very fast transients in gis

2450 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 20, NO. 4, OCTOBER 2005

Frequency Characteristics of Very FastTransient Currents in a 245-kV GIS

M. Mohana Rao, M. Joy Thomas, and B. P. Singh

Abstract—The conducted as well as the induced voltages on con-trol cables and control circuits due to transient electromagnetic(EM) fields generated during switching operations in a gas-insu-lated substation (GIS) depend on the waveshape of the very fasttransient overvoltages and the associated very-fast transient cur-rents (VFTCs). The aim of this paper is to build a basis for charac-terizing the VFTC generated in gas-insulated switchgear and theassociated equipment during switching operations for the study oftransient coupling phenomena. The peak magnitudes of VFTC andtheir dominant frequency content at various locations have beencomputed in a 245-kV GIS for different switching operations aswell as substation configurations. Finally, the influence of the sub-station layout on the frequency spectrum, dominant frequencies,and the highest possible frequency component of the VFTC at var-ious distances from the switch have been reported.

Index Terms—Electromagnetic compatibility (EMC), electro-magnetic interference (EMI), frequency spectrum, gas-insulatedswitchgear (GIS), switching, very-fast transient currents (VFTCs),very-fast transient overvoltages (VFTOs).

I. INTRODUCTION

VERY-FAST transient overvoltages (VFTOs) generateddue to switching operations in a gas-insulated switchgear

(GIS) and the associated very-fast transient currents (VFTCs)could have a rise time ranging from 4 to 7 ns [1]. The peak mag-nitude of the transient current may be about a few kiloamperesdepending on the location of the switch operated, the substationlayout, and the observation point. These transient voltagesand currents radiate electromagnetic (EM) fields during itspropagation through the coaxial GIS bus section as the associ-ated frequencies are in the range of a few megahertz to abouta few hundreds of megahertz. The transient electromagneticfields, in turn, leak out into the external environment throughdiscontinuities such as gas-to-air bushing, gas-to-cabletermination, nonmetallic viewing ports, insulated flanges, etc.and get coupled to the control equipment or data cables presentin the GIS [2]. This coupling produces transient current/voltageon the shield of the control cables. Depending on the transferimpedance between the shield and the central conductor ofthe cable, the transient voltage appears at the terminals of thecontrol cable. Pigtail coupling can also take place between theshield pigtail and the central conductor of the control cables. In

Manuscript received March 8, 2004; revised September 30, 2004. Paper no.TPWRD-00117-2004.

M. M. Rao and B. P. Singh are with Bharat Heavy Electricals Ltd., Cor-porate R&D, Hyderabad 500 093, India (e-mail: [email protected];[email protected]).

M. J. Thomas is with the Department of High Voltage Engineering, Indian In-stitute of Science, Bangalore 560 012, India (e-mail: [email protected]).

Digital Object Identifier 10.1109/TPWRD.2005.852362

addition to the radiated EM field coupling, conducted mecha-nisms are also responsible for the coupling of very-fast transientcurrents to the control wiring. The current transformer (CT)and the potential transformer (PT) get conductively coupled tothe high-voltage bus of the GIS through the stray capacitancebetween the primary and secondary as well as the Faradayshields. Because of this coupling, a portion of the bus transientcurrent couples directly to the central conductor of the controlcables which, in turn, may appear at the terminals of the relayor data-acquisition (DAQ) systems, etc. connected to them[3]. All of these modes of coupling summed up with differentwaveshapes, frequency content, and relative phase shift result ina waveshape different from that due to any one of the couplingmechanisms acting alone [4], [5].

The protection of the control circuits against the induced tran-sients is an important aspect for the reliable operation of a GIS.Malfunctioning of the primary/secondary equipment has beenreported by many authors during switching operations in a GIS[1], [2], [6]. Since the transient voltages in control circuits de-pend on the nature of the radiated EM fields, it becomes nec-essary to estimate the magnitude and waveshape of the VFTCalong with its frequency spectrum. Further, knowledge of theVFTC characteristics would be required in the theoretical studyof EM field coupling as well as shielding of the sensitive sec-ondary equipment used in modern GIS.

This paper covers the estimation of VFTC at various loca-tions in a GIS for different switching operations. The config-urations, such as small length of the bus section, high capac-itance terminal components, and multiple branches of the bussection on the source/load side of the switch, are consideredfor the study. The peak magnitude of the transient currents atdifferent locations and their attenuation with time/distance arecalculated for various switching configurations. The variationin the frequency spectrum of the VFTC with distance from theswitch operated for different switching configurations and sub-station layouts have been analyzed. The approach used in thepresent study can be extended to any other GIS also regardlessof the size, rating, type, etc. EMC problems due to VFTC areof most concern for system voltages above 245 kV and at thesevoltages, segregated-phase GIS is normally used. Hence, such asystem has been taken up for the study.

II. VERY-FAST TRANSIENT CURRENTS (VFTCs)

The parameters that characterize the VFTC are of more rele-vance for the protection of GIS controls and are as follows [7]:

1) amplitude of VFTC;2) attenuation of the amplitude of VFTC with distance and

time;

0885-8977/$20.00 © 2005 IEEE

RAO et al.: FREQUENCY CHARACTERISTICS OF VERY FAST TRANSIENT CURRENTS IN A 245-kV GIS 2451

Fig. 1. Single-line diagram of a 245-kV GIS.

3) dominant frequency components of the VFTC;4) variation in the frequency content of VFTC with distance.Fig. 1 shows the single-line diagram of a segregated-phase

245-kV GIS used for the VFTC studies. The incoming line ofthe GIS is comprised of an overhead transmission line of 5-kmlength, an XLPE cable of 8-km length, PT, lightning arrester(LA), earth switch (ES), disconnector switch (DS), etc. TheXLPE cable and the power transformer (T1) locations are as-sumed as source and load side of the switch being operated,respectively. The most onerous condition during a switchingoperation is given for a voltage collapse of 2 p.u. (i.e., 1 p.u.on the source side and p.u. on the load side) and this hasbeen simulated in the present study. The equivalent circuits forGIS components and the spark channel that develops betweenthe switching contacts are essential for calculating the transientcurrent levels. Table I gives the electrical equivalent represen-tation of various GIS components. The gas breakdown betweenthe switching contacts during its operation is simulated as a se-ries connection of time-varying resistance and a fixed induc-tance of 5 nH. The role of inductance becomes significant espe-cially for fast rising pulses such as VFTC. In the present study,time-varying resistance during the build up of the spark channelis simulated using Toepler’s spark law [10]. According to this

(1)

where is Toepler’s constant in V-sec/m, l is length of the sparkchannel in meters, is initial charge, and is the spark col-lapse time in seconds. For the switching operations in a GIS, kvalue is taken as 0.005 V-sec/m. The integral in the spark law

TABLE IELECTRICAL EQUIVALENT REPRESENTATION OF GIS COMPONENTS [3], [8], [9]

sums up the absolute value of current through the resistanceover the time, beginning at the breakdown inception. The equa-tion for spark resistance is solved at each time step through it-erations by using the current integral along with the circuit pa-rameters (surge impedance of the bus, surge impedance of theswitch, capacitance between contacts, etc.). For this purpose, acomputer code has been developed. A fixed resistance of 2.5has been assumed for the spark channel after the spark collapsetime. The time step for the analysis is taken as 0.1 ns. The fol-lowing switching events are considered in the study:

1) SW1: Closing operation of the disconnector switch DS1,when DS3 and CB3 are open;

2) SW2: Closing operation of the disconnector switch DS3,when circuit breaker CB3 is open;

3) SW3: Closing operation of the circuit breaker CB3, whendisconnector switch DS6 is open.

Fig. 2 shows the equivalent electrical network of the 245-kVGIS during SW3 operation. The amplitude and waveformsof the transient currents have been estimated using Electro-magnetic Transient Program (EMTP). From the time-domaincurrent waveforms, the frequency spectra have been calculatedusing the fast Fourier transform (FFT) technique.

III. RESULTS AND DISCUSSIONS

Fig. 3 shows the waveforms of the transient currents at dif-ferent locations in a 245-kV GIS for the first switching opera-tion (SW1). From this figure, it is seen that the peak magnitudeof the transient current at DS1 is about 8.18 kA and the highestmagnitude of the transient current occurs at 3 m from the dis-connector switch DS1 [i.e., at the CT (listed in Table II)]. Thisis in contrast to the peak magnitude for VFTO, which occurs atthe open ends. The peak magnitude of the transient current atthe GIS-cable junction is about 7.29 kA. To understand the ef-fect of switching configurations on the peak magnitude of theVFTC at different locations, transient currents have been calcu-lated for the second switching configuration (SW2). From theresults, it is clear that the highest magnitude of transient current


Fig. 2. Equivalent electrical network of the 245-kV GIS.

occurs very near to the switch (i.e., at the BUS LINK). The peakmagnitude of the transient current at the GIS-cable junction isabout 4.12 kA. The reduction in amplitude of transient currentat the cable end for the SW2 operation may be due to the pres-ence of the gas-insulated bus-sections (245 kV BUS II) on thesource side and a smaller length of the bus section on the loadside of the switch. More clearly, the transient current dividesbetween the BUS II and the incoming line. To understand theeffect of high surge capacitance components on the peak mag-nitude of the transient currents, the third switching operation hasbeen considered and the results are shown in Fig. 4. From thisfigure, it is clear that the peak magnitude of the transient cur-rent at the switch operated is high compared to the other twoswitching operations and the highest magnitude of the transientcurrent occurs at 1.9 m from the switch (load side of CB3). Theincrease in transient current may be due to the high surge ca-pacitance on the load side of the switch. The peak magnitudeof the transient current at the GIS-cable junction is about 6.92kA. Also in the present configuration, the transient current di-vides between BUS II and the incoming line as in the case ofthe second switching configuration. From the above analysis,it is also clear that the peak magnitude of the transient currentnear the open end of the bus sections is significant (up to 3 kA)and is of higher value for the SW1 operation than for the othertwo switching operations. This may be due to a) the high ca-pacitance termination for the third switching configuration and,thus, the current flowing through the open end bus section islow; b) branching of the transient current between BUS II andthe incoming line for the SW2 and SW3 configurations.

The following salient features have been observed during theVFTC characterization.

Fig. 3. VFTC waveforms at three different locations for the first switchingoperation (SW1).

TABLE IITRANSIENT CURRENTS IN kILOAMPERES AT DIFFERENT GIS COMPONENTS.

1) VFTC waveform attenuates with time and approaches tozero within a few microseconds.


Fig. 4. VFTC waveforms at three different locations for the third switchingoperation (SW3).

2) The highest magnitude of the transient current occurs ator near the switch for all of the switching operations.

3) The peak magnitude of the transient current decreaseswith distance from the switch in either direction.

4) The peak magnitude of the transient current is low whenswitching on/off bus sections of smaller lengths.

5) The peak magnitude of the transient current and its wave-shape at different components of the GIS change witheach switching operation.

The peak magnitude of VFTC at various locations dependson the terminal component connected to the GIS. The terminalcomponent could be an XLPE cable or an overhead transmissionline or a gas-insulated transmission line (GITL). To understand

TABLE IIIDIFFERENT SUBSTATION LAYOUTS UNDER THE STUDY

Fig. 5. Variation in peak magnitudes of the VFTC with distance for varioussubstation layouts.

the effect of different terminations on the peak magnitude ofthe transient currents, various substation layouts have been con-sidered and are listed in Table III. These substation layouts havebeen arrived at with the modification of the terminal componentsfor the third switching configuration of the 245-kV GIS. For theCFG5 configuration, the load side of the switch CB3 is termi-nated with a long gas-insulated line ( km) and the source sideof the switch is terminated with an XLPE cable. The peak mag-nitude of the transient current in each cable for the second sub-station layout (CFG2) is less than that in the cable of the firstconfiguration. Fig. 5 shows the variation of the peak magnitudeof the transient current with distance for different substation lay-outs. From this figure, it is evident that the reduction in peakmagnitude of the transient current for the overhead line termi-nation (bushing) is more compared to the GITL and XLPE cableterminations. Nevertheless, the peak magnitude of the transientcurrent at the bushing is small compared to the other termina-tions of the GIS, the highest transient current level remainingunaltered. The peak amplitude of the transient current for thefifth substation layout (CFG5) is the lowest compared to theother substation layouts. This may be due to the presence ofGITL instead of high capacitance component (T1) on the loadside of the switch.

The attenuation of the transient current amplitude with timeat a particular location is found to depend on the switching con-figuration and the terminal component connected to the GIS.The attenuation rate is high if the GIS is terminated with lowimpedance systems, such as XLPE cable, and the attenuationrate is low if the GIS is terminated with high surge impedance


TABLE IVATTENUATION RATE OF TRANSIENT CURRENT AMPLITUDES WITH TIME

elements such as an overhead line. Similarly, if the GIS is ter-minated with a long length of GITL, there is a possibility of thetransient currents for a longer time duration.

The attenuation rate of the amplitude of VFTC with time hasbeen calculated at different locations of the GIS for the abovesubstation layouts and are listed in Table IV. For the purpose ofcomparison, the peak magnitude of the transient current at about2 s is considered as the base value. The attenuation rate of thetransient currents at a particular position in GIS is definedas follows:

% (2)

where is the peak magnitude of transient current for theentire time duration and is the peak magnitude of transientcurrent after 2 s of the strike between the switching contacts.The attenuation rate of the amplitude of the VFTC with the timeat the switch operated is more or less in the same range witha cable or a GITL termination on the source side and a powertransformer on the load side of the switch. The attenuation oftransient currents with time is low if the GIS is terminated withan overhead line (CFG4) on the source side of the switch. Inother words, there is a possibility of higher transient currents fora longer time duration. There is a considerable change in attenu-ation of the transient current amplitude at the GIS-cable junctionif the load side of the switch is terminated with GITL (CFG5)instead of a power transformer (CFG1). More clearly, the at-tenuation of transient current at the source side of the switchnot only depends on the source side termination but also on theload-side termination and vice versa.

In the second stage of the analysis, the fast Fourier transform(FFT) technique has been employed to identify the dominantfrequencies of the transient currents. The frequency spectrumhas been calculated by considering the VFTC waveform for thetime duration of 4 s. Fig. 6 shows the frequency spectrum ofthe VFTC at different locations of a 245-kV GIS during the firstswitching operation. From this figure, it is evident that the dom-inant frequency components of the VFTC at the switch DS1 areup to 150 MHz, except that there is a high-frequency componentof 238 MHz with considerable amplitude. The high-frequencycontent of the transient current may be due to the small lengthof the open-end sections near the switch operated as well as dueto the fast voltage collapse (a few nanoseconds) between theswitching contacts during its operation. Near the switch DS1,the highest frequency of 310 MHz is possible and this high-frequency component created locally is observed to attenuatewithin a small distance (a few meters) from its point of genera-tion. Similar observations have been made in the earlier experi-

Fig. 6. Frequency spectra of the VFTC for the first switching operation(normalized amplitude in arbitrary units).

mental works reported in the literature [1]. At the current trans-former location, the frequency components of the VFTC arenot dominant beyond 150 MHz except that there is a high-fre-quency component of 238 MHz with reduced amplitude. How-ever, there is a considerable reduction in the amplitude of the fre-


quency components of the VFTC above 50 MHz. Interestingly,the frequency components at the GIS-cable junction are dom-inant only up to 14 MHz where as the frequency componentsmaximum of 31.5 MHz appear with moderate amplitudes. Sim-ilarly, for the second switching operation, VFTC waveforms arerich with high-frequency content at or near the operated switch.From the results, it is understood that the dominant frequencycomponents at the switch DS3 are up to 140 MHz. However,there are high-frequency components with moderate amplitudesin the range of 200 to 300 MHz at or near the switch DS3. At thecurrent transformer location, the frequency components of theVFTC are limited to 130 MHz except a high-frequency com-ponent of 238 MHz. Even though the physical location of theCT for the second switching configuration is at a longer dis-tance from the switch operated than for the first switching con-figuration, high-frequency components have been observed forthe VFTC at CT during the second switching operation. Thismay be due to switching on a smaller length of bus section forthe SW2 configuration. At the GIS-cable junction, the highestdominant frequency components are up to 13 MHz only. To un-derstand the effect of high capacitance components such as thepower transformer on the frequency content, frequency spectrahave been obtained for the VFTC at various locations duringthe third switching operation and are shown in Fig. 7. Fromthe above figure, it is evident that the frequency content of theVFTC at or near the switch CB3 are dominant up to 95 MHz ex-cept that there are high-frequency components of 164 and 270MHz with moderate amplitudes. Interestingly, the highest pos-sible frequency component of the VFTC at the current trans-former is only 80 MHz. The dominant frequencies at CT arein the lower range for the third switching operation due to thepresence of the power transformer on load side of the switch. Atthe GIS-cable junction, the dominant frequencies of the VFTCare limited to 15.5 MHz. The following observations have beenmade from the frequency spectrum of the VFTC at various lo-cations during the above switching events:

1) The amplitude of the frequency components particularlyabove 10 MHz is observed to have significant attenuationwith distance depending on the switching configuration.

2) At most of the locations in a 245-kV GIS, the highestamplitudes are possible for frequencies of a) 5 MHzfor the first switching configuration, b) 3.5 MHz forthe second switching configuration, c) 1.5 MHz for thethird switching configuration. This frequency value isexpected to decrease with an increase in the length of thegas-insulated section of the switching configuration.

3) The high-frequency components in the range of 150 MHzand above attenuate within a few meters from the point ofgeneration (i.e., from the switch operated). The attenua-tion of amplitudes of high frequencies with distance fromthe switch changes with the switching configuration ofGIS.

The variation in the frequency spectrum of the VFTC withdistance has been analyzed for different switching operations inthe 245-kV GIS. Fig. 8 shows the variation in the highest dom-inant frequency component (only those frequency componentswhose amplitudes are at least 10% of the maximum possible

Fig. 7. Frequency spectra of the VFTC for the third switching operation.

amplitude) with distance. From this figure, it is clear that forthe third switching configuration, high-frequency componentsof the VFTC are damped out within a short distance from theswitch compared to the other two switching configurations. It


Fig. 8. Variation of highest dominant frequency component of the VFTC withdistance.

has also been observed that high-frequency components above200 MHz appear at most of the locations for the first and secondswitching configurations. More clearly, switching on or off asmaller length of the bus section generates relatively lower tran-sient current with very-high-frequency content and switching onor off of high capacitance components generates higher transientcurrents with a frequency content limited to 95 MHz.

To understand the effect of terminal component of the GISon the frequency spectrum of the VFTC, different substationlayouts have been considered for the study (Table III). Interest-ingly, the dominant frequencies of the VFTC at the switch op-erated are almost in the same range for all of the configurations(CFG1 to CFG4), except a slight shift in the frequencies. How-ever, the amplitude of dominant frequency components changeswith each configuration. This may be due to an appreciable dif-ference in peak magnitude and attenuation rate of the transientcurrent at all of the locations of the GIS for different substationlayouts. From the analysis, it has been observed that the domi-nant frequencies appearing at the GIS-cable junctions/gas-to-airbushing are always less than 16 MHz and the frequency compo-nents maximum of 31.5 MHz appear with moderate amplitudes.Further, the frequencies up to 74.5 MHz appear with very lowamplitudes. To establish the highest possible frequency com-ponent at the GIS-bushing junction, the transient currents arecalculated at the entrance of gas-to-air bushing for the first andsecond switching configurations (SW1 and SW2) by replacingXLPE cable with an overhead transmission line. The peak mag-nitude of the transient current at the bushing is about 2.01 kAand 1.16 kA for these configurations, respectively. Interestingly,the frequency components of the VFTC at this location duringSW1 operation are possible up to 150 MHz. The transient cur-rents of these frequency components generate radiated electro-magnetic (EM) fields, which leak out from the bushing through acomposite insulator housing and may interfere with the nearbycontrols. Similarly, the transient current of the frequencies inthe range of 130–150 MHz and sometimes as high as 238 MHzthrough the CT couple to the control cables by means of ei-ther radiated EM fields or the conducted coupling mechanisms.Finally, the transient EM fields due to VFTC with frequencycomponents up to 310 MHz appearing at or near the switchmostly leak out of the GIS through the nonmetallic flanges and

the viewing ports depending on the electrical dimensions. TheVFTC waveforms obtained in the present study could be used asthe excitation for the quantification of transient EM field emis-sion from different modules of GIS and, hence, will be helpfulin developing an electromagnetic-interfeence (EMI) chart for aparticular GIS installation.

IV. CONCLUSION

The peak magnitude of VFTCs generated during switchingevents changes from one position to another depending on theswitching operation in a 245-kV GIS. In the present paper, theparameters that characterize the VFTC have been analyzed. Thepeak magnitude of the transient currents at or near the switch op-erated could be in the range of 10 kA and dominant frequencycomponents are possible up to 270 MHz depending on the sub-station layout.

The peak magnitude of the transient current at the entranceof the gas-to-air bushing for most of the configurations of the245-kV GIS is about 1 kA. However, in a special situation suchas switching of a small length of the bus section with the switchlocated at a few meters distance from the bushing, the peak mag-nitude of VFTC could be about 2 kA and a frequency componentof even 150 MHz is possible. The peak magnitude of the tran-sient currents at the GIS-cable junction is in the range of 4 to9 kA, depending on the switching configurations or substationlayouts. The dominant frequencies of the VFTC at the GIS-cablejunction are less than 16 MHz and the frequency componentsmaximum of 31.5 MHz appear with moderate amplitudes. Theattenuation rate of the transient current with time and distanceis observed to be a function of the location of the switch beingoperated and the terminal component of the GIS. Switching onor off of smaller length bus sections (i.e., a few meters) results intransient current waveforms with dominant frequencies beyond200 MHz at most of the locations in a 245-kV GIS.

ACKNOWLEDGMENT

The authors are thankful to the management of BHEL andthe Indian Institute of Science for their permission to publishthe work. The first author would like to thank Dr. H. S. Jain forhis continuous encouragement and cooperation.

REFERENCES

[1] J. Meppelink, K. Diederich, K. Feser, and P. Pfaff, “Very fast transientsin GIS,” IEEE Trans. Power Del., vol. 10, no. 1, pp. 223–233, Jan. 1989.

[2] P. Clarenne, G. Ebersohl, J. Vigreux, and G. Voisin, “The effect of high-frequency transient regimes on secondary equipment in gas insulatedsubstations-design of earthing system, low voltage wiring, and elec-tronic equipment,” Electra, no. 126, pp. 95–116, Oct. 1989.

[3] A. M. Miri and Z. Stojkovic, “Transient electromagnetic phenomena inthe secondary circuits of voltage and current transformers in GIS (mea-surements and calculations),” IEEE Trans. Power Del., vol. 16, no. 4,pp. 571–575, Oct. 2001.

[4] C. M. Wiggins and S. E. Wright, “Switching transient fields in substa-tions,” IEEE Trans. Power Del., vol. 6, no. 2, pp. 591–600, Apr. 1991.

[5] C. M. Wiggins, D. E. Thomas, F. S. Nickel, T. M. Salas, and S. E.Wright, “Transient electromagnetic interference in substations,” IEEETrans. Power Del., vol. 9, no. 4, pp. 1869–1884, Oct. 1994.

[6] S. Nishiwaki, K. Nojima, S. Tatara, M. Kosakada, N. Tanabe, and S.Yanabu, “Electromagnetic interference with electronic apparatus byswitching surges in GIS—Cable system,” IEEE Trans. Power Del., vol.10, no. 2, pp. 739–746, Apr. 1995.


[7] M. M. Rao, M. J. Thomas, and B. P. Singh, “Frequency spectrum anal-ysis of fast transient currents (FTC) during switching operation in a 245kV GIS,” in Proc. IEEE/PES T&D Conf., Yokohama, Japan, Oct. 2002,pp. 2239–2243.

[8] S. Ogawa, E. Haginomori, S. Nishiwaki, T. Yoshida, and K. Terasaka,“Estimation of restriking transient overvoltage on disconnecting switchfor GIS,” IEEE Trans. Power Del., vol. PWRD-1, no. 2, pp. 95–102, Apr.1986.

[9] Z. Haznadar, S. Carsimamovic, and R. Mahmutcehajic, “More accuratemodeling of gas insulated substation components in digital simulationsof very fast electromagnetic transients,” IEEE Trans. Power Del., vol. 7,no. 1, pp. 434–441, Jan. 1992.

[10] P. Osmokrovic, S. Krstic, M. Ljevak, and D. Novakovic, “Influence ofGIS parameters on the Toepler constant,” IEEE Trans. Elect. Insul., vol.27, no. 2, pp. 214–220, Apr. 1992.

M. Mohana Rao was born in Guntur, India, in1973. He received the B.Tech. degree from SriVenkateswara University, Tirupathi, India, in 1994and the M.Sc. degree in engineering in 1996 fromthe High Voltage Engineering Department, IndianInstitute of Science, Bangalore, where he is currentlypursuing the Ph.D. degree.

Currently, he is a Senior Engineer with BharatHeavy Electricals Ltd. R&D, where he has beensince 1996. His research areas are the designand development of gas-insulated substations

(GIS), gas-insulated lines, electromagnetic-interference/electromagnetic-com-patibility (EMI/EMC) studies in GIS- and computational fluid dynamics(CFD)-based analysis of circuit-breaker (CB) arcs.

M. Joy Thomas was born in Kerala, India, onJuly 22, 1961. He received the B.Tech. degree inelectrical engineering from Institute of Technology,Banaras Hindu University, Varanasi, India, and theM.Sc. (Eng.) and Ph.D. degrees from the Departmentof High Voltage Engineering, Indian Institute ofScience, Bangalore, India.

Currently, he is an Assistant Professor with theDepartment of High Voltage Engineering, Indian In-stitute of Science, Bangalore. His research interestsare gas-insulated switchgear (GIS), electromag-

netic interference/electromagnetic compatibility (EMI/EMC), pulsed powerengineering, electrical transients in power systems, digital measurement ofhigh voltage, extra-high-voltage (EHV) power transmission, and insulationengineering.

B. P. Singh was born in Bihar, India, in 1947. Hereceived the B.E. degree in electrical engineeringfrom Muzaffarpur Institute of Technology, Bihar,India, in 1968, the M.E. degree in high voltage fromthe Indian Institute of Science, Bangalore, in 1971,and the Ph.D. degree from the Electrical EngineeringDepartment, University of Liverpool, Liverpool,U.K., in 1974.

He was a Postdoctoral Fellow at the Universityof Liverpool on a project sponsored by the UnitedKingdom Atomic Energy agency and thereafter for

two years at the Reactor Research Center, Kalpakkam, India. Currently, he isGeneral Manager of High Voltage, Gas Insulated Switchgear and AdvancedTechnical Education with Bharat Heavy Electricals Ltd., R&D, Hyderabad,India. He joined Bharat Heavy Electricals Ltd. in 1978. His research interestsare switchgear, high-voltage power transformers, motors, and capacitors. Hehas published many papers in various national and international journals andconferences.

very fast transients in gis

Documents