QUENCH PROTECTION OF SUPERCONDUCTING MAGNET USING ZNO ARRESTER

A new quench protection method for superconducting magnets is presented. The method utilizes ZnO arresters as external dump resistors instead of conventional resistors. The ZnO arresters, which are widely used in power systems to limit overvoltages, can be used as the energy absorbing element with a constant discharge voltage. By introducing the ZnO arresters, both the discharge time and the heat dissipation in the superconducting magnet are reduced. The authors carried out some experiments using small experimental magnets. The results show that the ZnO arrester works as a dump resistor for a superconducting magnet and it is confirmed that the heat dissipation in the superconducting magnet with ZnO arresters is about one-third smaller than that with conventional dump resistors for the same maximum transient voltage.