CURRENT DISPLAY AND OVER CURRENT PROTECTION APPARATUS FOR ELECTRIC MOTOR

Japanese Patent JP2588652

B2

PURPOSE: To provide a current display and over current protection apparatus for an electric motor which uses a single current sensor.
CONSTITUTION: A microcomputer is provided to execute the following: a command for a low multiplying rate is issued to a multiplying circuit 4 when the current of an electric motor is not beyond its rated value in accordance with a current sensor 3 to detect the current of the electric motor 1, a display 6 to display the current information, a breaker 2 to open the source supply circuit for the electric motor 1, the multiplying circuit 4 to receive the output signal from the current sensor 3 and output it after changing the multiplying factor of the inputted signal, an A-D converter 5 to convert such an output signal into digital data, and the output of this A-D converter 5, a command for a low multiplying rate is issued to a multiplying circuit 4 when the current of an electric motor is not beyond its rated value; then, the output data from the A-D converter is numerically coded to allow the display 6 to display the information on the current value; and if the current is beyond the rated value, a command for a high multiplying rate is issued to the multiplying circuit 4 and at the same time, to numerically code the output data from the A-D converter 5 thereby to enable the display 6 to display the information on an over current, and when the product of the numerically coded current value by the time exceeds a given value, a command is issued to the breaker 2 to open its circuit.

NAKAJIMA KAORU
SUZUKI TAKASHI

JP20824891A

March 05, 1997

August 20, 1991

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EBARA SEISAKUSHO KK
KASUGA DENKI KK

G09F9/00; G01R15/09; H02H3/08; H02H7/085; H02P29/00; H02P29/40; (IPC1-7): H02H7/085; G01R15/09; H02H3/08

JP2168812A
JP4722173A
JP52134779A
JP5497463A
JP6015671U

Kazuo Sato (3 others)

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