| 摘要 |
PURPOSE:To contrive prevention of burning of an electromagnet by a method wherein a bidirectional constant voltage element such as a varistor and the like is used as a discharge element, thereby enabling to prevent generation of a branching-off to the discharge element even when said element is being excited or demagnetized. CONSTITUTION:A bidirectional constant voltage element 8 such as a varistor and the like is used as a discharge element instead of a resistor 1 and a diode 2. The operating voltage of said constant voltage element 8 is selected in such a manner that it will be a little higher than the exciting or demagnetizing voltage of the electromagnet. As a result, no branching-off is generated on the discharge element 8 when it is excited or demagnetized, and no heat is generated. When an OFF position is given to a superconductive switch 4 and the electromagnet is quenched, a voltage is generated at both ends of the electromagnet, the discharge element is turned to a constant-voltage resistor, and the magnetic energy of the electromagnet is absorbed by said constant-voltage resistor. An electric discharge is generated in the state of constant voltage, the current on the electromagnet is reduced rectilinearly as time elapses. |
