This device is composed of automatic air switch, high-power thyristor, vacuum contactor, central controller, soft-start controller, capacitor, varistor and so on. The device is mainly for the current pump starter phase sequence protection function developed defects, because the pump unit does not allow reversal, once the unit reversal, one is caused by this well without liquid volume affect the crude oil output; the second is caused by the crew Cooling worse, the temperature increases the respiration of the protector increases, the loss of insulating oil increases, the internal rubber parts become brittle and hard, losing the protection function, so that the underground motor burned quickly. In addition, the starting device used in the current electric pump well has no energy saving and power factor compensation function, resulting in the waste of electric energy and energy, and can not increase the power of the motor to reduce the power factor of the motor, and the starting device now used has no voltage balance Protective function. Once the voltage is too high or too low to make the underground motor can not run in balance, resulting in frequent overloading or downhole units downtime, the motor will burn in severe cases. The development of this device successfully solved the above problems. Solve all the impact of electrical equipment and pump unit start causing a larger starting current on the supply voltage and the line power consumption increases and the impact of electrical equipment, more importantly, to solve the pump unit reversal problem. In addition, the unit to solve the problem of power factor compensation and improve the power factor, energy saving effect of more than 25%, the effect is obvious. This device has a varistor, which can effectively protect the motor from overvoltage, absorb the back EMF when the motor is stopped, and absorb the residual magnetic energy in the motor. The device is based on advanced 16-bit microcontroller and COM integrated circuit as the central controller, control of high-power thyristor components, with torque control of the soft start, current limit start, full voltage start, dual ramp start, soft stop function , And has over-current protection, overload protection, underload protection, single-phase protection, undervoltage protection, overvoltage protection, phase sequence protection, delay automatic start and other functions. Parameters can be set according to user needs, can be widely used in a variety of electric drive oil fields, for example, can be used in oil pumping stations, pumping units, submersible pumps and other electrical equipment used to drag.