High Frequency Current Interruption Research Articles

真空遮断器における高周波電流遮断後の絶縁回復特性

真空遮断器における高周波電流遮断後の絶縁回復特性

Characteristics of Triggered Vacuum Switch With Single Axial Magnetic Electrode for High-Frequency Current Interruption

For the purpose of repetitive pulsed power applications, specially designed triggered vacuum switches (TVSs) were tested under different high-frequency currents in this contribution. Two TVSs named as TVS-1 and TVS-2, respectively, were designed to investigate the high-frequency current interrupting characteristics with or without an axial magnetic field (AMF) aid. The TVS with AMF at the cup-shaped anode can generate a magnetic field parallel to the arc column by the flowing current itself. TVSs show promise for use in high-current and high-frequency conversion and switching circuits. The $V/I$ characteristic results show that the arc voltage increases with increasing the arc current. The maximum interrupting main current has a sharp decreasing trend with increasing the current frequency from zero to 1 kHz, whereas the curves tend to be flat after 1 kHz. The AMF in the anode gives great aid to decrease the arc voltage and increase the high-frequency current interrupting capacity of the TVS.

Influence of electrode surface microstructures on the state of shortvacuum gaps after interruption of high-frequency currents

In this paper the influences of electrode surface microstructures onthe electrical field near the new cathode surface and on the distribution ofion density and velocity in the space-charge region after interruption ofhigh-frequency currents in short vacuum gaps have been studied. To investigatethese effects, the equations of conservation of mass and momentum are solvedtwo dimensionally in the space-charge region. The results indicate aconsiderable increase in ion density at the points with high electricalfields, which results in an enhancement of the electrical field at thesepoints compared with one-dimensional calculations. Considering the calculatedelectrical field near the cathode surface and the power density deposited intothe cathode surface by ions, the initiation of a breakdown during the post arcperiod under the mechanism of explosive electron emission may be possible.

真空開閉器における高周波消弧の数値模擬

真空開閉器における高周波消弧の数値模擬

Low Surge Vacuum Circuit Breakers

Low surge vacuum circuit breakers were developed which used a new electrode material cobalt-silver-selenium alloy. Their chopping current level was below 1.0 A and their high frequency current interruption ability was about 24 Aús. These levels were much lower than those of conventional electrode materials and did not change after load current interruption lifetime and short circuit current interruption tests. From switching tests with motors and no-load transformers, safe operation of these vacuum circuit breakers, without any surge absorber, was confirmed ; the surge level caused by current chopping and the multiple reignition surge level caused by high frequency current interruption were far below the apparatus insulation levels. Furthermore, the new material showed good interruption ability.