Capacitive Current Interruption With Air-Break High Voltage Disconnectors

Abstract

Abstract-Capacitive current interruption with air-break disconnectors in a high-voltage network is an interactive event between the circuit and arc with a variety of interruptions and reignitions. In this contribution, first, a theoretical analysis related to this interaction is presented. The effect of capacitances at the source side ( ) and load side ( ) is investigated. Three distinct frequencies are identified as contributing to the voltage and current events in the circuit. Besides the power frequency quantities, a medium frequency transient arises related to the excursion of voltage across capacitances to the applied voltage, and a high-frequency transient arises due to charge redistribution between load-and source-side capacitance at reignition. Second, experimental results from an interruption measurement are studied in detail. Typical waveshapes of voltages across the capacitances, disconnector, and currents through the disconnector show that the transients during interrupted are in agreement with the theoretical analysis. Reignition voltage of the air gap and energy input to the arc on reignition are also studied. It is concluded that besides a higher interruption current and a higher power supply level, a lower ratio leads to more severe interruption and longer arc duration. Finally, the actual status of IEC recommendations on testing, that has taken into account this arc-circuit interaction, is summarized.

Current interruption phenomena in HV disconnectors with high-speed opening auxiliary contacts

“…The range of the highest re-ignition voltages is from 200kV-289kV (1.4-2.0 p.u), which is close to the maximum TRV. Also high reignition currents with values up to 531A in these tests are observed at high frequency when the capacitor banks at both sides equalize upon re-ignition [11]. After the re-ignition at t 3 , the arc extincts completely at the next current zero crossing and the interruption is successful.…”

“…The arc reignites again at this point. Due to the source and load side capacitors' charge equalization [11], a high-frequency current of 220A is observed (Fig. 4d), but overvoltages across load-and source side capacitors are not observed.…”

“…12 shows the arcing time spreads between 45ms and 75ms. It is much shorter compared to the arcing time from an interruption using a disconnector without whip, where the arcing time normally lasts a few hundred milliseconds, and even can be up to several seconds [4], [11]. According to the tests, the arcing time does not appear to have a clear relationship with the interrupted current, at least for values up to 9A.…”

Experiments on Capacitive Current Interruption with Air-Break High Voltage Disconnectors

“…Most of these conclusions can be explained from theoretical point of view [17], showing that with smaller C s /C l , transients in current and voltage are larger.…”

“…As the HF and MF oscillations are damped out, the power frequency (PF) remains. A detailed theoretical analysis is given elsewhere [17].…”