Experimental results with SL/NL breakers

The switching-off effect of a superconductive/normal conductive (SC/NC)-breaker (cryotron) is based on the increase of the resistance from 0 to a determined value, if the transition from the superconductive to the normal conductive state is triggered. The fast commutation of a current from one branch of a network to another can be started by the switching-off effect of a SC/NC-breaker. Results of several tests with SC/NC-breakers suitable for high currents up to 800 A are reported. The relation between the switching time or the commutation time and the rise time of the trigger current pulse, the energy of the pulse, the direct current of the breaker before triggering and a few other electrical parameters are determined experimentally. The demonstration that during commutation an intrusion of electrical energy from the trigger-pulse-circuit into the main circuit never can be compensated completely is an important result of the measurements.