JPS5477095A - Superconductive coil device - Google Patents

Abstract

PURPOSE:To prevent accident owing to too early procedure operation before it occurs by detcting the OFF of a heater source and temporarily stopping the change in the output current of an exciting power source with the detection output thereof at the time of controlling a heat type permament current switch. CONSTITUTION:A superconductive coil 1 is contained in cryogenic vessel 2 and heater current Ih is supplied from a power source 5 to the controlling heater coil 3a of a heat type permanent current 3. Exciting current is supplied from a power source 4 to the coil 1. Separately, contacts AHa, AHb which cooperate to the ON or OFF of the current Ih are inserted in series to the output current control circuit of the power source 4 and the contacts AHb are series connected to a timer TR which is energized by the voltage between buses P, N. The delay time T of TR is set at the time until the coil 3a sufficiently cools and the switch 3 goes ON after the current Ih has been cut off. The normally closed contacts TRa of TR are then parallel connected to the contact AHa. In this way, quenching of the coil 1 owing too early operation is prevented.