Because the working site of deep well pump is in downhole surroundings, the operator can not judge the turning direction of the pump. However, the unique phase sequence protection function of SSR can effectively prevent the inversion of deep well pumps and solve the problems of the field workers. Generally, deep well submersible pumps have large lift, and water hammer phenomenon is obvious in non-soft shutdown, which seriously damages pump base, wellbore, riser and impeller. Pump failure is obviously reduced after the application of SSR soft start for this kind of load. Some submersible pumps (such as high and low pressure water supply mode) start and stop frequently, so its highly recommended to use SSR soft start to avoid arc, adhesion, burnout and other faults caused by the use of contactors to directly start motor, and also saves energy.