JPS5794802A - Process controller - Google Patents

Abstract

PURPOSE:To avoid a breakdown within a pipe which is caused by the water hammering and at the same time to increase the reliability, by controlling the output of the rotational frequency of a pressure feeder when the rotational frequency and the jetting pressure of the pressure feeder are decided identical with those measured before the occurrence of an instantaneous stop during the occurrence of the instantaneous stop. CONSTITUTION:The rotational frequency of a pump is calculated from the differential between the set value of the jetting pressure and the signal fetched by a pressure detector and by resistances 21 and 22, a capacitor 23, an amplifier 25 plus resistances 24 and 26. A relay 40 works during a period from the occurrence of an instantaneous stop through a moment when both the rotational frequency and the jetting pressure are reset within the deviation. Thus contacts 37 and 38 are opened; while a contact 39 is closed. Accordingly a command for the rotational frequency of a pump which is calculated by the amplifier 25 is not delivered since the contact 37 is opened. The data in an analog data storage circuit 41 has no change either since the contact 38 is opened. Then the data of the circuit 41 is delivered since the contact 39 is closed. The relay 40 stops its working when the rotational frequency and the jetting pressure of the pump are reset to the value within the deviation after the occurrence of the instantaneous stop. Thus the contacts 37 and 38 are closed with the contact 39 opened respectively to secure the state obtained before the occurrence of the instantaneous stop.