| 摘要 |
Method of protecting an electric motor against overloads, in which the rotational speed of the motor is monitored with respect to a preselected reference value and, if the rotational speed of the motor is lower than the reference value, the voltage applied to the motor is cut off so as to cease the drive to this motor and to protect it against overheating or damage. The rotational speed of the motor is detected in the form of a number of pulses in order to monitor an associated pulse frequency, this pulse frequency being, for example, converted into an output voltage level which constitutes one of the elements for detecting the state of overload of the motor without having recourse to a microcomputer.
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