Abstract
When malfunction occurs at the automatic control system in plant, human operator is expected to control by manual switching. The typical case is to change over the state of the system, say “change-over type”. This paper focuss on adjustment operation at “change-over type”. Observing the adjustment operation, operator performs several switching of the ON/OFF controller. Then, the time which operator keep the controller On-state at one switching (τstep), and the number of switching at adjustment operation (N) are measured. As the result, each τstep is neighborhood of 0.075 (sec). And N is varied when time constant and gain increased/decreased, but the cause is the threshold for deviation between controlled quantities. Constructing the model for N in consideration of effect by threshold, the number of switching at operator's plan is 4 times under every experimental conditions. Combining these facts, operator's strategy for adjustment operation at “change-over type” is not affected by such factors as time constant and gain.
