DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.
ఏసీ వ్యవస్థ ఇండక్టివ్ రియాక్టన్స్ సమస్యను పరిష్కరించడానికి రైల్వేలు ఎలా ప్రయత్నిస్తాయి?
low AC frequencies