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:
Mar. 18, 2003
Filed:
Jan. 12, 2001
Steven A. Johnson, Hartland, WI (US);
Kip M. Larson, Rapid City, SD (US);
Dee R. Walker, Rapid City, SD (US);
Sta-Rite Industries, Inc., Delavan, WI (US);
Abstract
A method and apparatus for controlling an electric motor pump. The method includes the acts of providing an AC power signal having a positive half cycle and a negative half cycle, measuring the voltage of the AC power signal and generating a first two-state output signal that is in a logic high state when the measured voltage is on the positive half cycle and that is in a logic low state when the measured voltage is on the negative half cycle, and measuring the current of the AC power signal and generating a second two-state output signal that is in logic high state when the measured current is on the positive half cycle and that is in a logic low state when the measured current is on the negative half cycle. The method also includes determining a time difference between the first and second two-state output signals, calculating a phase difference based on the time difference, comparing the phase difference to a predetermined threshold value, opening a switch if the determined phase difference is equal to or greater that the predetermined threshold value, and, after the switch is opened, closing the switch after a predetermined amount of time has elapsed.