INDEX:

I.N. Poluyanova

Abstract:

A combined conditioning and test method suitable for the estimation of the dielectric strength of commercial vacuum interrupters has been offered. A comparison with the conventional "up and down" method has been provided. This method has been successfully applied to a range of commercial vacuum interrupters.

S.V. Sydorenkov, A.S. Baturin, E.P. Sheshin

Abstract:

A new method of pressure dynamics registration in vacuum circuit breakers (VCBs) is described. It is based on dependence of field emission parameters on the pressure in VCB. It was noticed that the position of current-voltage characteristic in the Fawler-Nordheim (F-N) coordinates depends on the pressure in the vacuum chamber. Having made some assumptions we could register pressure dynamics by registering the change of current-voltage characteristic's intercept calculated at constant slope. This value was named the A_ -parameter. On measuring dependence of the A_ -parameter on time during a comparatively short period, one can forecast the alteration of the pressure in vacuum interrupter for a long time period.

A.M. Chaly, John Cunningham

Abstract:

A range of new products emerging from a recent development in vacuum switching technology is presented. Their technical characteristics, as well as particular benifits provided for customers, are discussed.

A.M. Chaly, A.A. Logatchev, K.K. Zabello, S.M. Shkol'nik.

Abstract:

The distribution of the spots over the cathode of high-current vacuum arc stabilized by axial magnetic field (AMF) has been investigated. AMF configuration has been varied from the conventional "bell-shaped" to "magnetic barrier", where substantial AMF is created in the electrode edge virtually vanishing in the center. The complex effect of the AMF configuration on the behavior of cathode spots has been found. This behavior has been satisfactory explained based on the Steenbeck principle. It has been shown that "magnetic barrier" represents optimum AMF configuration providing even current distribution and minimum arc voltage.

A.M. Chaly, L.V. Denisov, V.N. Poluyanov, I.N. Poluyanova

Abstract:

It has been found out that NSDD probability increases at cable/line charging current interruption compared with no-load test. This fact has been explained by the formation of contact welds at the closing of the preliminary charged cable/line. These welds being torn apart at the following contact partition may serve as a source of macroparticles or surface irregularities resulting in increased probability of NSDD.

K.K. Zabello, Yu.A. Barinov, A.M. Chaly, A.A. Logatchev, S.M. Shkol'nik

Abstract:

This experimental study dealt with cathode spot motion and the burning voltage of a low-current vacuum arc with electrodes of HCOF Cu and with a composition of CuCr30, subjected to a magnetic field. Arcs with current of I = 30 A burned in axial and transverse fields as well as with the induction vector inclined at an angle 5°< φ < 65° to the cathode surface. Butted-end electrodes were used with diameter 30 mm and gap h = 4 mm. The field components, axial Bn and transverse Bt, were varied independently over a wide range. The superposition of a transverse magnetic field on the arc was found to considerably increase both the constant component and noise level of the voltage U. If this arc is also superposed with an axial field, both the constant component and noise level decrease.

A.M. Chaly, A.T. Chalaya

Abstract:

A computer program has been elaborated to calculate switching overvoltages during transformer interruption of a magnetizing current by a vacuum circuit breaker (VCB). This program uses the Monte Carlo simulation technique and takes into account a three-phase switching phenomena in an isolated neutral electric circuit.

V.P. Afanas'ev, A.M. Chaly, A.A. Logatchev, S.M. Shkol'nik, K.K. Zabello

Abstract:

The images of the cathode, obtained by the method of high speed photography, are of ellipsoidal form as they are taken at a small (about 10 degrees) angle to the cathode surface. For this reason it is very difficult, if possible at all, to draw conclusions about the spatial distribution of cathode spots and current density over the cathode surface. One can perform inverse parallel projection, but first it is necessary to clean the image from the noise occurring from the plasma radiation and from other noise sources. In this paper we propose the method of image filtering, based on contours of equal intensity evaluation and subsequent estimation of the current density on the cathode.

A.M. Chaly, A.A. Gusev

Abstract:

Today vacuum circuit breakers (VCB) have become dominant apparatuses for a wide range of electrical networks with rated voltages of 6-36 kV. It is a matter of fact that a portion of this kind of switching devices for these voltage classes within the total amount of produced circuit breakers in Europe and USA is about 70%, in Japan is 100% and in 1997 in Russia this fraction outreached 50%.

A.M. Chaly, A.T. Chalaya, V.N. Poluyanov, I.N. Poluyanova

Abstract:

HF interruption behaviour of VCB is very important for the analysis of switching surges induced at the interruption of an inductive load by VCB. In an actual network, HF current is produced when the power cable is discharged through VCB separating contacts. Many researchers dealt with this problem by simulating actual cable by LC circuit with lumped elements. We have conducted experimental research concerning HF interruption behaviour of VCB with CuCr contacts at interruption of the cable and equivalent single-frequency LC circuit. The experimental results revealed a strong effect of cable stray parameters on the VCB HF interruption behaviour.

A.M. Chaly, A.T. Chalaya, V.N. Poluyanov, I.N. Poluyanova

Abstract:

A computer aided model has been used to simulate current chopping behaviour at different current levels. This model is based on the known arc life time of a DC current. The appropriate experimental research has been carried out for a batch of 35 industrial VI with CuCr contacts. The obtained dependencies of the average arc life time VC current shows a certain technological scatter that has been taken into account in further chopping current simulations. The developed software has been used to analyze features of 0.4kV motor interruptions by low voltage vacuum contactor with CuCr and AgWC contacts (low-surge contact material). The obtained results have been generalized in that they allow us to consider the necessity of the surge suppression when a low voltage vacuum contactor is applied for motor control.

A.M. Chaly, A.T. Chalaya

Abstract:

A computer program has been developed for simulating voltage escalation (VE) when a vacuum circuit breaker (VCB) interrupts a starting motor. The influences of the vacuum circuit breaker's high frequency (HF) interrupting capability, dielectric strength rise, cable length and also, motor power, has been traced out to produce a sort of general view of the overvoltage phenomena in actual networks. It has been discovered that HF interrupting capability is important for high power motors connected by short cables to the VCB when B-termination of VE predominates. In the majority of practical cases, overvoltage protection is recommended for both conventional and low surge contact materials.

A.M. Chaly, A.T. Chalaya, V.N. Poluyanov, I.N. Poluyanova

Abstract:

The Monte-Carlo simulating technique and appropriate software has been developed to analyze switching overvoltages occurring at the interruption of 6 and 10 kV motors by VCB with CuCr contacts. VCB parameters have been determined experimentally. A comparison has been provided between VCB switching behaviour at interruption of 6 and 10kV motors. Voltage escalation has been shown to be the most important process for 6kV motors with respect to switching overvoltages generation. In contrast to 6kV motors three phase virtual current chopping predominates for 10kV motors. It has been deduced that for the majority of the real field applications VCB with the most popular contact material (CuCr base) can create dangerous overvoltages. Switching surge analysis conducted with the aid of Alternative Transients Program (ATP) proved metal oxide surge arrester connected in parallel to VCB contacts to be the most effective way to suppress phase to ground overvoltages. Turn-to-turn overvoltages induced at interruption of medium voltage motors by VCB with described protection have also been studied. These overvoltages have been compared with turn-to-turn overvoltages induced by a breaker that does not interrupt high frequency current at all. Our analysis revealed that maximum turn-to-turn overvoltages induced by VCB with adequate protection do not exceed overvoltages induced by the circuit breaker (ICB) for more then 15% and are lower then similar overvoltages induced by conventional breakers in the same conditions (oil, air, magnetic).

K.K. Zabello, Yu.A. Barinov, A.A. Logatchev, S.M. Shkol'nik

Abstract:

The study dealt with the cathode spot (CS) motion and the burning voltage of a low-current vacuum arc with electrodes of composition CuCr30, subjected to a magnetic field. The arcs with current 25 < I < 35 A burned in longitudinal (normal to the cathode surface) and transversal (tangential) fields as well as in those with the induction vector inclined by angle 5° < < 65° to the cathode surface. Use was made of electrodes with diameter 30 mm and gap 4 mm. The field components, longitudinal Bn and transversal Bt, varied independently in the range from 0 to 0.12 T each. The superposition of the transversal magnetic field on the arc has been found to considerably increase both the constant component and noise level of the voltage. If such arc is superposed also with the longitudinal field, both the constant component and noise level decrease and at Bn ~ Bt the voltage across the arc is weakly dependent of Bt. The velocity of the retrograde (anti-Ampere) CS motion grows approximately in proportion to the growth of the transversal field induction. The proportionality factor is ~200 m/(s×T). The increase in the longitudinal field induction causes a reduction in the magnitude of the velocity vector and its rotation with respect to the anti-Ampere direction through angle , its value being proportional to field inclination angle . The results obtained were compared with the data in references.

S.M. Shkol'nik, V.P. Afanas'ev, Yu.A. Barinov, A.M. Chaly, A.A. Logatchev, S.I. Malakhovsky, I.N. Poluyanova, K.K. Zabello

Abstract:

Earlier we offered technique of high-speed photography of high-current vacuum arc that in combination with the special computer-aided treatment allowed reconstruction of distribution of current density on the cathode. This technique was applied for butt solid contacts with external axial magnetic field (AMF) at relatively low current density j<2 kA/cm². In the present work we have further developed this technique. Advanced technique is applicable for the analysis of current density distribution on the complicated electrodes of commercial vacuum interrupter (VI) carrying current up to I=50 kA at current density up to j~4 kA/cm². The experiments have been carried out for three types of electrode systems generating AMF with different configurations. The obtained results proved previously derived conclusion that current density tends to distribute evenly across that part of the contact surface where AMF induction fits inequity Bz(1)

V.P. Afanas'ev

Abstract:

Experimental dependencies of the mean breakdown field strength, found as the ratio of the breakdown potential difference to the distance between the electrodes, on the distance between the electrodes exhibit a tendency to decrease. The present work deals with the option to explain the dependence by the effect of the spatial self-charge of an electron beam and the emitter geometry.

V.P. Afanas'ev, A.A. Kostin, V.A. Kuptsov

Abstract:

The work examines the problems of calculating the electrostatic field strength near triple junctions, where the boundaries of metal, dielectric and vacuum intersect. It is shown that of much importance is the ratio of opening angles of sectors filled by each medium.

A.M. Chaly

Abstract:

This paper reviews the most important topics related to the control of HCVA with the aid of AMF: the main experimental findings, explanations and theories and the effect of AMF non-uniformity. The state of the art AMF contact systems for commercial vacuum interrupters are also presented.

A.M. Chaly, O.I. Chervinskyi, V.N. Poluyanov

Abstract:

Paper deals with the design and parameters of the new generation of vacuum circuit breakers (VCB) built around novel design of magnetic actuator. Actuator utilizes magnetic system with the serial magnetically hard alloy. The actuator is fixed in closed position by magnetic flux. In the open position it is fixed with the aid of opening spring. Single coil allows providing close and trip actions depending on the direction of the injected current. In each VCB pole separate actuator is installed. These actuators are linked with the synchronizing shaft providing control of auxiliary switches and interlocks. This design allows achieving high mechanical life and maintenance free feature during the entire product lifetime.

Dr. A.M. Chaly, Dr. O.I. Chervinskyi, V.G. Shimchenko, V.V. Zyablov, S.V. Benzoruk

Abstract:

The aim of this article is to offer alternative design of an insulation which allows development of the medium voltage reclosers combined positive effects of manufactured at present time reclosers with SF6 and solid insulation.

A.M.Chaly, A.A.Logatchev, K.K.Zabello, S.M.Shkol’nik

Abstract:

The high-current vacuum arcs (HCVA) with high average current densities in axial magnetic fields (AMF) B <1.2 T were studied. The typical V-shape of Volt-Tesla characteristic (VTC) has been shown to retain in strong AMF and at raising the current density to 3 kA/cm2; the quantitative parameters change, though. It has been confirmed the conclusion of [6] that, in strong AMF, the cathode attachment size for an arc in a quasistationary state is defined by AMF induction and arc length. The quantitative comparison of VTC and voltage of a low-current arc under the action of magnetic field, inclined to the arc axis [16], encounters difficulties arising in describing of HCVA as an aggregate of independent cathode jets at moderate values of AMF induction.

A.M.Chaly, A.A.Logatchev, K.K.Zabello, S.M.Shkol’nik

Abstract:

Experiment dealt with investigating a vacuum arc of length 0 < h <10 mm with current 30 < I < 150 A, which burned at electrodes of CuCr30 composition. The study concerned the dependence of such characteristics as arc burning voltage U and average current passed by a cathode spot Is on the amplitude of the induction vector of external uniform magnetic field B=Bn+Bt and its inclination angle α to the arc axis. The voltage at fixed I and B was found to correlate with the structure of cathode attachment – the number of separately existing spots. Depending on α, variation of the number of spots may bring about both the growth and drop of the voltage by as much as ~Volt. At α → π/2, Is has been found to be strongly dependent on the amplitude of vector B, but at α → 0 the dependence of Is on B practically vanishes. Dependence of average arc voltage U on Bn at fixed current has been studied at different values of Bt. The curves have been shown to distinctly split into three portions: rapid drop, constancy and slow (root-like) growth of the voltage. Transition from one portion to another takes place at certain values of magnetic field inclination angle α1 and α2. Comparison with previously published authors’ results obtained in an arc with copper electrodes [1] has shown that α2 is strongly dependent on the electrode material, whereas α1 practically independent of it. The characteristic values of α have been found to be (weakly) dependent on the arc length and current. Obtained results are of interest not only for the insight into processes in low-current arcs, but also for explanation of regularities that define the behavior of high-current vacuum arcs stabilized by axial magnetic fields.

Jurij V. Khvorost, Andrew S. Baturin, Eugeny P. Sheshin

Abstract:

The peculiarities of field-emission current and NSDD-capability of SSS CuCr 70/30 vacuum gap have been investigated for the commercial vacuum interrupters. It has been found that 1)NSDD is not a result of long-term (more than 100 µs) increase of field-emission current; 2) there is no correlation between average level of emission current and NSDD capability of vacuum gap; 3)there is a strong correlation between NSDD-capability of the contact gap and capability of the gap to generate sharp short-term bumps of the emission current; 4) NSDD and the bumps of the current (often) are followed by the step increase of average emission current, return to the initial value takes the emission current several following periods of applied 50Hz voltage. It has been determined that the duration of the bumps is not more than 10 µs and the bumps are not preceded by field-emission current increase. It has been demonstrated that under the test condition the phenomena of current bumps can not be explained by the mechanism of explosive auto emission. The authors suppose that NSDD and current bumps have the same origin – the bombarding of the contact surface by the particles.

A. M. Chaly, I. N. Poluyanova

Abstract:

An analysis of switching processes at interruption of lightly loaded urban and rural networks with the aid of VCB has been provided. It has been found that typical loading of the distribution feeders result in virtual absence of recovery voltage shift being the main reason for non-sustained disruptive discharges (NSDD). Truly unloaded situation is interruption of section located between neighbouring points of isolation in cable line, but 95% of lengths of these sections are less than 3km that is substantially shorter than ~50km lengths considered by standard. This difference results in different duration of current pulses relevant for VCB closing in real and test cases. Estimation of the probability of contact micro welding has shown that in real case probability of contact welding is much lower which results in lower probability of NSDD. On the basis of the above irrelevancy of the current IEC requirement with regard to general purpose VCB has been stated. Alternative test procedure for special purpose VCB has also been offered.

V.P. Afanas'ev, A.M. Chaly, V.A. Kuptsov, S.M. Shkol'nik

Abstract:

The present work deals with numerical simulation of cathode spot motion in self-consistent magnetic field under the 3D problem statement. Plasma jets are simulated with cylinders of a small fixed diameter, the conductivity of the latter can depend on the magnetic field. Electrodes are simulated in their actual 3D geometry. Magnitude and direction of the velocity of cathode spot motion as dependent on magnetic field components are taken from experimental data on motion of a single spot [1]. When accounting for the dependence of cathode jet conductivity on magnetic field, the conductivity is calculated on the basis of the data on single spot voltage from the same work. In this case, use can also be made of a mechanism of division of spots at the current exceeding some threshold and of their destruction at currents, lower than another threshold. Simulation has shown that the stable configuration at expansion of spot system is a ring in all cases, excepting the one of allowing for mechanisms of threshold division and destruction of spots. Time dependences of average spot system radius (relative to the electrode center) and standard deviation of the radius from the mean were obtained. In case of allowing for the mechanism of threshold division and destruction of spots, a ring is not a stable configuration any more, spots are distributed over an expanding circle in a roughly uniform manner.

V.A. Dmitriev, V.N. Poluyanov , I.N. Poluyanova

Abstract:

The distribution of energy between anode and cathode of high-current drawn vacuum arc has been experimentally evaluated for different CuCr based contact materials. The energy distribution was determined by measurement of the temperature rise with one thermocouple soldered into drilled hole in the holder of the electrode, which was in turns cathode and anode. The measurements were carried out in the commercial vacuum interrupter, 36-55mm in diameter AMF electrodes were made from SSS CuCr 70/30 and LSS CuCr 50/50. The contacts were separated by magnetic actuator with stable and invariable average opening speed 1m/s, maximum contact distance was 7ìì. The arc duration was 8.5-9.5ms in all the tests. The study of material influence on the energy distribution has been done for the typical range of currents for commercial vacuum interrupter 5êÀ – 40êÀ and for the extreme, knowingly overheating regime with current 60êÀ.

Dr. A.M. Chaly, I.N. Poluyanova, V.N. Poluyanov

Abstract:

Maximum interrupting capacity of the butt CuCr 70/30 contacts at external uniform AMF has been experimentally investigated for AMF induction range 0-1.2Ò. It has been found that dependency of maximum interrupting current density versus AMF induction has a tendency to saturate when the latter achieves the level of the first characteristic point B1 on Volt-Tesla characteristic. Radial energy losses have been evaluated on the basis of measured anode mass losses. One-dimensional thermal model has been used for evaluation maximum interrupting current density. At the same time radial energy losses have been taken into consideration. Calculated results demonstrate good agreement with the experimental data if critical temperature equal to ~2000K is considered. This value of critical temperature is supported by several experiments described in literature.

Dr. A. Chaly, K. Gutnik, A. Testoedov, A. Astrakhantsev

Abstract:

The article deals with the problem of coordination of reclosers installed in series in overhead lines. Existing practice is based upon set of rules that require human interference. This may lead to errors and incorrect operation of protection. We have developed a set of algorithms that allow to determine settings of protection elements providing protection against short circuit and sensitive earth faults. Network parameters and grading margins serve as input data for the mentioned algorithms. The algorithms have been tested with the aid of network computer models. The tests proved applicability of the algorithms for field application.

P.A. Baizdrenko, Dr. A.M. Chaly, O.I. Chervinsky, V.N. Gorelov

Abstract:

The paper describes a design concept of the new air-insulated switchboard ETALON. The distinguished feature of this switchboard is an application of the combined switching module, integrating in its design vacuum circuit breaker (VCB) with mono-stable magnetic actuator and series three-positioned selector. The latter provides both disconnecting and earthing operations. Interlocks preventing operation of selector when VCB is closed and operation of VCB when selector is in intermediate position are also integrated in design of the switching module. Despite extreme compactness of the switchboard, advanced bolt- and rivet-free enclosure provides arc-proof behaviour that is proved by relevant tests. As a result ETALON has minimum dimensions among all air-insulated switchboards presented in the market today, i.e. 330mm width for 12kV, 20kA/630A and 470mm for 12kV, 31.5kA/1600A feeders.

Dr. A.M. Chaly, V.V. Vorotnitskiy, S.A. Buzin, S.V. Benzoruk

Abstract:

Recloser philosophy has not been traditionally applied in the former USSR. Structure of networks and relevant problems are not exactly the same as for traditional recloser markets. This paper describes some special cases and relevant solutions provided with the aid of Tavrida Electric reclosers in response to these problems.