SHAFT TORQUE LIMITING DEVICE FOR INDUCTION MOTOR Russian patent published in 2005 - IPC

FIELD: electrical engineering; limiting induction-motor shaft torque.

SUBSTANCE: proposed device has switching unit, current transformer and potential transformer inserted in motor stator circuit, and amplifier. Newly introduced in device are two matching units, dc bridge with standard resistors inserted in its two arms and resistors of resistive optocouplers, in its other arms. Current transformer output is connected through first matching device to photodiode of first resistive optocoupler; potential transformer output is connected through second matching device to photodiode of second resistive optocoupler. Output of dc voltage supply is connected across two diagonally opposite power terminals of dc bridge whose output diagonally opposite terminals are connected to input of amplifier; output of the latter is connected through threshold unit to switching unit input.

EFFECT: enhanced precision and reliability of shaft torque limiting; enhanced noise immunity.

1 cl, 2 dwg