Speed control for a pumping system

• US 20030138327A1
• Filed: 01/18/2002
• Published: 07/24/2003
• Est. Priority Date: 01/18/2002
• Status: Abandoned Application

• Current Assignee: F E. Meyers
• Original Assignee: F E. Meyers
• Inventors: Jones, Robert, Chandler, William, Gibson, Julie
• Application Number:
  US10/051,403
• Publication Number:
  US 20030138327A1
• Time in Patent Office: Days
• US Class Current: 417/42
• CPC Class Codes: F04B 49/20 by changing the driving speed
• CPC Class Codes: F04D 15/0066 by changing the speed, e.g. of the driving engine

Abstract

A wastewater pumping system includes a centrifugal pump operatively connected to an electric motor via a coupling. The speed of the electric motor is automatically varied responsive to the head or load realized by the pump of the system as it varies with the composition of the slurry mixture. A variable frequency drive is operatively connected to the motor and the electrical power supply that affects a shift or change in electrical frequency delivered to the electrical motor so that the speed of the motor and consequently the pump is varied. This allows the electrical power deliver to the system to remain substantially unchanged for varying loads realized by the pump.

Claims

1. A fluid pumping system, comprising:

a pump operable to pump associated fluid;

a motor operatively coupled to drive the pump; and

,

a controlling device electrically communicated between an associated electrical power source and the motor, wherein the controlling device is operable to change the speed of the motor responsive to a change in the load of the pump, while maintaining substantially constant voltage and constant current.

2. The pumping system of claim 1, wherein the speed of the motor is changed by adjusting the frequency of electrical power being supplied to the motor.

3. The pumping system of claim 1, wherein the controlling device includes:

variable frequency controlling means operably communicated to deliver variable frequency electrical power to the motor.

4. The pumping system of claim 3, further comprising:

a sensor operatively communicated to the variable frequency controlling means, and,

wherein the variable frequency controlling means delivers variable frequency electrical power to the motor responsive to the sensor output.

5. The pumping system of claim 4, wherein the sensor is a load current sensor for use in feeding back load current being drawn by the pumping system.

6. The pumping system of claim 1, further comprising:

a reference signal storing means for use in storing a plurality of reference signals, the reference signal storing means being operatively communicated with the controlling device; and

,

wherein the magnitude of constant current is maintained relative to one of the plurality of reference signals stored in the reference signal storing means.

7. The pumping system of claim 6, further comprising:

selectively adjustable switching means for use in selecting said one of the plurality of reference signals stored in the reference signal storing means, the selectively adjustable switching means being operatively communicated with the reference signal storing means.

8. A wastewater pumping system, comprising:

a centrifugal pump operable to pump an associated wastewater slurry;

an AC motor operatively coupled to drive the pump; and

,

a control panel operatively connected drive to the AC motor, the control panel being operable to receive associated electrical input power, the control panel including;

a load current sensor,

a variable frequency drive operatively communicated to the AC motor and the load current sensor, and,

wherein the variable frequency drive is operable to change the speed of the motor responsive to the output of the sensor, while maintaining substantially constant voltage and constant current.

9. The pumping system of claim 8, further comprising:

a reference signal storing means for use in storing a plurality of reference signals, the reference signal storing means being operatively communicated with the variable frequency drive; and

,

wherein the magnitude of constant current is maintained relative to one of the plurality of reference signals stored in the reference signal storing means.

10. The pumping system of claim 9, further comprising:

selectively adjustable switching means for use in selecting said one of the plurality of reference signals stored in the reference signal storing means, the selectively adjustable switching means being operatively communicated with the reference signal storing means.

11. A method for controlling a pumping system, the steps comprising:

providing a centrifugal pump operable to pump an associated slurry,

an AC motor operatively coupled to drive the pump,

a load current sensor; and

,

variable frequency controlling means operatively communicated to the AC motor and the load current sensor,

operating the pumping system;

sensing a change in the load current of the motor;

automatically varying the frequency of the electrical power responsive to the change in the load of the pump while maintaining substantially constant current supplied to the AC motor.

12. A method for controlling a wastewater pumping system, the steps comprising:

providing a centrifugal pump operable to pump an associated wastewater slurry,

an AC Induction motor operatively coupled to drive the pump,

a load current sensor,

a variable frequency drive operatively communicated to the AC motor and the load current sensor,

a reference signal storing means for use in storing a plurality of reference signals, the reference signal storing means being operatively communicated with the variable frequency drive, and,

selectively adjustable switching means for use in selecting one of said plurality of reference signals stored in the reference signal storing means, the selectively adjustable switching means being operatively communicated with the reference signal storing means;

selecting one of a plurality of reference signals;

operating the pumping system;

sensing a change in the load current of the motor;

automatically varying the frequency of the electrical power responsive to the change in the load of the pump, while maintaining substantially constant current supplied to the AC Induction motor relative to said one of a plurality of reference signals.