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. 16, 1999
Filed:
Jan. 20, 1998
Walter Earhart, Jr, La Crosse, WI (US);
Dwayne L Johnson, La Crescent, MN (US);
Rolf M Hanson, Onalaska, WI (US);
American Standard Inc., Piscataway, NJ (US);
Abstract
An apparatus and method for soft-starting a three-phase motor for connection to a three-phase power source for driving a three-phase motor. Soft-start provides a way to reduce the amount of starting torque and current during starting conditions. First, second, and third conductors are connected between a three-phase power source and a three-phase motor. A power contactor interrupts and provides current along the three conductors. A phase-shifting element for shifting the phase of the power signal normally outputted from the first conductor to match the phase of the power signal normally outputted from the third conductor is connected between the first and third conductors. A switching apparatus having first and second switch elements is connected between the phase-shifting element and the third conductor. When the first switch element is closed, current flows from the first conductor to the motor via the phase-shifting element. When the second switch element is open, no current flows from the third conductor to the motor directly. In this mode, the motor is running on single-phase power. When the states of the first and second switch elements are flip-flopped, the motor runs on three-phase power. The first and second switch elements' states are controlled by a control element which energizes the switching apparatus upon the occurrence of a triggering event.