FIELD: converter engineering; transportation facilities. SUBSTANCE: device has capacitor, thyristor, and diode differentially interconnected in parallel, motor emergency current sensor, voltage divider whose output is connected to capacitor, current pulse shaper whose output is connected to thyristor gate junction. It is also provided with additional thyristor connected to main field coils and second current pulse shaper whose output is connected to gate junction of additional thyristor. EFFECT: provision for protecting tractive motors of electrified rolling stock by fast suppression of magnetic field in air gap with main field coils powered from thyristor converter. 2 cl, 4 wdge
