Method and apparatus for maximizing utilization of an electric motor under load
AssigneeDresser Industries, Inc.
InventorFredrick R. Johanson
Life of this patent
Estimating the term…
Abstract
The present invention relates to an electronic device that is used to calculate the actual torque being produced by an electric motor at any instant in time and comparing this value of torque ratiometrically either with the maximum (peak) torque that the motor could produce under the line voltage available at that instant or with rated motor torque, thus giving an indication of whether the motor is approaching stall or is under utilized or over utilized.
Claims21
A method of adjusting the load on an electric motor having a known speed/torque relationship to maximize its utilization comprising the steps of:
- a. generating a first signal representing the actual instantaneous speed of said motor;
- b. generating a signal representing the actual instantaneous motor line voltage;
- c. comparing said first generated speed signal to data representing a known speed/torque relationship of said motor at said instantaneous voltage to generate a second signal representative of instantaneous actual torque, a third signal representative of rated torque and a fourth signal representative of peak torque at said instantaneous line voltage;
- d. comparing said third or fourth signals representing, respectively, the rated or peak torques of said motor at said instantaneous line voltage with said second signal representing actual torque;
- and
- e. varying said load on said motor in accordance with said actual torque comparison to obtain said maximum utilization of said motor.
Apparatus for adjusting the load on an electric motor having a known speed/torque relationship to maximize its utilization comprising:
- a. means for generating a first signal representing the instantaneous speed of said motor;
- b. means for generating a signal representing the actual instantaneous motor line voltage;
- c. means for comparing said first generated speed signal to data representing a known speed/torque relationship of said motor at said instantaneous voltage to generate a second signal representative of instantaneous actual torque, a third signal representative of rated torque, and a fourth signal representative of peak torque at said instantaneous line voltage;
- d. means for comparing said third or fourth signals represnting, respectively, the rated or peak torques of said motor at said instantaneous line voltage with said second signal representing actual torque for generating a signal representing the difference between said rated and peak torque and said actual torque;
- and
- e. means coupled to said torque comparing means for varying said load on said motor in accordance with said actual torque comparison to obtain said maximum utilization of said motor.
Apparatus as in claim 11 or 16 wherein the means for generating said second signal representing actual torque of said motor comprises:
- a. means for storing data signals representing the family of speed/torque characteristic curves at, over, and under rated line voltage;
- b. means for comparing said signals representing said actual instantaneous speed and voltage with said signals representing said stored family of speed/torque/voltage curves;
- and
- c. means for generating said second signal representing actual torque when a comparison is found between said actual instantaneous speed and voltage and said stored speed and voltage.
Apparatus for determining the load on an electric motor having a known speed/torque relationship comprising:
- a. means for generating a first signal representing the instantaneous speed of said motor;
- b. means for generating a signal representing the actual instantaneous motor line voltage;
- c. means for comparing said first generated speed signal to data representing a known speed/torque relationship of said motor at said instantaneous line voltage to generate a second signal representative of instantaneous actual torque of said motor;
- and
- d. means coupled to said comparing means for visually displaying said second signal representing instantaneous actual torque of said motor.
Apparatus for determining the load on an electric motor having a known speed/torque relationship comprising:
- a. means for generating a first signal representing the instantaneous speed of said motor;
- b. means for generating a signal representing the instantaneous motor line voltage;
- and
- c. means for comparing said first generated speed signal to data representing a known speed/torque relationship of said motor at said instantaneous line voltage to generate a second signal representative of instantaneous actual torque of said motor.
Dependencies are inferred from the claim text.