Patent ID: 9735713
Date: 2017-08-15
CPC Classifications: F04D,G05B,H02P

Claim:
1. A method for controlling circuitry of a softstarter arrangement to operate an electric motor provided for driving a pump in a pump system, the circuitry electrically connecting the motor to electric mains, the method comprising the steps of: (i) controlling the circuitry of the softstarter arrangement to accelerate the motor up to full speed in a forward direction; (ii) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at full speed in the forward direction for a first period of time; (iii) controlling the circuitry of the softstarter arrangement to accelerate the motor up to a specified speed in a reverse direction; (iv) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at the specified speed in the reverse direction for a second period of time; and (v) repeating the steps (i)-(iv) one or more times, wherein the steps (i)-(v) are configured to cut unwanted solid objects in the pump system by pump blades of the pump and flush away effluent residues; wherein the motor is a three phase motor electrically connected to three phases of the mains and the softstarter arrangement is a two-phase or three-phase softstarter arrangement configured to operate the three phase motor, and wherein the steps (iii) and (iv) are preceded by shifting the electric connections of two of the three phases of the mains to the three phase motor and are followed by shifting back the electric connections of said two of the three phases to the three phase motor, thereby providing the specified speed in the reverse direction to be similar to the full speed in the forward direction, the shifting and shifting back being performed by means of operating two line contactors interconnection between the mains and the circuitry of the softstarter arrangement.