Method of operating variable-speed submersible pump unit

A method of operating a variable-speed pump driven by a motor capable of developing high torque at low speeds, comprising the steps of:

• a. running the pump at a first selected speed;
• b. determining whether the pump is clogged by assessing the torque being generated by the motor;
• c. 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;
• d. determining whether the pump is still clogged by assessing the torque being generated by the motor;
• e. 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;
• f. at any point when it is determined that the pump is no longer clogged, resuming pumping at said first selected speed;
• g. when the selected speed is reduced to a minimum speed and it is determined that the pump is still clogged, the steps of:
• g1. running the pump backwards;
• and
• g2. repeating steps a. through f.;
• and
• h. running the pump forwards at maximum speed for a predetermined period of time.

A variable speed pump controller for a pump submersed in a vessel, said controller comprising a computer program for controlling the pump, said program comprising machine readable coded instructions for performing the following steps:

• 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 clogged by assessing the torque;
• if the torque exceeds a maximum for the newly selected speed, repeating the steps of reducing the speed and permitting the torque to rise;
• and if at any point it is determined that the pump is no longer clogged, resuming said first selected speed.

A variable speed pump controller for a pump submersed in a vessel, said controller comprising a computer program for controlling the pump, said program comprising machine readable coded instructions for performing the following steps:

• 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 clogged by assessing the torque;
• if the torque exceeds a maximum for the newly selected speed, repeating the steps of reducing the speed and permitting the torque to rise;
• if at any point it is determined that the pump is no longer clogged, resuming said first selected speed;
• and
• if the selected speed is reduced to a minimum speed and it is determined that the pump is still clogged:
• running the pump backwards, and
• repeating the first through sixth steps recited above;
• and
• running the pump backwards a second time, forwards a third time, and backwards a third time.

A computer program for controlling a variable speed submersible pump, said program comprising coded instructions for performing the following control steps:

• 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 unless and until it exceeds a maximum for the newly selected speed;
• repeating the steps of reducing the speed and permitting the torque to rise;
• and if at any point it is determined that the pump is no longer clogged, resuming said first selected speed.

A computer program for controlling a variable speed submersible pump, said program comprising coded instructions for performing the following control steps:

• a. running the pump at a first selected speed;
• b. determining whether the pump is clogged by assessing the torque being generated by the motor;
• c. 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;
• d. determining whether the pump is still clogged by assessing the torque unless and until it exceeds a maximum for the newly selected speed;
• e. repeating the steps of reducing the speed and permitting the torque to rise;
• f. if at any point it is determined that the pump is no longer clogged, resuming said first selected speed;
• g. when the selected speed is reduced to a minimum speed and it is determined that the pump is still clogged:
• g1. running the pump backwards;
• and
• g2. repeating steps a. through f.;
• and
• h. running the pump forwards at maximum speed for a predetermined period of time.

A method of operating a variable-speed pump driven by a motor capable of developing high torque at low speeds, comprising the steps of:

• determining whether the tank is sufficiently full for emptying to be appropriate;
• when emptying the tank is not appropriate, determining whether a predetermined period has elapsed since the pump was last run;
• running the pump backwards to agitate the tank when the predetermined period has elapsed;
• when emptying the tank is appropriate, running the pump backwards to agitate the tank;
• after agitating the tank, running the pump forwards at a selected speed to remove contents from the tank;
• 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;
• assessing the torque;
• when the torque exceeds said 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.

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 pumping fluid at a predetermined rate;
• if not, determining whether the pump is operating at a maximum speed;
• if not, incrementing the speed of the pump;
• repeating the determining and incrementing steps until either the speed of the pump reaches said maximum speed or the rate of pumping reaches said predetermined rate;
• 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;
• repeating the steps of assessing the torque and reducing the speed;
• and
• at any point when it is determined that the pump is no longer clogged, resuming pumping at said first selected speed.