 Protection of traction motors from short circuits is accomplished by means of a fast-acting circuit breaker, which disconnects the traction circuit within 2-5 milliseconds if the current exceeds 575±25 amps.In case of a short to ground where the current does not exceed this level, protection is accomplished by a differential relay which compares current at both ends of the circuit and opens the circuit breaker if the difference in current exceeds 40 amps.The traction motors are also protected by a wheelslip relay which trips if the angular velocity of one of the traction motors significantly differs from the others (wheelslip, skidding, stripped gears, etc.)