Design of Protection Method for ELCID Test

In this paper, a protection scheme is proposed for the rotor shaft to ground short circuit fault in the electromagnetic core imperfection detector (ELCID) test without removing the rotor. When the rotor shaft is accidentally grounded, hundreds of ampere short-circuit current may be generated to damage the equipment. A low-turn transformer model is established for the test device. The parameters are obtained by the open / short-circuit test, and the influence of the excitation branch under low winding turns is considered. The accuracy of the parameter acquisition method is verified by MATLAB Simulink simulation. Based on ANSYS finite element simulation analysis of fault current characteristics, it is proposed to install a current limiting reactor at the entrance of the excitation cable to suppress the steady-state short-circuit current, and use a solid-state circuit breaker to achieve fast-break protection. Threshold and curvature judgment are used to ensure fast fault identification and effectively solve the problem of traditional protection delay.