A novel simple technology for power switching in HVDC system

In this paper, a novel simple power switching method for dc switching devices is proposed to apply to HVDC system of more than 380 V DC. The method extends and extinguishes an arc between electrical contacts when opening power circuit. In addition, the power circuit can be disconnected even if the current direction reverses. The method is composed simply by using a unique combination of a small magnet, a rod-like iron core and an insulator. Moreover, it is able to prevent thermal demagnetization of the magnet, and besides, the method does not require a strong force and large magnet by using the core as a magnetic medium. In validation experiment, it was confirmed that the control to make the arc collide with an insulator in the method enhances the current interruption performance more than the case using an extinguishing gas. Furthermore, it was demonstrated to disconnect a power circuit of 800 V 20 A DC by using an actual device.