A New Type Rotating Arc Gap Switch and Its Arc Velocity Characteristics

A rotating arc gap (RAG) switch controlled by an axial magnetic field is designed and built to meet the requirements of high voltage, high current, large charge transfers, slight electrode erosion, and long lifetime. The electrodes are in a coaxial cylinder configuration. The shape of the electrodes is optimized to make the electric field well distributed. Therefore, the arc initiates randomly on the electrode. After the gap is triggered, a self-generated magnetic field exists while the arc current flows through the coils which are placed both at the top and bottom of the switch and in series with the inner electrode. The resultant magnetic field is mainly in the axial direction and forms a mirror machinelike configuration. This makes the rotating arc move to the middle of the electrode, no matter where it ignites, and avoid damage to the insulator of the switch body. B-dot probes are used to measure the arc velocity. The experimental current is a trapezoidlike waveform and is generated by a time-sequence discharge power supply. The current value is in the range of 17-72 kA, and the magnetic induction values are in the range of 0.104-0.628 T. The arc velocity in different magnetic field strength is obtained by changing the coil number. The results are compared with other RAG switches. The relationship between arc velocity and the current and magnetic field is obtained from the experimental data. The result shows that the arc velocity in this switch is primarily determined by the magnetic field. This research supplements the arc velocity characteristics of a self-induced driven arc in the high-current range.