| 摘要 |
PURPOSE:To provide an automatic control system capable of suppressing the mechanical action thereof to the minimum and obtaining high control results with high reliability and at low cost by allowing the automatic control system used in an air-conditioning system or the like to comprise adjusting means for delivering a three-position output depending on the size of a deviation between a signal obtained at the detection end and a target signal and the polarity, and operating means comprising a motor controlled at a corresponding speed between the limit values in accordance with the output. CONSTITUTION:A three-position output adjustor 20 is switched to any of contancts (a)-(c) by the output of a comparison part 20a. When a signal obtained at a detection end 1 becomes smaller than a target signal by a predetermined value or more, a switch 20b is changed over from the contact (b) to the contact (a) by the output of the comparison part 20a. This signal is added to an inverter 14 as a frequency signal to a increase the rotational speed of the motor for actuating a pump 8. When a difference between the above described signal and the target value signal becomes less than a predetermined value, the switch 20a is changed over from the contact (a) to the contact (b), and a pulse generator 30 stops its operation. The output of D-A 24 is inputted to an uppermost limiter and a lower-most limiter, and the upper limit and lower limit voltages are mutually monitored. When the output voltage exceeds the limit, the output signal keeps the maximum value or the minium value, and determines the maximum frequency and the minimum frequency of the alternating current of the output of the inverter 14. |
