Study on Protection Technology of Overload and Open-phase of Minitype Flameproof Motor

The existing defect of overload, open phase protection of minitype flameproof motor used in coal mine was analysed and its improved protection scheme was presented. The iterative algorithm which according with motor’s heat characteristic was used to protect dynamic overload, fault signal of open phrase was gained by adopting AC sampling and sequence filtration algorithm. Finally, the above schemes were analysed and calculated in detail and their realizing methods were given.