfunction on the Dominion distribution system. A screening tech-nique was devised to aid in applying the solution to a range ofdistribution voltage combinations and breaker/recloser clearingtimes.

Index Terms—Arresters, overbuilt construction, overvoltageprotection, power distribution lines.

I. INTRODUCTION

O VERBUILT distribution circuits refers to a practicewhere two or more overhead circuits are constructed

on the same poles. If the circuits are of different operatingvoltages, overvoltage problems can occur when contact is madebetween the two circuits.

Should a short circuit occur between the two circuits, thelower circuit will experience an overvoltage, resulting in manycustomers with damaged home appliances, electronics equip-ment, HVAC, lighting, etc. Additionally, some arresters andtransformers on the lower circuit will be damaged from theovervoltage event.

The fundamental problem is that most equipment on the lowervoltage circuit and the end-use equipment served from the lowercircuit cannot withstand the duty from this type of overvoltageevent. On a system of any appreciable size, multiple sustainedovervoltage events can be expected over the course of a year

Manuscript received November 06, 2009; revised February 17, 2010, March03, 2010, and March 12, 2010. First published April 26, 2010; current versionpublished June 23, 2010. Paper no. TPWRD-00822-2009.

The author is with Dominion Virginia Power, Richmond, VA 23261 USA(e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TPWRD.2010.2046343

(Dominion averages 13 a year). The problem is not unique toDominion; it is an industry problem.

Traditional solutions are quite expensive and at least threedifferent ones have been tried or considered by different electricutilities. Each has its own drawbacks.

First, one of the circuits can be relocated or even under-grounded (i.e., placed underground). Very often additionalright-of-way is not available and easements to construct under-ground facilities may not be available while overhead facilitiesare still in place. Even if one could overcome these obstacles,undergrounding is a very expensive option.

Next, the lower circuit can be converted to be the same op-erating voltage as the upper circuit. The result—should contactbetween the two circuits occur—is a voltage no higher than whatis normally supplied. This option may range from just changingout the transformers associated with the lower circuit to addi-tional equipment replacement like line insulators. In addition,the phase spacing may have to be reworked in many cases.

Finally, spacer cable can be used in place of bare wire on thelower circuit. Insulated wire has greater weight and sag thanwhat was there before and, as a result, requires shorter spanlengths and more poles for support. A similar concept which canbe retrofitted over existing lines involves insulating the phasewires of the lower circuit using a medium-voltage line cover.Like the spacer cable option, should a conductor with a linecover fall on the ground, there will be very little fault current.So they both have the disadvantage in that their use can resultin a high impedance fault situation with safety concerns to thepublic.

None of the aforementioned methods is a panacea for dealingwith overvoltage events from overbuilt circuits. Most of the so-lutions have not been widely adopted by utilities partly dueto the high cost and partly due to the operational difficultieswith some of them. A simpler and less expensive solution isneeded—particularly areas where repeat sustained overvoltageshave occurred.

II. INITIAL CONCEPT DEVELOPMENT

The initial objectives of this work were twofold, namely:1) to find a more cost-effective solution to the sustained over-

voltage problem. The solutions need to consider impacts toboth customer as well as utility equipment;

2) to utilize an off-the-shelf solution rather than one cus-tomized for each area to be protected.

For Dominion, the overbuilt distribution construction mostsusceptible to sustained overvoltage events involves an oper-ating voltage of 34.5 kV for the top circuit and either 13.2 kV or

0885-8977/$26.00 © 2010 IEEE

Authorized licensed use limited to: IEEE Publications Staff. Downloaded on August 02,2010 at 20:10:33 UTC from IEEE Xplore. Restrictions apply.

1972 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 25, NO. 3, JULY 2010

Fig. 1. Basic shorted overbuilt circuit—single phase equivalent.

Fig. 2. Fast-acting switch solution.

12.5 kV for the lower circuit. The available fault current at our34.5 kV distribution substations is 10 kA or less in most cases.

A single phase equivalent of an overbuild circuit is shown inFig. 1. The length of common distance between the two circuitsrepresents the exposure for possible contact between the circuitsand is important in helping establish whether one solution ormultiple solutions will be needed for the exposure zone. ForDominion, the exposure distance ranges from as little 0.8 km(0.5 mi) or less to 3.2 km (2 mi) or more.

Any means of rapidly detecting the overvoltage and inter-rupting the higher voltage source might represent a solution.One approach would require voltage sensing on the lowervoltage circuit, communications back to the recloser or circuitbreaker on the top circuit and rapid fault clearing by that pro-tective device. Concerns about lengthy overall clearing times aswell as for temporary overvoltages, which would either resultin an unnecessary interruption for a temporary overvoltageor would result in an imposed delay which would render theoverall scheme ineffective, caused this approach to be droppedfrom further consideration.

A simple modification to Fig. 1 shows the addition of a fast-acting switch, connected from phase to ground on the lowervoltage circuit, as one means of dealing with the overvoltageissue (see Fig. 2). As shown, this normally open switch is usedto bypass the affected region of the lower voltage circuit whensustained overvoltages occur. The switch would have to be ableto respond to overvoltages and be fast enough to limit or preventequipment damage.

A series of tests [1] using different distribution arresters, in-cluding normal duty and heavy duty, gapped and non-gapped,with and without isolators simulated dropping one phase of a46 kV line onto a phase of a 12.5 kV line. The available fault

Fig. 3. Overvoltage portion of the ITI Curve (2000 version).

current for these tests was either 1 kA or 2 kA, so it representeda fairly weak source. It can be expected that the condition ofthe distribution arresters would fare much worse under a higherfault current environment like 6 kA or so since the heating effectis proportional to . The author doubted whether distributionarresters—with or without isolators—represented a viable solu-tion to the overvoltage problem because reclosing is commonlyemployed for distribution circuit breakers and reclosers and theadditional fault duty from reclosing would likely destroy a dis-tribution class arrester. Nonetheless, it was of interest from theirexperiments that the secondary voltages were kept within theovervoltage limits of the 1996 CBEMA curve.

The Information Technology Industry Council or ITI devel-oped a later version of what was previously called the CBEMA(Computer and Business Equipment Manufacturers Associ-ation) curve. The overvoltage portion of the ITI curve [2] isshown in Fig. 3 below. Survivability of electronic equipmentis more likely if the coordinates for the voltage and time fallsbelow the solid curve. Electronic devices generally tend toperform better than indicated by the curve, not so much inmagnitude but in the duration of the event that can be withstoodbefore the device is damaged.

When 19.92 kV comes in contact with 7.62 kV, the maximumvoltage on the 7.62 kV phase is 2.61 times normal without theeffect of arresters. A maximum value of approximately 23 kVwas shown for a non-gapped 10 kV distribution arrester in [1].This is 2.1 per unit based on the crest of 7.62 kV. For micropro-cessor-based equipment to be protected, Fig. 3 shows that thetime must be limited to just under 1 ms for a 2.1 pu voltage. Wewill revisit this point later in this paper.

Arrester manufacturers generally favored a solution thatwould not only survive the overvoltage event but also beavailable for future events. While this permanent protectionapproach was understandable, the customized nature of thisapproach seemed likely to be a good deal more expensive andmore difficult to apply than one where the arresters would beallowed to fail and then simply be replaced. The author favoredone that did not have to be customized for each location. As a


WARD: OVERVOLTAGE PROTECTORS—A NOVEL CONCEPT FOR DEALING WITH OVERBUILT DISTRIBUTION CIRCUITS 1973

Fig. 4. SLGF current versus distance for a 3.7 km (2.3 mi) section.

result, the permanent protection approach was not consideredfurther.

This thought process led to the idea of employing a polymer-housed station class arrester as a fast switch for this type ofprotection. The concept was to use them as sacrificial devicesdesigned to be replaced following a sustained overvoltage event.

Station class arresters, particularly those with polymer hous-ings, have high energy handling capability and are readily avail-able as standardized products. Installing these on the distribu-tion lines with their proximity to the public made polymer hous-ings a requirement. In addition, station class arresters do nothave isolators and, as mentioned earlier, isolators would haverendered this protection ineffective because of reclosing.

The existing distribution arrester ratings were based on IEEEC62.22 [3]. The decision was made to employ the same voltagerating for the station class arresters as was found on the existingdistribution arresters. The assumption is that the station classarrester with its lower clamping voltage would hog the energyfrom nearby distribution arresters and prevent them from failing.

Insulation coordination issues are covered in [10] and [11].Furthermore, [11] uses the term sacrificial arresters in referenceto a scheme in which several sets of transmission arresters areswitched in to deal with the overvoltages due to load rejectionon a large 735 kV transmission network. So, from a high levelperspective, sacrificial arresters may have been used before attransmission voltages, but they have not been employed on dis-tribution circuits.

III. FIELD TRIAL

To demonstrate the feasibility or proof of concept, it was de-cided to perform a field trial. On August 9, 2007, Dominioncrews installed station class arresters on crossarms below anEast Richmond 13.2 kV circuit. Since the 10 kV arresters werefairly short in height, wildlife guards were added.

The 34.5 kV overbuilt circuit has an available fault currentof 9,376 A at the substation for a single line to ground fault(SLGF). The circuit exits the substation via underground cablefor 0.55 km (0.34 mi) and then goes overhead for another 3.2km (2 mi). The 34.5 kV circuit conductor size is 336.4 kcmilAAC. Fig. 4 shows the fault current versus distance for the first3.7 km (2.3 mi) of the circuit.

One set of arresters was installed at the source end of the over-head section (0.55 km from substation in Fig. 4) and another set1.6 km (1 mi) away. The circuit was selected from other poten-tial overbuild situations because it had 3 sustained overvoltage

Fig. 5. Overvoltage protector (OVP) installation.

TABLE IDIGITAL RELAY DATA ON FAULT CURRENT MAGNITUDES

events in the previous 4 year period. Fig. 5 shows a picture ofthe installation at one of the arrester locations.

On April 14, 2008, a vehicle struck a utility pole near the 1.6km (1 mi) location causing one of the phase wires from the 34.5circuit to break and come in contact with a phase of the 13.2 kVcircuit. The station class arresters on the affected phase operatedas planned at both arrester locations.

Both circuits employed two shot reclosing and had digitalrelays installed on them so there was data provided (Table I)about the sequence of operations along with the fault currentmagnitudes.

The data from the digital relays indicates that the 13.2 kVcircuit breaker tripped first, followed a second later by the 34.5kV breaker. The 34.5 kV breaker reclosed 10 seconds later andtripped out again. A second later, the 13.2 kV breaker reclosedand tripped out again. Some 34 seconds later, the 34.5 kVbreaker reclosed and then locked out. A second later, the 13.2kV breaker reclosed and locked out. The clearing times of thecircuit breakers were estimated from the relay settings and themeasured fault current.

As mentioned earlier, two arresters failed from the sustainedovervoltage event. Fig. 6 shows one of the failed arresters. Ascan be seen from the figure, the polymer housing split open.There is evidence of arcing internally and externally. It is likelythat the sustained overvoltage shorted the blocks and the internalpressure buildup caused the polymer housing to rip open. Thewrapping material around the blocks also split open revealinga stack of MOV blocks which were intact and in the normalalignment. The construction was sufficiently rugged to keep the



Fig. 6. One of the 2 failed station class arresters.

Fig. 7. Another failed arrester had expelled a disc.

arrester in the shorted mode throughout the reclosing duty ofboth circuit breakers.

Fig. 7 shows the other failed arrester. It showed damage sim-ilar to the companion arrester; however, one of the MOV discshad been expelled.

Approximately 300 residential customers were affected bythe incident. Although there was an interruption, there was noreported damage at any of the customers’ residences. Usuallyaffected customers contact our claims group within a few days,but no claims were ever reported for this event. In addition, therewas no damage to any other Dominion equipment includingthe distribution arresters on the 13.2 kV circuit. The operationscrews reported that the restoration process went smoothly. Oncethe failed arresters were isolated and the phase wire repaired,service was restored more rapidly than on any of the previousovervoltage events. The trial was a huge success.

IV. ENERGY HANDLING CONSIDERATIONS

To better understand what range of voltages and fault currentsthis method could be applied to, the author investigated the en-ergy transfer aspect of the problem.

The main factors involved with energy transfer are the op-erating voltages of the two circuits, the system impedance for

Fig. 8. Equivalent circuit for maximum power transfer.

the higher voltage circuit, the circuit breaker and recloser op-erating times, the number of reclosures and the impedance of afailed arrester. Although an MOV surge arrester is a nonlineardevice, once it is subjected to duty beyond its TOV (temporaryovervoltage) capability, the model reverts to a fundamental fre-quency one in which the resistance of the failed arrester can betreated as a fixed resistance value.

With an R-L circuit, it can be shown that the maximum powertransfer occurs when the arrester resistance

(1)

where and are the positive and zero sequence impedancesand represents the magnitude of the resulting impedance

See Appendix A for more details on the derivation of (1).Given the available sequence impedances, permits one to

calculate the portion of the maximum power delivered bya given circuit. The time factor accounts for the total durationof fault current that the arrester sees. The resulting equivalentcircuit is shown in Fig. 8.

When contact occurs from one of the top phases to the un-derbuilt circuit, the station class arrester on the underbuilt phasequickly shorts out and, since the arrester is grounded, a singleline to ground fault is initiated on the upper circuit. References[6], [9], and [12] describe a failure mode in which an MOV ar-rester when subjected to excessive energy fails due to adiabaticheating in under 1 ms. This is consistent with the field tests andthe earlier discussion of why the station class arrester approachpermits the overvoltage limits of the ITI curve to be met sincethe failure results in the valve elements shorting out almost in-stantaneously to a fairly low value.

The shorted arrester is subjected to the fault duty for the du-rations associated with the initial fault plus the subsequent re-closures of the 34.5 kV circuit and the reclosing duty of the 13.2kV circuit.

For the circuit used in the field trial, the contact between thetwo circuits occurred at a location nearly 2.15 km (1.3 mi) fromthe substation. At this location, the critical value of resistance

to permit maximum power transfer is 3.32 ohms. At thisvalue of , the calculated fault current would be 3,923 A. Thecorresponding energy through the arrester would be calculatedfrom

(2)

Applying the data of Table I to (2), the maximum energy de-livered is 263,313 kJ. Since the term is fairly high compared



Fig. 9. Per unit fault current and � �� versus the �� ratio.

to what is expected for a failed arrester, a parametric study wasconducted in which the value was varied over a wide range tobetter understand how fault current and delivered energy wereaffected.

The effect of arrester resistance on fault current and isshown in Fig. 9 with the results given in per unit of the maximumvalues. A value of 1 corresponds to the following values:an arrester resistance value of 3.32 ohms, a fault currentvalue of 3,923 A and an energy value of 231,362 kJ.

Note the breakpoint on energy at a value of 1 as pre-dicted by (1). At higher values, the fault current and energyvalues are less; at lower values, the fault current increases, butthe energy values rapidly drop off.

Since the measured initial fault current from the 34.5 kV cir-cuit (6,066 A) agrees with the calculated value (6007 A), onecan conclude that the actual resistance value for a failed arresteris more like 0.03 ohms or less. For that resistance value, the en-ergy delivered to the failed arrester is 2920 kJ.

As long as the resistance of the failed arrester is sufficientlylow, there is a high chance of success with the overvoltage pro-tector (OVP) concept.

With the expected energy handling requirement calculated,one next needs to compare this to the manufacturers’ data onenergy handling. Manufacturers typically rate their arrester han-dling capability relative to its MCOV rating. With a 10 kV ar-rester rating (8.4 kV MCOV) for 13.2 kV circuits, the energyhandling requirement from the previous calculations is 348 kJper kV of MCOV.

References [4]–[6] show there is really no meaningful arresterenergy handling rating for sustained overvoltage events [4]–[6].What exists are single shot and two shot energy ratings, butones applicable to impulse events and not sustained overvoltageevents. It is not even clear whether different arrester manufac-turers rate the energy handling capability on the same basis oruse the same amount of conservatism in their ratings. Nonethe-less, the author used the published single shot impulse ratings asa means of selecting and ranking arresters from competitive of-ferings. A minimum single shot rating of approximately 9 kJ/kVof MCOV was used to select an arrester for this application.While this rating is almost 40 times lower than what was re-quired based on the calculations, this led to trying the conceptin the field with two sets of arresters and hope that the resistanceassumptions were conservative.

Fig. A1. Special case when load is purely resistive.

V. CONCLUSIONS

The OverVoltage Protector was a simple idea employinghigh-energy station class arresters in sufficient quantities (orwith sufficient spacing) to limit the energy absorbed by anunderbuilt distribution circuit during a sustained overvoltageevent. To the author’s knowledge, this concept has never beentried before.

The successful field demonstration was based on calculationsof maximum power transfer during the most common contactsituation involving overbuilt circuits.

The critical assumption for the overall application was howmuch resistance is represented by a failed station class arrester.Although the author considered his assumptions to be reason-able, tests at a high power laboratory would provide more con-fidence in the results under varying short circuit conditions.

A screening technique was developed to assess the potentialof using this approach for other combinations of voltages andsource impedances.

The OVP concept is much more cost-effective than any ofthe other more traditional approaches undertaken by utilitiesdealing with sustained overvoltage events from overbuilt con-struction.

Since the success of the initial pilot demonstration, Dominionhas installed OVPs in a 30 different locations covering 34.5kV//13.2 kV and 34.5 kV//12.5 kV overbuild circuit combina-tions and more are planned.

APPENDIX AMAXIMUM POWER TRANSFER

With a simple series R-L circuit, if the load impedance ispurely resistive as shown in Fig. A1, then [7] shows that max-imum power transfer will take place if the load resistance, ,is equal to the magnitude of the series impedance (i.e., where

). This is an important result employed in the ar-rester energy handling calculation.

The situation involving contact between two circuits was an-alyzed for a single line-to-ground fault occurring immediatelyfollowing the instant in which the arrester exceeded its tempo-rary overvoltage (TOV) capability. In other words, the initialcontact between the two phase wires causes the arrester to sud-denly change from a relatively high impedance element to a rela-tively low impedance path which absorbs a considerable amountof energy until the fault is cleared.

For a single line to ground fault, the symmetrical componentsolution (see Fig. A2) shows the series connection of positive,negative and zero sequence diagrams, all of which are in series



Fig. A2. Sequence diagram interconnection for a SLGF.

Fig. A3. Simplified version of Fig. A2.

with 3 times the fault resistance. In this case, the fault resistancerepresents the arrester resistance.

By rearranging this circuit to look more like that of Fig. A1and with , becomes equal to:

(3)

The resulting simplified equivalent form of Fig. A2 is shownin Fig. A3.

Thus, maximum power transfer will occur when

(4)

or when

(5)

From the available sequence impedances, the critical value ofresistance will permit one to calculate the maximum energy thatcan be delivered from a given circuit. The resistance value for afailed arrester will then determine the required energy withstandrating for the arrester.

TABLE IIIMPEDANCE AND FAULT CURRENT VALUES

The total sequence impedance for the circuit of Fig. 4is equal to

(6)

APPENDIX BIMPEDANCES AND FAULT CURRENT

The positive and zero sequence impedance values along withthe calculated fault current values for a single line to groundfault are given in Table II. The impedances are given in ohms at34.5 kV.

ACKNOWLEDGMENT

The author would like to thank J. Woomer of Dominion forgiving the author the freedom to try a new and promising con-cept, D. Sullivan of Dominion for his insight on operational is-sues affecting the installation, S. Barnard of Dominion for hishelp with the mounting and installation requirements, and J.Woodworth (who was with Cooper Power Systems at the timeand is now with ArresterWorks, Inc.) for his continued encour-agement before the field trials.

REFERENCES

[1] G. L. Goedde, E. S. Knabe, and L. A. Kojovic, “Overvoltage protec-tion of distribution and low-voltage equipment experiencing sustainedovervoltages,” in Proc. IEEE Power Eng. Soc. Winter Power Meeting,1999, vol. 2, pp. 1202–1207.

[2] Information Technology Industry Council. Washington, DC, 2005.[Online]. Available: http://www.itic.org/technical/iticurv.pdf

[3] Guide for the Application of Metal-Oxide Surge Arresters for Alter-nating-Current Systems, IEEE C62.22-1997, 1997.

[4] J. J. Woodworth, Nov. 4, 2008, Understanding the arrester energy han-dling issue. [Online]. Available: www.ArresterWorks.com

[5] K. G. Ringler, P. Kirkby, C. C. Erven, M. V. Lat, and T. A. Malkiewicz,“The energy absorption capability and time-to-failure of varistors usedin station-class metal-oxide surge arresters,” IEEE Trans. Power Del.,vol. 12, no. 1, pp. 203–212, Jan. 1997.

[6] G. St.-Jean and A. Petit, “Metal-oxide surge arrester operating limitsdefined by a temperature-margin concept,” IEEE Trans. Power Del.,vol. 5, no. 2, pp. 627–633, Apr. 1990.

[7] A. L. Shenkman and M. E. Zarudi, Circuit Analysis for Power Engi-neering Handbook. Berlin, Germany: Springer, 1998.

[8] A. G. Yost, T. J. Carpenter, G. F. Lincks, H. O. Stoelting, and R. W.Flugum, “Transmission-line discharge testing for station and interme-diate lightning arresters,” IEEE Trans. Power App. Syst., vol. PAS-84,no. 1, pp. 79–87, Jan. 1965.

[9] M. Bartkowiak, M. G. Comber, and G. D. Mahan, “Failure modes andenergy absorption capability of ZnO varistors,” IEEE Trans. PowerDel., vol. 14, no. 1, pp. 152–162, Jan. 1999.

[10] A. R. Hileman, Insulation Coordination for Power Systems. NewYork: Marcel Dekker, 1999.

[11] Computational Guide to Insulation Co-ordination and Modelling ofElectrical Networks, IEC 60071-4, 2004.

[12] J. A. Martinez-Velasco, Power System Transients: Parameter Determi-nation. Boca Raton, FL: CRC, 2010.



Daniel J. Ward (F’04) received the B.E. degree fromStevens Institute of Technology, Hoboken, NJ, andthe M.S.E.E. degree from Union College.

He is a Principal Engineer with Dominion VirginiaPower, Richmond, VA. Prior to joining DominionVirginia Power, he spent 21 years at General Electric(GE), Schenectady, NY, and completed GE’s PowerSystems Engineering Course. At GE, he undertooknumerous studies for GE’s distribution businessunits related to distribution transformer, capacitor,network protector, and meter applications. He also

developed and taught a distribution course as part of GE’s Power SystemsEngineering Course and participated in teaching other GE courses related toengineering economics and loss evaluation. At Dominion Virginia Power, he isthe Lead Engineer involved in distribution studies aimed at system reliabilityimprovements. He also manages Dominion’s R&D activities in the distribution

area and is involved with equipment applications and power-quality investiga-tions. He has taught distribution engineering courses at Virginia PolytechnicInstitute and State University, Blacksburg, and Virginia CommonwealthUniversity, Richmond.

Mr. Ward chairs the ANSI C84.1 Committee on Voltage Standards for Elec-tric Power Systems and Equipment, is past Chair of the IEEE Distribution Sub-committee and the Herman Halperin Award Committee, and past Vice Chairof the Power Quality Standards Coordinating Committee. He is a member ofthe Transmission and Distribution Committee, the Insulated Conductors Com-mittee, and is a registered Professional Engineer in the State of Virginia. He hasauthored and coauthored more than 30 technical papers, including four prizepapers. He revised the distribution chapter for the 2006 edition of the StandardHandbook for Electrical Engineers (McGraw-Hill) and received the Power En-gineering Society’s Award for Excellence in Power Distribution Engineering in2000.


IEEE 013 Overvoltage Protectors - A Novel Concept for ... TRANSACTIONS ON POWER DELIVERY, VOL. 25,...

Documents

Transcript of IEEE 013 Overvoltage Protectors - A Novel Concept for ... TRANSACTIONS ON POWER DELIVERY, VOL. 25,...