high current vacuum switch

All-Russian Electrotechnical Institute (VEI), Krasnokazarmennaya 12,111250 Moscow, Russia,
Abstract The series o f new vacuum switching devices for commutation of power energy storages has been developed. To provide reliable and fast commutation of capacitor type energ storages a new type of triggered vacuum swttch (TVS) of sealed off design has been developed - RW-43. This switch provides commutation of curremt pulses with peak value up to 250 kA at working voltage up to 25 kV, with transferred charge in a pulse up to 120 C. Wide range of operating vottage and low swttching voltage level permit to use RW-43 in the crowbar operation mode to apply mono-polar pulses i n the inductance load. Small straggling of triggering delay time provides synchronous parallel switching of TVS on a load, and also series connection of TVS's. Results of TVS tests are presented. The opportunity to increase its limit parameters is discussed. Several types of DC vacuum circuit- breakers were developed to provide commutation of power inductive energy storages with switched currents up to 50 kA with vohge 30-100 kV, PossibUity of series and parallel connections of DC circuit-breakers were investigated.
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in comparison with capacitor ones. For switching of power inductive storages it is necessary to have fast operaD.C. circuit-breakers, capable of multiple operation and a b r e w capacity to 10" W. This can be realized by the use of vacuum D.C. circuit-breakers with forced cunent passing through zero [2]. In this paper there are presented test results of a new power TVS of type RW-43. The TVS provides reliable switchmg of current pulses to 250 kA at operating voltage to 25 kV. There is also presented a description of several types of d.c. vacuum circuit-breakers with brealung currents of 1.5 kA - 50 kA at voltages 30 kV - 200 kV. Possibilities of series and parallel connection of vacuum switchmg devices are considered.
Development of pulsed power technologies makes great demands to switchmg devices, whch are one of the most important parts of any pulsed power supply. A switchmg device has to pass lugh currents and w i t h s t a n d s high voltages and w i t h t l x it should be reliable, durable and provide ?agh technology efficiency. Requirements to s w i t c h devices depend also on the type of energy storage. In supplies with a capacitor type storage a switchmg device should switch-on the capacitor bank to the load quickly and reliably and provide multiple passing currents up to hundreds of kiloamperes with a duration from several microseconds to several milliseconds. It is very appropriate to use for these purposes triggered vacuum switches WS) of sealed-off design [ 1J which are characterized by wide operating voltage and current range: U = 1 kV - 50 kV, I = 0,Ol kA - 200 kA. Inductive energy storages allow one to increase the level of stored energy, and they possess hgher specific characteristics
Index Terms - Triggered vacuum switch, DC vacuum circuit-breakers. vacuum arc.
I. INTRODUCTION
Sealed-off TVS are three electrode vacuum sealed devices without filament heating and with residual gas pressure not more than 10" Pa [3]. TVS triggering is realized with putting the triggering pulse on the control electrode. The triggering pulse causes breakdown of a triggering gap and generation of spark discharge. As a result, vacuum arc arises in the vacuum gap between main electrodes. Vacuum arc exists and self-sustains to the end of power current pulse or to the current crossing zero. TVS making time, as a rule, does not exceed 1 p s - 2 p s and does not depend practically on operabng voltage at main electrodes. The choice of electrode system and the design of a TVS depend on its application. TVSs in which the electrode system is an array of rods of altemate polanty [4] have the largest switchmg capacity (for switching current and charge). Using such an electrode system, VEI developed a switch of type RW-40 with operathg currents up to 100 kA at voltage to 20 kV [5]. Many years senice experience of RW-40 at currents of more than 100 kA showed that the most critical component of the switch is the m e r unit. The other important problem is the improvement of erosion strength and electric strength of the main electrode system. Investigations of Merent modes of high-current vacuum arc initiation were canied out to increase a service life of a trigger unit [ti]. Investigation results showed that RW-40 service Me can be prolonged when it is used in the anode mode of operation (the control electrode is placed on the switch anode flange). However, for realization of such operating mode considerable increase of tngger pulse energy is required. It was shown fiom the other side that there i s 3 lot