US 6,599,095 B1 · Pump-off control method of pump jack

Abstract

A pump off control method comprises detecting the speed of the induction motor and an instantaneous value of secondary current of the induction motor. Down stroke time in every cycle of the pump jack is detected. An average value of instantaneous values of the secondary current of the induction motor in the down stroke time in said every cycle is calculated. An average value reference of the secondary current of the induction motor to be compared with calculated average value of the instantaneous values of the secondary current of the induction motor is set. The calculated average value of the instantaneous values of the secondary current is compared with the average value reference after the down stroke end in each cycle. An occurence of pump off is detected if the calculated average value of the instantaneous values is greater than the average value reference.

Claims9

Dependent claims

A system for pump off control of a pump jack drive system of induction motor drive comprising:

means for detecting speed of the induction motor and an instantaneous value of secondary current of the induction motor;
means for detecting down stroke time in every cycle of the pump jack;
means for detecting each maximum value of the secondary current instantaneous values in each down stroke time of the secondary current;
means for detecting and storing a time value from each down stroke reference point to said each maximum value of the secondary current instantaneous values;
and
means for setting a reference time value to be compared with the detected and stored time value,
wherein the system is capable of comparing the detected and stored time value with the reference time value after the down stroke end every cycle and the system is further capable of detecting an occurrence of a pump off condition as a case where the time at which the instantaneous value of the secondary current reaches the maximum value lags behind the setup reference value.

4 more elements

A pump off control method of a pump jack drive system adapted to control speed of an induction motor for driving a pump jack, said pump off control method comprising the steps of:

a) detecting the speed of the induction motor and an instantaneous value of secondary current of the induction motor;
b) detecting down stroke time in every cycle of the pump jack;
c) calculating an average value of instantaneous values of the secondary current of the induction motor in the down stroke time in said every cycle;
d) setting an average value reference of the secondary current of the induction motor to be compared with calculated average value of the instantaneous values of the secondary current of the induction motor;
e) comparing the calculated average value of the instantaneous values of the secondary current with the average value reference after the down stroke end in each cycle, and
f) detecting occurrence of pump off if the calculated average value of the instantaneous values is greater than the average value reference.

3 more elements

Dependencies are inferred from the claim text.

Pump-off control method of pump jack

Life of this patent

Pump-off control method of pump jack

Life of this patent

Abstract

Claims9