Effect of Faulty Solenoid Starter on the DC Series Motor Performance in Railway Industry

Cranking railway engines in high currents could lead to a series of undesirable effects on the starter motor such as melting copper contacts and disk inside the solenoid. This paper investigates the impact of a defective solenoid on the performance of a DC series motor starter. First, the effect of the starting system on the solenoid parts (i.e., the melting phenomenon in copper contacts and disk inside the solenoid) is described via Finite Element (FE). Next, the circuit model of the DC series motor with the solenoid starter is established to obtain the motor performance. Results reveal that subjecting the contactor disk to a current of 1250 A for 30 ms would melt the disk and cause surface defects. The faulty/melted disk subsequently raises the circuit resistance to 2.9 m ohms. The presented solution can detect the faults effect within $0.05~s$ time frame. Simulation results are supported via a series of experimental measurements and detailed theoretical discussion.