Abstract: in view of several trips of coal pulverizer motor during the operation of 330MW unit in a power plant, according to the on-site inspection and analysis, it is found that the reason for the trip of coal pulverizer motor is that the wiring in the junction box at the neutral side of the motor is unreasonable, the wiring terminal leads are almost right angle bends, and the wiring terminals are subject to mechanical stress, which is easy to produce stress cracks during the operation, and finally the wiring terminals are broken, and the motor protection action trips, After the transformation of the wiring in the junction box, the mechanical stress of the terminal is eliminated.