| 摘要 |
<p>PURPOSE:To make it possible to lessen the frequency of control operation easily without making control unstable by performing the control operation for a certain time even when the controlled variable of a controlled system varies beyond a dead zone. CONSTITUTION:Once opening setpoint Vp vaires until -d>-epsilon, comparison recording controller 6 closes open command contact 7R. Here, (d) is a dead zone and epsilon is a deviation value. While contact 8Ra is closed by closing contact 7R, time adjusting relay 9RT is excited. With contact 8Ra closed, on the other hand, driving circuit 10 drives electric motor 2 to close valve 1. When actual opening value VF exceeds setpoint Vp by dead zone (d), namely, when epsilon>d, close command contact 7L is closed. Then, relay 8L is excited as long as the time limit time of time adjusting relay 9LT. For the purpose, driving circuit 10 reverses electric motor 2 to close valve 1. Thus, when valve opening value VF varies beyond dead zone (d), on-off operation is carried out for a certain time set to the time adjusting relay.</p> |
