| 摘要 |
PURPOSE: A device for automatically braking power at the time of overload of a motor of an air blower is provided to prevent a fire generated by overheat of the motor by automatically breaking driving power supplied to the air blower when overload occurs due to decrease of rotational force. CONSTITUTION: A device for automatically braking power at the time of overload of the motor of the air blower includes a magnet(10) mounted at a side of a rotating shaft(4), a Hall element(20) outputting voltage pulse every change of polarity of the magnet, a power supply part(32) outputting stable DC voltage and supplying driving power to a circuit of a rear end, a relay switch(SW) for supplying and blocking driving power to and from a motor(3), a display part(38) sending lighting of a lamp and buzzer to a user if overload of the motor is detected, a relay(50) for blocking driving power of the motor by converting an off contact point of the relay switch if the overload of the motor is detected, a signal converter(34) converting voltage pulse output from the Hall element into analog signal, a comparative circuit(35) comparing voltage value output from the Hall element with a standard voltage value, a signal transferring part(36) for transferring output control signal of the comparative circuit, a latch circuit(37) for continuously driving the display part and the relay until power is supplied again, and an initializing circuit(39) delaying output power during a prescribed period of time to stabilize and initializing the latch circuit.
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