Unipulse F805AT-BC Operation Manual page 99

6.SETTING AND ADJUSTMENT OF READING
Integral (I)
Integral action, in concert with proportional action, has an effect of diminishing offset
with time, resulting in better fit between the flow and target values.
Integral (I) represents the intensity of integral action. Shorter integral time provides
stronger integral action, and if it becomes excessive, too strong a corrective action
gives rise to system hunting, as in the case of proportional action.
F805AT-BC is shipped with factory-set initial integration time (I): the user can use this
value unless additional tuning becomes necessary.
* Empirically, integral (I) bandwidth between 4.00 and 15.00 sec is recommended
Operation
MODE
Range: 0.01 – 999.99 sec (5 digits, decimal place fixed to 2
Differential (D)
Proportional and integral action tends to become slow because they are corrective
actions based on the control results. Differential action is a useful addition to enhance
system response: it gives rise to corrective action proportional to the magnitude of
deviation. Differential action reacts with magnitude proportional to the changing rate of
disturbance, providing quicker restoration to previous state.
Differential (D) represents intensity of differential action and it is the time required for
differential control rate to achieve the same value as proportional action. Longer
differential time provides stronger corrective action, and if it becomes excessive, tends
to produce tiny and quick system hunting.
* Empirically, differential (D) bandwidth between 0.00 – 10.00 sec is recommended.
Setting 0.00 second to this parameter disables differential action (PI control).
Control with too small differential action
Operation
MODE
Range: 0.00 – 99.99 sec (4 digits, decimal place fixed to 2
84
→ EACH CODE → INTEGRAL (I)
Differential (D) action
not used
Differential (D)
too small
EACH CODE DIFFERENTIAL (D)
→ →
nd
position)
Differential (D) action
not used
Optimum
differential (D)
Control with optimum differential action
nd
position)