| 摘要 |
A motor protecting method having an improved function and a system for performing the protecting method are provided to determine an abnormal state of a motor by operating heat accumulated in proportion to a change of a load state and an operational time of the motor, thereby increasing accuracy in a cutoff operation of the motor. A current detector(120) detects currents applied to a motor(110). An abnormal current detector(140) detects an abnormal current applied to the motor(110) by using the detected currents. A power spectrum analyzer(150) amplifies a current change of a specific band capable of sensing a current change among the detected currents, and detects fine changes of the motor(110). A thermal accumulative operator(130) detects an abnormal state of the motor(110) by reducing accumulated heat capacities according to an actuating time of the motor(110). A controller(160) controls the first alarm generator(170) as a preliminary alarm and the second alarm generator(180) as a main alarm to subdivide alarms into the preliminary alarm and the main alarm when the motor(110) is abnormal, to display the alarms, and controls a control signal generator(200) for cutting off power of the motor(110) by outputting a signal to a motor power cutoff unit(190) if outputted values of the operator(130) and the detector(140) reach abnormal setup values.
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