Study into overcurrent protection technology for mine asynchronous motor

摘要

In the running of mine motor, it is extremely vulnerable to overcurrent faults such as short-phase failure or short circuit, so the study in overcurrent protection for asynchronous motor is of great significance. The characteristics of overcurrent failure for mine asynchronous motor are analyzed, a mathematical model of overcurrent fault is established and the overcurrent protection principle is analyzed in this paper. Due to the malfunction defect of traditional symmetrical short-circuit protection in the starting of large motor, a new protection scheme is proposed, which is to adopt the phase-sensitive protection based on power factor detection and short-circuit fault detection scheme based on wavelet transform Mallat algorithm. Meanwhile, a method of asymmetrical fault protection based on negative-sequence current detection is proposed in the paper. In addition, overcurrent protection technology is applied to the overcurrent protection of mine squirrel cage asynchronous motor, of which the effectiveness and the practicality have been verified.