| 摘要 |
PURPOSE:To suppress the excessive pressure by operating a pump at the preset rotating speed when the detection signal of a pressure sensor at the discharge side drops or rises abnormally. CONSTITUTION:A confirming circuit 12 judges that the output signal of a pressure sensor 4 is outside the normal preset range, the control pressure of a pressure regulator 7 is switched, and the control output of a stand-by operating circuit 10 is inputted as the speed command signal of a variable-speed device 6. A pump 2 is operated at the running speed set lower than the running speed by a commercial power supply 1. Accordingly, the excessive pressure when an abnormality occurs can be suppressed, and the operating power can be reduced.
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