| 摘要 |
PROBLEM TO BE SOLVED: To provide an abnormality detector for water-quantity sensor that can detect the abnormal state of a water-quantity sensor in an early state. SOLUTION: The water-quantity sensor 7 has an impeller which is rotated by a water flow passing through a water supply pipe 5 and a magnetic sensor which outputs a pulse signal of the period corresponding to the number of revolutions of the impeller and outputs a pulse signal of a frequency proportional to the quantity of water supplied to the pipe 5. An abnormality detecting means 41 for water-quantity sensor installed to a controller 2 detects the period of the pulse signal outputted from the sensor 7 at every pulse and, when the period T of detected one pulse changes beyond the range (1/2TB<=T<=2TB) from 1/2 to two times of the average period TB of the six pulses immediately before the pulse, notifies the abnormal state of the sensor 7 by means of a loudspeaker 34 and a buzzer 35.
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