Dynamic braking cabinet refers to the auxiliary equipment used to rapidly reduce motor running at a high speed to hand wheel control slow speed. Dynamic braking will automatically input and release so long as driller release foot switch about 3s. More than 20s can be saved if a drill stem is elevated. Excitation power, braking contactor and voltage-reducing relay, etc. are installed in the cabinet. Braking resistance: Kinetic energy of motor running at a high speed is converted into heat energy release so as to reach the purpose of rapidly reducing to DC motor’s rotational velocity.