Manubhai R Bhavsar

US Patent:

44828535, Nov 13, 1984

Filed:

Aug 24, 1981

Appl. No.:

6/295489

Inventors:

Manubhai R. Bhavsar - Ontario CA

Assignee:

Reuland Electric Company - Industry CA

International Classification:

H02P 128
H02P 324

US Classification:

318778

Abstract:

A control circuit for a three phase induction motor includes a voltage controller having a silicon controlled rectifier in each of a first, second and third supply line connected to the motor. The control circuit further includes a first, second and third phase control means for controlling the firing angles of the respective silicon controlled rectifiers, a circuit for providing a positive ramp signal, and a circuit for providing a constant level signal. A starter circuit includes a "run" push button and a "brake" push button. The depressing of the "run" push button connects a three phase power supply to the supply lines of the voltage controller and causes the positive ramp signal to be applied to the first, second and third control means to control the firing angles of the silicon controlled rectifiers to provide a soft start for the motor. The subsequent depressing of the "brake" push button renders the second and third phase control means inoperable thus terminating the running of the motor and applies the constant level signal in place of the positive ramp signal to the first phase control means to control the firing angle of the silicon controlled rectifier in the first supply line to thereby provide a D. C. current for braking the cruising motor.