Analysis of Distribution, Pattern, and Vector of Electric Field in the Inter Phases Region of Three-phase Gas Insulated Switchgear

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1 International Journal on Electrical Engineering and Informatics - Volume 5, Number 4, December 2013 Phases egion of hree-phase Gas Insulated witchgear chool of Electrical Engineering and Informatics, Institut eknologi Bandung Jl. Ganesha 10 Bandung 40132, Indonesia umar@hv.ee.itb.ac.id Abstract: his paper deals with the electric field characteristics in the inter-phases region of three-phase gas insulated switchgear (GI). he electric field in a three-phase construction of a simplified GI model was analyzed. he results show that in the interphases region the direction and the magnitude of electric field vector varies with the location of the observation point while in the phase-enclosure region the direction of the electric field vector tends to linear and constant. here is no zero electric field on the particle tip of a particle in the inter-phases region, except 90 particle. here is zero electric field on the particle tip of a particle in the phase-enclosure region every half cycle of applied voltage. he maximum electric field of the particles on the inter-phases region generally is higher than one of the particles on the phase-enclosure region. he electric field vector locus in the inter-phases region varies: linear, elliptic, or circular while one in phase-enclosure region is constant and linear. Keywords: Electric field, inter-phases region, three-phase, GI, particle position 1. Introduction Discharge and breakdown phenomena in the insulation material under single-phase voltage are well-known and well established art. However, those in the insulation material under threephase voltage are far less understood [1-7]. In the other hand the application of three-phase power apparatus in the electric power system has been increasing. he design of three-phase in one tank such as three-phase power cable and three-phase gas insulated switchgear has been applied in the electric power system [8-9]. hree-phase in one tank power apparatus differs with single-phase one mainly in the configuration and the applied voltage. he differences result in the differences in the electric field between single-phase and three-phase equipment. Discharge is initiated by increase of the electric field in the part of insulation. herefore, knowledge in the three-phase electric field characteristic is useful for understanding discharge process in three-phase power apparatus. he characteristics of the electric field in three-phase equipment have been reported recently [10-15]. he rotating electric field and the elliptical nature of the electric field vector locus are the examples of special characteristics under three-phase voltage. he special characteristics mainly occur in the inter-phases region. herefore this paper discusses the electric field characteristics in the inter-phases region of three-phase power apparatus and the comparison with the electric field in the phase-tank or phase-enclosure region. 2. Model of hree-phase GI he GI model is arranged in isosceles triangle configuration as shown in Figure 1. he GI model consists of a tank model with 75mm in radius, 300mm in length, and 2mm in thickness; and three-phase conductor with 12.5 mm in radius. A cooper needle electrode was put on the conductor or on the tank an artificial partial discharge (PD) source. he particle radius was 50um. he particle length was 5mm. he particle position is normal to the surface of the conductor or the tank. he particle was put inside the tank at the middle of the tank. eceived: June 17 th, Accepted: December 2 nd,

2 Figure 1. Layout of GI model in isosceles triangle configuration he particle positions and their notations in the cross section of the tank are shown in Figure 2. Particle position is notated with a big character and an index in front of the character, P α. he character is used to explain the particle position at,, conductors or on the tank. Particle on,, conductor, and particle on the tank or on the enclosure (E) is notated as,,, and E, respectively. he index α is used to explain the particle position (in degree) relative to the positive x axis in the counter clock wise direction. For example, 270 means the particle at conductor, or from positive x axis. Figure 2. Particle position and notationn 3. Electric Field Analysis he electric fields inside the insulation of the construction were determined from a boundary element method simulation. he electric field calculation is two dimensional. he electric field on each particle tip was calculated at 1 kv applied voltage for the convenience of the comparison. A. he Electric Field Line in hree-phase GI Figure 3 shows electric field line inside three-phase GI in the presence of particle on 90 positions when the phase angle of phase of applied voltage θs=90 0. Here the maximumm electric field occurs around the conductor because the applied voltage on conductor is maximumm when θs=

It seems that the high intensity electric field line exist mainly in the inter phases region.

electric field vector tends to linear and constant. Figure 3.

he Electric Field Distribution in hree-phase GI Figure 4 shows the electric field distribution for several phasess of applied voltage. Here, θss is the phase angle of phase of applied voltage.

3 It seems that the high intensity electric field line exist mainly in the inter phases region. In the inter-phases region the direction and the magnitude of electricc field vector varies with the location of the observation point while in the phase enclosure region the direction of the electric field vector tends to linear and constant. Figure 3. he electric field line inside three-phase GI in the presence of particle on 90 positions when the phase angle of phase of applied voltage θs=90 0. B. he Electric Field Distribution in hree-phase GI Figure 4 shows the electric field distribution for several phasess of applied voltage. Here, θss is the phase angle of phase of applied voltage. he blue color reveals that the electric field intensity is the lowest, while the red color reveals that the electric field intensity is the highest. For θs = 90 o and θs = 180 o it seems that the electric field intensity in the phase-enclosuree region and inter phases region is almost the same. For θs = 120 o and θs = 240 o it seems that the electric field intensity in the inter phases region is higher than in the phase-enclosure region. he electric field distribution pattern varies with phase of applied voltage. θs=0 0 o θs=90 o θs=240 o θs=120 o Figure 4. he electric field distribution in three-phase constructionn 494

4 C. he Pattern of Electric Field on the Particle ip Figure 5-8 shows the pattern of the electric field on the particle tip of a particle set at various positions on,,, phase conductors or on the enclosure, respectively, during a cycle of applied voltage. 0, 315, 45, 90, 135, 180, 225 are the particles in the interphases region or the particles on the conductor facing to the other conductors. 180, 270, 0, E0, E90, E180, and E270 are the particles in the phase-enclosure region or on the conductor facing to the tank. he electric field intensity on each point inside the insulation varies with the phase of the applied voltage. he pattern variation is sinusoidal alike the applied voltage. he electric field achieves the minimum and the maximum values every a half cycle of applied voltage. he pattern of the electric field intensity is repetitive every a half cycle of applied voltage Phase Angle of Applied Voltage (degree) Figure 5. Periodic change of the electric field on the particle tip of a particle at phase conductor (0,315 are the particles in the inter-phases region; 180 is a particle in phase-enclosure region) Phase Angle of Applied Voltage (degree) Figure 6. Periodic change of the electric field on the particle tip of a particle at phase conductor (45, 90, and 135: particles in the inter-phases region; 270 is a particle in phase-enclosure region) 495

5 he characteristics of electric field on the tip of the particle on the,, and conductors are similar in the pattern and the magnitude of the electric field. here are differences in the electric field pattern and magnitude between a particle on the conductor and a particle on the tank. he electric field on the tip of a particle on the tank is lower than one on the tip of a particle on the conductor. he pattern of electric field on the tip of a particle on the tank always has zero electric field. he pattern of electric field on the tip of a particle on the conductor generally has no zero electric field Phase Angle of Applied Voltage (degree) Figure 7. Periodic change of the electric field on the particle tip of a particle at phase conductor (180, 225 are the particles in the inter-phases region; 0 is a particle in phase-enclosure region) E0 E90 E180 E Phase Angle of Applied Voltage (degree) Figure 8. Periodic change of the electric field on the particle tip of a particle at the enclosure For a particle in the interphases region, there is no zero electric field except 90 particle. For a particle in the phase-enclosure region, there is zero electric field every half cycle of applied voltage. he maximum electric field of the particles on the inter-phases region is higher than one of the particle on the phase-enclosure region. he intensity of the minimum and the maximum electric field depend on the particle position. It is considered to be caused by the dependence of the gap distance and the electrode configuration of the three-phase gas insulated switchgear on the particle position. Figure 9 summarizes the intensity of the minimum and the maximum electric field for a particle in the interphase and phase-enclosure regions. 496

Figure 10 summarizes the phase angle of applied voltage at maximum electric field for a particle in the interphase and phase-enclosure regions.

6 Figure 10 summarizes the phase angle of applied voltage at maximum electric field for a particle in the interphase and phase-enclosure regions. he phase angle of applied voltage at maximum electric field depends on the particle position for a particle in the interphase and phase-enclosure regions PHAE PHAE PHAE ENCLOUE Emax (kv/mm) Emin (kv/mm) Particle Position Figure 9. Maximum and minimum electric field on the particle tip at 1 kv applied voltage for particle in the inter-phase region and in the phase-enclosure region Phase Angle of Phase Applied Voltage at Maximum Electric Field PHAE PHAE PHAE ENCLOUE E0 E90 E180 E Particle Position Figure 10. Phase angle of applied voltage at maximum electric field for a particle in the interphase region and in the phase-enclosure region In general, the maximum electric field on the tip of a particle set on one phase conductor occurs on the peak of applied voltage at the related phase. he effects of the other phases take 497

7 place when the particle faces to another conductor, resulting in the shifting of the phase of maximum electric field from the peak of applied voltage. D. he Electric Field Vector in the Interphases egion of hree-phase GI It is reported in the previous paper that the electric field in three-phase GI rotates and changes continuously. he electric field vector locus may elliptic, linear, or circular. he elliptical nature of rotating electric field is expressed as electric field ratio (η). It is defined as the ratio of the minimum of electric field to the maximum electric field [10-12]. Figure 11 shows the elliptical nature of rotating electric field in the inter-phases region of three-phase GI. he observation points A to F are in the distance of 0 mm (A), 5 mm (B), 10 mm (C), 15 mm (D), 20mm (E), and 25 mm (F) away from conductor. he electric field ratio changes from η=0 (the electric field vector locus is linear) on the surface of conductor to η=, η=, η=0.7 D (the electric field vector locus is elliptic) at points B, C, and D), and to η=1 (the electric vector locus is circular) at point E. hese results differ with the results in phase-enclosure region. In phase-enclosure region the electric field vector locus always linear [10]. F η=0.8 E η=1 D η=0.7 C η= B η= A η=0 Figure 11. he electric field vector locus in the inter-phases region of three-phase GI 4. Conclusions his paper deals with electric field characteristics in the inter-phases region of three-phase gas insulated switchgear (GI). he electric field in a three-phase construction of a simplified GI model was analyzed. he following conclusions are drawn. In the inter-phases region the direction and the magnitude of electric field vector varies with the location of the observation point while in the phase enclosure region the direction of the electric field vector tends to linear and constant. here is no zero electric field on the particle tip of a particle in the inter-phases region, except 90 particle. here is zero electric field on the particle tip of a particle in the phase-enclosure region every half cycle of applied voltage. In general the maximum electric field of the particles on the inter-phases region is higher than one of the particle on the phase-enclosure region. he electric field vector locus in the inter-phases region varies: linear, elliptic, or circular while one in phase-enclosure region is constant and linear. 498

8 5. eferences [1]. Okabe,. Kaneko, M. Yoshimura, H. Muto, C. Nishida, M. Kamei, Propagation Characteristics of Electromagnetic Waves in hree-phase-ype ank from Viewpoint of Partial Discharge Diagnosis on Gas Insulated witchgear, IEEE ransactions on Dielectrics and Electrical Insulation, Vol. 16, No. 1, pp , [2], Nobuko Otaka, akakazu Matsuyama, Yoshiki akehara, hinya Ohtsuka, Masayuki Hikita, Examination of ingle Phase PDM Device for PD Diagnosis on hree-phase GI, International Journal on Electrical Engineering and Informatics, Vol. 2 No. 3, pp , [3] E. Harkink, F.H. Kreuger, P.H.F. Morshuis: Partial Discharges in hree-core Belted Power Cables, IEEE ransactions on Electrical Insulation, Vol. 24, No. 4, pp , [4],. Ohtsuka,. Matsumoto, M. Hikita, Partial Discharge and Cross Interference Phenomena in a hree-phase Construction, International Journal on Electrical Engineering and Informatics, Vol. 1, No.1, pp , [5] P.C.J.M. van der Wielen: On-line Detection and Location of Partial Discharges in Medium-Voltage Power Cables, Doctoral Dissertation,.U. Eindhoven, [6],. Ishitobi,. Ohtsuka,. Matsumoto, M. Hikita, Effect of Elliptical Nature of otating Electric Field on Partial Discharge Pattern in a hree-phase Construction, IEEJ ransaction on Fundamentals and Materials, Vol. 127, No.9, pp , [7], atoshi Matsumoto, hinya Ohtsuka, Masayuki Hikita, Partial Discharge Measurement in hree-phase Construction, IEEE International Conference on Properties and Application of Dielectric Material ICPADM 2006, Bali, Indonesia, [8]. Yanabu, Y Murayama, and. Matsumoto, F6 Insulation and its Application to HV Equipment, IEEE ransactions on Electrical Insulation, Vol. 26, No.3, pp , [9]. Yanabu, H. Okubo,. Matsumoto: Metallic Particle Motion in hree-phase F6 Gas Insulated Bus, IEEE ransactions on Power Delivery Vol. PWD-2, No. 1, pp. 1-6, January [10], Electric Field Characteristics under hree-ohase Voltage in hree-phase Gas Insulated witchgear, International Journal on Electrical Engineering and Informatics, Vol. 4, No.3, pp , October [11], otating Characteristicsof Electric Field Vector in hree-phase Power Apparatus, IEEE Conference on Condition, Monitoring, and Diagnosis, Bali, Indonesia, eptember [12], Locus and Pattern of Electric Field Vector in the Insulation of hreephase Gas Insulated witchgear, IEEE International Conference on Power Engineering and enewable Energy, Bali, Indonesia, July [13] N.H. Malik, A.A. al-arainy, Electrical tress Distribution in hree-core Belted Power Cables, IEEE ransactions on Power Delivery, Vol. PWD-2, No. 3, pp , July [14], Electric Field Characteristics inside hree-phase Gas Insulated witchgear in the Presence of Foreign Metallic Particle International Conference on Electrical Engineering and Informatics, Malaysia, June [15], Analysis of Electric Field in the Inter Phases egion of hree-phase Gas Insulated witchgear, International Conference on ural Information and Communication ecnology and Electric Vehicle, Indonesia, November

Umar Khayam is an Assistant Professor at chool of Electrical Engineeringg and Informatics, Institut eknologi Bandung (IB), Indonesia. He was born in urakarta, Indonesia in 1975. He received the B.Eng. (cum laude) and M.

9 Umar Khayam is an Assistant Professor at chool of Electrical Engineeringg and Informatics, Institut eknologi Bandung (IB), Indonesia. He was born in urakarta, Indonesia in He received the B.Eng. (cum laude) and M.Eng. degrees in electrical engineering from IB in 1998 and 2000, respectively. He received the Dr. Eng degree in electrical engineering from Kyushu Institute of echnology (KI), Japan in He worked as a esearcher at Hikita Laboratory, KI during and Currently he is the Head of High Voltage and High Current Engineeringg Laboratory, IB. Dr. is the General ecretary of 2012 IEEEE International Conference on Condition, Monitoring, and Diagnosis (CMD). He received Best Paper Award in 2005 Korea Japan ymposium on High Voltage Engineering and Electrical Discharge. His research interest is partial discharge measurement and phenomena in electric power apparatus. Dr. Umar Khayam is a member of IEEE. 500

Electric Field Characteristics under Three-phase Voltage in Three-phase Gas Insulated Switchgear

International Journal on Electrical Engineering and Informatics Volume 4, Number 3, October 2012 Electric Field Characteristics under Three-phase Voltage in Three-phase Gas Insulated Switchgear Umar Khayam