Development of a High-Voltage Bench for Impulse Tests of High-Energy Resistors

Abstract

For testing various devices, for example, high-energy resistors, to withstand the impact of high-voltage impulses, a bench has been developed, which has at its heart a vacuum switch or an electron-beam switch (EBV) that makes it possible to generate triangular or rectangular test impulses. The impulses have an amplitude of up to 30 kV and duration determined by the electrical capacitance and active resistance in the discharge circuit. The capacitor banks used in the bench have a capacitance ranging from 40 to 640 μF and are supposed to operate on a load with resistance ranging from 300 to 5000 Om. The impulse front is determined by the discharge circuit inductance and resistance. The discharge circuit also contains a limiting 5 Om resistor and a 0.1 mH choke. The impulse repetition frequency is limited by the capacity of the DC power supply voltage source and the charger limiting current. The DC power supply voltage source contains a high-voltage three-phase power transformer with natural air cooling and a three-phase rectifier assembled according to the Larionov circuit arrangement. All rectifier diodes are fitted with an individual forced cooling system. The charging device is of an active-resistive type with charge current limitation and contains a few series-connected high-voltage resistors for a maximum voltage of up to 30 kV and power up to 2.5 kW, and with a forced air cooling system. The use of an EВV with the pentode current-voltage characteristic for the maximum continuous current up to 2A, for example, the ELB 2/200 device, as a current-limiting element resistant to a short-circuit fault seems to be the most promising. Its application makes it possible to achieve more reliable operation of the bench charging device owing to the valve ability to limit the current to the valve’s preset anode current value. The maximum value of valve current is determined by the voltage applied to the control electrode. A high-voltage vacuum surge arrester with a KDV-10-20/1000 camera for a switched voltage level of up to 35 kV and peak current of up 51 kA is used as the switching apparatus. For the possibility of safely adjusting the digital measurement instruments, the bench mockup electric circuit to a 1:100 voltage scale has been developed. Experimental investigations of the high-energy resistor with a resistance of about 330 Ω for its ability to withstand an impulse voltage of up to 20 kV applied from a charged 340 μF capacitor were carried out, from which positive results have been obtained. For determining the limit operating modes of the switch, valve, load resistance, repetition frequency, and for optimizing the rated parameters of electrical circuit elements, the bench electric circuit is modeled on a computer using the EWB program.