Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1998-01-20
1999-03-16
Wysocki, Jonathan
Electricity: motive power systems
Induction motor systems
Primary circuit control
H02P 126
Patent
active
058834869
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.
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Earhart, Jr. Walter
Hanson Rolf M.
Johnson Dwayne L.
American Standard Inc.
Beres William J.
Ferguson Peter D.
O'Driscoll William
Wysocki Jonathan
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