| 摘要 |
PURPOSE:To ensure safety of a device by stopping a motor when a condition discriminating means detects abnormal conditions, and operating a heat generating means when it detects low temperatures. CONSTITUTION:A condition discriminating means 6 is installed to discriminate the condition of a well pump and turn on/off the first switching circuit 2 according to the condition discrimination output. And a temperature sensor 7 to detect the temperature near a pump motor, and a low temperature detecting circuit 8 to turn on the second switching circuit 5 when the temperature is under a fixed value are also installed. Therefore, it is possible to automatically stop operation of the well pump motor when the temperature is high or there is excess current, and to prevent freezing by raising the temperature around the motor when the temperature is low.
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