Patent ID: 6481973
Filing Date: 2002-11-19
Classification: F04D

Abstract:
A method of operating a variable-speed pump driven by a motor capable of developing high torque at low speeds, comprising the steps of:running the pump at a first selected speed; determining whether the pump is clogged by assessing the torque being generated by the motor; when the torque being developed by the motor exceeds a maximum for the selected speed, reducing the selected speed of the pump and thereby increasing the maximum acceptable torque for the motor; determining whether the pump is still clogged by assessing the torque being generated by the motor; when the torque exceeds said increased maximum acceptable torque for the newly selected speed, repeating the steps of reducing the speed and assessing the torque; and at any point when it is determined that the pump is no longer clogged, resuming pumping at said first selected speed.