Cycloconverter behavior for a grinding mill drive under firing pulses fault conditions

Malfunction of the electronic control system or defects in the electronic equipment among other causes can lead to different kind of faults in high-power cycloconverter-fed mill drives. This paper presents a study of the behavior of a cycloconverter for a grinding mill drive under firing pulses fault conditions. For this purpose, a controlled three-phase, six-pulse cycloconverter system, operating from a 50 Hz input, was simulated. Several firing pulses fault conditions are considered: synchronism failure, firing pulses failure and loss of blocking capability. Simulation and experimental results support the understanding of the different failures modes of the cycloconverter and the trouble-shooting in industrial equipment. The application of these modern tools, simulations and real-time controlled cycloconverter model, allows the improvement of reliability and availability of industrial grinding circuits with better procedures and instrumentation system for the real time surveillance, for trouble-shooting, fault detection and recognition of abnormal operating conditions.