| 摘要 |
PURPOSE:To prevent the damage of an apparatus at the time of the abnormal lowering of the number of revolution by transmitting an abnormal signal and operating a relay when the frequency of a generated signal by a rotational detector is lower than the reference signal frequency. CONSTITUTION:A generated signal by the revolution of an air blower is obtained by a rotational detector 1. A reference signal is generated by an integrated circuit 2, and an abnormal signal is transmitted when the frequency of the generated signal is lower than the frequency of the reference signal. Consequently, a relay 3 is changed over to the (a) side, a power supply for the air blower is interrupted, and an alarm device is operated. Accordingly, when the revolution of the air blower is stopped or the number of revolution is lowered abnormally, the power supply is interrupted, and an alarm is given, thus preventing the damage to a motor and an apparatus. |
