I. INTRODUCTION II. MULTICHAMBER SYSTEM (MCS) A. MCS Principle

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1 214 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 26, NO. 1, JANUARY 2011 Overhead Lines Lightning Protection by Multi-Chamber Arresters and Insulator-Arresters Georgij V. Podporkin, Senior Member, IEEE, Evgeniy Yu Enkin, Evgeniy S. Kalakutsky, Vladimir E. Pilshikov, and Alexander D. Sivaev Abstract Reported are results of research and development of multi-chamber arresters and insulators that combine characteristics of insulators and arresters. The devices permit to protect overhead power lines rated at 3 to 35 kv and above against induced overvoltages and direct lightning strokes without using shield wire. Index Terms Insulators-arresters, lightning protection, multichamber arresters, overhead power lines, power arc. I. INTRODUCTION L IGHTNING protection of overhead lines by multiple sparkover gaps has a long history. For example, gear-type arresters (those with multiple parallel gaps) were developed in 1886 for protection of a 2-kV telegraph system [1]; several series gaps installed at overhead power line poles were suggested in [2], etc. The main problem of these solutions was their limited quenching ability. They were found to be inefficient at high values of power follow current. A unique device comprising metal pads laid over the surface of a wooden pole or crossarm, a so-called Darverter [3] did improve the quenching ability owing to gas generating properties of wood but its application area was limited to overhead lines with wooden crossarms or poles. Multigap systems are successfully used in combination with a series nonlinear resistor in well-known silica carbide (SiC) arresters [4] for the protection of substation equipment; however, because these gapped arresters cannot withstand direct lightning strokes, they are not as suitable for lightning protection of overhead lines. Multigap systems are also used as diverters on fiberglass radomes (protective housings for aircraft radar antennae) [5]. Long flashover arresters with a multielectrode system based on the creeping discharge effect were proposed in [6]. While they can be used for lightning protection of medium-voltage (MV) overhead lines, their fairly large dimensions make them unsuitable for high-voltage (HV) applications. Over recent years, the authors of this paper have been active in developing arresters with a multichamber system (MCS), succeeding in the production of new 10- to 35-kV arresters as well as a novel device called a multichamber insulator arrester Manuscript received April 05, 2010; revised June 13, 2010; accepted July 19, Date of publication October 28, 2010; date of current version December 27, Paper no. TPWRD The authors are with the Streamer Research and Production Company, St. Petersburg , Russia ( georgij.podporkin@streamer.ru). Color versions of one or more of the figures in this paper are available online at Digital Object Identifier /TPWRD (MCIA), which combines the properties and functions of the arrester and insulator. The application of MCIAs makes it possible to ensure lightning protection of overhead lines of any voltage ratings: the higher the line voltage is, the larger the number of units in a string and, thus, the higher the rated voltage and the arc-quenching capacity are of a string of insulator arresters. Various designs of insulators with arrester properties are possible. An MCIA is generally a production glass, porcelain, or composite insulator fitted with an MCS. The installation of an MCS confers arrester properties to the insulator without any deterioration of its insulating capacity. For this reason, the application of MCIA on overhead lines makes shield wire redundant, while the height, weight, and cost of poles or towers goes down. At a lower overall cost and with better lightning performance, this line features a noticeably reduced number of lightning failures, cuts damage from the undersupply of energy, and lowers maintenance costs. MCIAs hold much promise in the protection of railway overhead contact systems against direct lightning strokes (DLS). A. MCS Principle II. MULTICHAMBER SYSTEM (MCS) The base of multichamber arresters (MCA), including MCIA, is the MCS shown in Fig. 1. It comprises a large number of electrodes mounted in a length of silicon rubber. Holes drilled between the electrodes and going through the length act as miniature gas discharge chambers. When a lightning overvoltage impulse is applied to the arrester, it breaks down gaps between electrodes. Discharges between electrodes occur inside chambers of a very small volume; the resulting high pressure drives spark discharge channels between electrodes to the surface of the insulating body and, hence, outside into the air around the arrester. A blow-out action and an elongation of interelectrode channels lead to an increase of the total resistance of all channels (i.e., that of the arrester), which limits the lightning overvoltage impulse current. B. Experimental Samples, Test Facility and Test Procedure A large number of MCAs featuring different shapes of steel electrodes were tested (see Fig. 1), including 8-mm-diameter and 2 mm-thick washers; 10-mm-long and 2-, 3-, and 4-mm diameter pieces of steel rods, and 10-mm diameter balls. Intermediate electrodes were spaced 0.5 to 2 mm apart. The diameter of chamber openings varied from 2 to 5 mm, while the chambers were 1 to 5 mm deep. The most interesting results /$ IEEE

2 PODPORKIN et al.: OVERHEAD LINES LIGHTNING PROTECTION BY MULTI-CHAMBER ARRESTERS AND INSULATOR-ARRESTERS 215 Fig. 1. Multichamber system (MCS): (a) Diagram showing the discharge onset instant. (b) Diagram showing the discharge end instant. (c) Tests of MCS helically wound around 50-mm diameter cable: 1) silicon rubber length, 2) electrodes, 3) arc quenching chamber, and 4) discharge channel. Fig. 2. Circuit diagram of test facility. C = 700 F; L = 14 mh; L = 2.7 mh; R = ; L = 0.2 mh; C = 50 nf; R = 0.01 ); C = 1000 pf; C 1000 nf(c =C 1000), R = }, C =0:5 F. were obtained for the MCA with ball-shaped intermediate electrodes; for this reason, a bulk of findings is reported further for this MCA design. In order to determine the follow-up current quenching efficiency of MCS, use was made of a test setup including a 50-Hz oscillator and a high-voltage lightning impulse generator. The circuit diagram of the test facility is shown in Fig. 2. To make the test MCS operate, a 250-kV output impulse generator was connected to the arrester across the resistance. The alternating voltage was generated by a capacitance-inductance oscillatory circuit with an oscillation frequency close to 50 Hz. Energy was first stored in a 700- F capacitor bank at. The power frequency voltage was ensured by the oscillatory circuit, by operation of the arrester actuated by the overvoltage impulse from the impulse generator. The test MCS was connected to the 50-Hz oscillator across the resistor and the reactor. The reactor was used to disconnect the capacitor from the MCS at the instant of arc quenching at voltage recovery frequencies. The resistor simulated resistance in the arrester circuit on the line, for instance, the pole footing resistance. Tests were carried out for two values of and 10. The value 0 corresponds to a case of direct lightning stroke to an overhead line and to phase-to phase short circuit (see Fig. 12), while 10 corresponds to the indirect lightning stroke (i.e., to induced overvoltages and flashover of arresters installed at different poles and different phases at an overhead line of MV) (e.g., 10 kv). The voltage recovery frequency was set by the coil and the capacitor. The design voltage recovery frequency was set at 50 khz for a 60- impedance of the circuit MCS,,. MCS current and voltage were measured and recorded with the help of the capacitance voltage divider, the current shunt resistor, connecting cables, and a digital memory oscilloscope. The test procedure was as follows: first, the capacitor bank and the impulse generator were charged; operation of the impulse generator led to the breakdown of the test MCS and the auxiliary arrester. Thus, a lightning overvoltage impulse and the ac voltage were applied to test the MCS simultaneously. As the lightning overvoltage impulse ends, only the power frequency voltage remains applied to the arrester. Voltage and current oscillograms were recorded during the tests (see Fig. 3). Fig. 3(b) also presents additional computer oscilloscope patterns of arc dynamic resistance obtained by dividing the digital oscilloscope pattern of voltage by the oscilloscope pattern of current. Studies have shown that spark discharge quenching can take place in two instances: 1) when the instantaneous value of lightning overvoltage impulse drops to a level equal to or larger than the instantaneous value of power frequency voltage (i.e., the lightning overvoltage current gets extinguished with no follow current in the grid (this type of discharge quenching is further referred to as impulse quenching [see Fig. 3(a)] and 2) when 50-Hz follow current crosses zero (this type of discharge quenching is further referred to as zero quenching [see Fig. 3(b)]. The most common test procedure was as follows. First, the capacitor bank was charged to a certain level corresponding to the grid voltage crest value [see Fig. 3(a)]. The aforementioned procedure was further used throughout the test, and the resulting voltage and current oscilloscope patterns served as the basis for recording quenching or non-quenching findings. In the quenching case, the voltage was raised to the next step (generally 1 kv) and the test was continued until the non-quenching stage. Further, after non-quenching, the voltage was lowered by a half-step (generally by 0.5

3 216 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 26, NO. 1, JANUARY 2011 Fig. 4. Oscilloscope patterns for MCS with different electrode numbers m: 1 50; 2 100; It was shown by the tests that quenching occurs in impulse at low values of but in zero as increases. Fig. 3. Voltage, current, and resistance oscillograms in power follow current quenching tests of MCS m =100: (a) Impulse quenching. (b) Zero quenching t 0 application of ac voltage and lightning impulse, t 0 quenching of lightning impulse, and t 0 quenching of power follow current. kv) and the test was repeated. The highest value of was assumed to be the final quenching crest value of grid voltage. In case of impulse quenching [Fig. 3(a)], the respective effective phase voltage of the grid is found as. In the zero quenching case, is, where is the crest voltage of the second half-cycle. C. Test Results Of interest is the fact that at impulse quenching [Fig. 3(a)] and at zero quenching Fig. 3(b)], voltage does not get chopped to zero, as occurs in standard rod-plane and rod-rod gaps, and considerable residual voltage exists. At zero quenching, this residual voltage is a voltage drop in the arc channel, while at impulse quenching, it is a voltage drop in the spark discharge channel. Fig. 4 shows oscilloscope patterns obtained for various numbers of MCA electrodes; Fig. 5 displays the minimum residual voltage on the arrester versus the number of electrodes at positive and negative polarities of the applied voltage impulse. The tests were carried out for three resistance values of the series-connected generator ( 100, 200, and 700 ). As shown in Fig. 5, the residual voltage grows linearly with the increase of the number of MCS chambers and virtually does not depend on ; in other words, does not depend on the impulse current over a range from 0.4 to 3 ka, characteristic of induced overvoltages. Fig. 6 presents the voltage current characteristic for an MCS with 40 obtained from Fig. 3(b). The characteristic is seen to be highly nonlinear, exhibiting a fairly sharp arc voltage drop. With current varying from 1000 A to 2500 A, residual voltage remains near constant at 2.6 kv. As seen from Fig. 5, the minimum residual voltage Ures increases linearly with the number of chambers m. For 100, Ures is around 6.5 kv; for a larger number of m (e.g., 1000), Ures would be about 65 kv. It means that power follow current will be sufficiently limited, with arc quenching becoming more efficient. Fig. 7 shows the experimental values of grid voltage in which follow current is quenched versus the number of MCS chambers. The data of Fig. 7 make it possible to estimate the necessary number of MCS channels for the arresters of different voltage classes. MCSs underwent electrodynamic stability tests using 4/10 mcs 65 and 100 ka (max) current impulses. MCS prototypes withstood five exposures to 65-kA impulses or two exposures

4 PODPORKIN et al.: OVERHEAD LINES LIGHTNING PROTECTION BY MULTI-CHAMBER ARRESTERS AND INSULATOR-ARRESTERS 217 Fig. 7. Follow current-quenching grid voltage versus the number of MCS chambers: 1) impulse quenching (instantaneous value) ; 2) zero quenching at R = 0 (effective value) ; 3) zero quenching at R =10(effective value). Fig. 5. Minimum residual voltage versus the number of MCS electrodes: 1 U at impulse quenching at different generator resistances R : 0100 ; ; ; 2 U at zero quenching and R = 0. Fig. 6. Voltage current characteristic of of MCS m = 40 [obtained from Fig. 3(b)]. Fig. 8. The 10-kV multichamber arrester MCA-10-I for protection against induced overvoltages. to 100-kA impulses, which proves that MCSs can withstand an electrodynamic impact at DLS. III. MULTICHAMBER ARRESTERS (MCAS) A. MCA kv The principal components of a kV MCA (see Figs. 8 and 9) are an MCS, a fiberglass bearing rod, and an assembly for securing arresters to insulator pins. Arresters are mounted on insulator pins with air gaps of 3 to 6 cm between the top ends of the arresters and the conductor. A lightning overvoltage first breaks down the air spark gap, followed by the arrester s MCS, which ensures the extinction of follow current as described in Section II. Fig. 8 shows an arrester with 20 gas discharge chambers intended for the protection of 10-kV overhead lines (12 kv max.) against induced overvoltages. One piece of this model is installed on each phase-interlacing pole (Fig. 10). In this case, the path of ac follow currents that are associated with lightning overvoltage induced multiphase includes the tower-grounding resistance circuits. Thanks to an extra resistance of the pole grounding circuit, follow currents are made lower, which raises the quenching efficiency of the arrester. For principal performance data, see Table I. Shown in Fig. 9 is an arrester with 40 gas discharge chambers (see Table I). It can be used on 10-kV overhead lines for DLS protection and on 20-kV (24 kv max.) lines to fight induced overvoltages. In the latter case, the aforementioned 10-kV procedure has proved practical, with one arrester installed on each phase-interlacing pole (Fig. 11). A direct lightning stroke on a kv medium-voltage (MV) line causes a flashover of insulators of all three phases on one or several poles. To warrant reliable DLS protection,

5 218 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 26, NO. 1, JANUARY 2011 TABLE I ARRESTER PERFORMANCE DATA Fig. 9. Multichamber arresters for DLS protection of 10-kV lines and induced overvoltage protection of 20-kV lines. Fig. 11. Arrester arrangement for protection against induced overvoltages. Fig. 10. Multichamber arrester for 20-kV DLS protection (MCA-20-DLS). arresters should be installed in parallel with each insulator of the line (or those line sections that should be protected against DLS (see Fig. 12). About 1800 arresters of this type (Fig. 9) were installed at 6-kV overhead power lines of Lukoil Oil Company (Russia) in March Tests of the arrester with a 3-cm conductor-arrester air gap (Fig. 9) have shown its 50% sparkover voltage to remain practically unchanged at about 85 kv after ten zero quenchings. Fig. 10 shows an arrester with 120 discharge chambers designed for DLS protection of 20-kV lines (see Table I). Its operating principle and installation procedure are similar to those described before (see Fig. 12). Fig. 12. Arrester arrangement for protection against direct lightning strokes. B. MCA-35 kv This MCA consists of an MCS, its bearing component, and a composite insulator with discharge rods assuring an air spark gap (see Fig. 13). The bearing component is a piece of polyethylene-covered cable with a fiberglassplastic core and metal terminals. The outside diameter of the cable is 50 mm. The cable cover consists of a thick inner layer of insulating polyethylene and a 2-mm outer layer of light-stabilized, trekking-resistant polyethylene. The 8-mm diameter fiberglass plastic rod is

6 PODPORKIN et al.: OVERHEAD LINES LIGHTNING PROTECTION BY MULTI-CHAMBER ARRESTERS AND INSULATOR-ARRESTERS 219 Fig. 13. Illustration of MCA 35 kv on the tangent tower: (1) tower, (2) insulator, (3) line conductor, (4) MCS, (5) bearing component, (6) composite insulator, (7) discharge rods, and (8) arrester s grounding conductor. press-fitted into the terminals. The design ensures a high mechanical strength of the arrester. MCS is spiraled around the bearing component. An overvoltage on a line conductor caused, for instance, by a DLS (see Fig. 13), first triggers an air spark gap between discharge rods on the composite insulator followed by the MCS. The lightning overvoltage current flows through the arrester s grounding conductor to the tower and then to the ground. Excellent discharge-quenching characteristics of the MCS warrant either zero or impulse extinction of the overvoltage current and the power transmission line keeps working without failure. The principal performance data of the 35-kV MCS are shown in Table I. Fig. 19 shows a photograph of a commercial 35-kV overhead line of the Kamyshin Grid of Volgogradenergo Utility (Russia) with two MCS installed on its outer phases. IV. MULTICHAMBER INSULATOR ARRESTERS (MCIA) Fig. 14 features photos of an MCIA based on a porcelain rod insulator which is widely used in 3-kV dc railway overhead contact systems. The MCS is mounted over three quarters of the circumference of an insulator shed. The left and right ends of the MCS are approached by the upper and lower feed electrodes, respectively, which are installed on the upper and lower terminals; there are spark air gaps between the feed electrodes and the ends of the MCS. When the MCIA is stressed by an overvoltage, the air gaps get sparked over first, and the MCS comes next. The lightning overvoltage current flows from the lower terminal and its feed electrode via the spark channel of the lower spark gap to the MCS and on to the upper terminal via the discharge channel of the upper spark gap and the upper feed electrode. Note that there are no intervening electrodes between the upper and lower feed electrodes on the MCS-bearing silicon rubber shed; thus, the discharge develops over the MCS, taking some three quarters of the shed s circumference, rather than between the feed electrodes. A direct lightning stroke on the contact system or on its support brings about a sparkover, as described before. After the lightning overvoltage is over, with its current directed to the Fig. 14. Multichamber insulator arrester based on the porcelain insulator used in 3-kV dc railway overhead contact systems. (a) MCIA photo: (1) insulating body, (2) upper terminal, (3) lower terminal, (4) upper feed electrode, (5) lower feed electrode, (6) multichamber system, (7) upper spark discharge gap, and (8) lower spark discharge gap. (b) Tests of MCIA. Fig. 15. The 20-kV multichamber insulator arrester based on the SDI-37 insulator. ground via the support with the help of the MCS, an impulse extinction of the discharge occurs without any follow current, so that the contact system keeps working without outage. Fig. 15 shows a multichamber insulator arrester based on the SDI-37 pin insulator. It functions very similar to the MCIA shown in Fig. 14, but it is intended for protection of 6 10 kv lines against DLS and 20-kV lines against induced overvoltages. Fig. 16 shows a multichamber insulator arrester based on the glass cap-and-pin insulator type U120AD (MCIA-U120AD), during power follow current extinction tests with zero quenching. Fig. 17 shows a photo of an MCIA string during lightning impulse tests. With an overvoltage applied to a conductor as well as to the lower feed electrode closest to the conductor, the lower spark discharge gap gets broken down and voltage gets applied to the MCS (the left side of it is in Fig. 17). The MCS gets actuated, the upper spark air gap between the right end of the MCS and the upper feed electrode gets flashed over, voltage is fed to the second insulator, and so it goes on. After all, the MCIA of the string has been actuated, the lightning overvoltage current flows via the tower to the ground,

7 220 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 26, NO. 1, JANUARY 2011 Fig. 16. tests. MCIA with insulator U120AD during power follow current extinction Fig. 18. Commercial 35-kV overhead line (Kamyshin Grid, Volgogradenergo Utility) with the MCS on outer phases and MCIA on the central phase. TABLE II TESTS OF 220-kV MULTICHAMBER INSULATOR-ARRESTER STRINGS (MCIAS-220) Fig. 17. Photo of a three-mcia string during lightning impulse tests: (1) sheds of the insulating body, (2) cap, (3) pin, (4) upper feed electrode, (5) lower feed electrode, (6) multichamber system, (7) upper spark discharge gap, (8) lower spark discharge gap, and (9) conductor. followed, however, by ac power follow current. At the zero crossing, the arc is extinguished and the line keeps operating without outage or reclosure. In March 2009, a batch of 300 MCIAs-35 kv was installed for prototype operation in the Kamyshin Grid Area of the Volgogradenergo Utility (Fig. 18). Federal Grid Co., which is the sole owner of all overhead power lines rated at 220 kv and above in Russia, is interested in the MCIA technology and organized a 220-kV line R&D program. Table II gives a list of tests fulfilled on strings of 14 MCIAs. MCIAs-220 have successfully passed all of the tests listed in Table I. The test results will be reported at a later stage. V. CONCLUSION 1) Multichamber systems (MCSs) have been developed that ensure quenching of discharge that follows a lightning overvoltage impulse. 2) MCSs make it possible to develop simple, inexpensive, and efficient arresters. 3) In 3-kV dc railway overhead contact systems, MCSs quench discharge immediately after a lightning overvoltage impulse with no follow current. 4) MCIAs have been developed, comprising production insulators and MCSs that are mounted over the perimeter of the insulating body without adversely affecting the insulating properties of insulators. 5) In principle, the application of MCIAs can warrant reliable protection of overhead lines of any rated voltage against induced overvoltages and direct lightning strokes. 6) Further research-and-development work that would include complex electric, mechanical, and climatic tests, as well as experimental field exploitation is expedient. REFERENCES [1] C. R. Morey and T. C. Oehne, Jr, Lightning arresters and schemes for testing, B.S. thesis, Armour Inst. Technol., Paul V. Galvin Libr., Ill. Inst. Technol., [2] A. O. Austin, Transmission line, U.S , Mar. 1, [3] M. Darveniza, A Lightning Protective Device for Overhead Lines Using the ARC Quenching Properties of Wood. Brisbane, Australia: Univ. Queensland, [4] Non-Linear Resistor Type Gapped Surge Arresters for A/C. Systems, , IEC Std [5] R. E. Baldwin, Lightning protection for aircraft radomes, U.S , Apr. 22, [6] G. V. Podporkin, V. E. Pilshikov, and A. D. Sivaev, Development of long flashover arresters with multi-electrode system for lightning overvoltage and conductor-burn protection of 6 to 35 kv overhead lines, in Proc. 28th Int. Conf. Lightning Protection, 2006, pp

8 PODPORKIN et al.: OVERHEAD LINES LIGHTNING PROTECTION BY MULTI-CHAMBER ARRESTERS AND INSULATOR-ARRESTERS 221 [7] G. V. Podporkin and E. S. Kalakutsky, Lightning arrester and overhead power line equipped with the arrester, Russia PCT/RU2009/000006, [8] G. V. Podporkin, High voltage insulator and overhead power line using the insulator, Russia PCT/RU2009/000142, Evgeniy S. Kalakutsky was born on August 8, He received the D.S. and M.S. degrees from the St. Petersburg State Polytechnic University in Currently, he is an Engineer with Streamer Research and Production Company, St. Pertersburg, Russia. Georgij V. Podporkin (SM 94) was born on August 26, He received the B.S., Ph.D., and D.Sc. degrees in electrical engineering from the St. Petersburg Technical University, St. Petersburg, Russia, in 1973, 1977, and 1990, respectively. From 1973 until 1991, he was a Research Scientist at the Extra High Voltage Laboratory of the St. Petersburg Technical University. During , he was a Scientific Consultant at CEPEL, Rio de Janeiro, Brazil. His fields of interest are lightning protection and insulation of overhead transmission and distribution lines. Currently, he is Director of Research at the Streamer Research and Production Company and a Part-Time Professor at the St. Petersburg Technical University. Vladimir E. Pilshikov was born on January 24, He received the B.S. and Ph.D. degrees in electrical engineering from the St. Petersburg Technical University, St. Petersburg, Russia, in 1973 and 1979, respectively. Since 1973, he has been a Research Scientist at the High Voltage Department of the St. Petersburg Technical University in the field of internal and external insulation of high voltage apparatus. Evgeniy Yu Enkin was born on April 7, He received the B.S. degree from the St. Petersburg State Communication Lines University (Electromechanical Department) in Currently, he is an Engineer with Streamer Research and Production Company. Alexander D. Sivaev was born on July 22, He received the B.S. and Ph.D. degrees in electrical engineering from St. Petersburg Technical University, St. Petersburg, Russia, in 1978 and 1999, respectively. From 1981 until 1995, he was a Research Scientist at the Extra High Voltage Laboratory, St. Petersburg Technical University, in the field of insulation and lightning protection of overhead transmission lines. Currently, he is Technical Director of the Streamer Research and Production Company.