OVERLOAD DETECTION DEVICE AND OVERLOAD DETECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide an overload detection device capable of detecting an overload by automatically selecting a threshold value for overload detection according to an AC voltage to be applied to a motor.SOLUTION: An overload detection device comprises a current detection unit 13b which detects current flowing in a three-phase motor 3; a threshold value definition unit 13a which defines a plurality of threshold values for detecting an overload of the three-phase motor 3; and a comparison unit 13f which compares the current detected by the current detection unit 13b with one threshold value defined by the threshold value definition unit 13a. This device further comprises: a voltage discrimination unit 13d which discriminates a level of the voltage to be applied to the three-phase motor 3; and a threshold value selection unit 13e which selects one threshold value defined by the threshold value definition unit 13a according to the discrimination results of the voltage discrimination unit 13d.