The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 29, 2003
Filed:
Oct. 29, 2001
Noriyuki Takada, Fukuoka, JP;
Takayuki Yamakawa, Fukuoka, JP;
Hidetoshi Ryu, Fukuoka, JP;
Tetsuo Kawano, Fukuoka, JP;
Koji Kawamoto, Fukuoka, JP;
Toshio Miyano, Fukuoka, JP;
Richard L. Pratt, Ohio, OH (US);
Brian Mackinnon, Alberta, CA;
Kabushiki Kaisha Yaskawa Denki, Fukuoka, JP;
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.