40
Adjustments:
Proportional
1) The lower the gain value (large proportional band), the less reactive the
output becomes.
Temp
2) The larger the gain value (small proportional band) over responsive
output, can lead to oscillation.
Temp
A proportional band which is correct approaches the set point as fast as
possible while minimizing overshoot.
If a faster response is desired and process overshoot is not a problem,
increase the gain value (over-damped system). If overshoot can’t be
tolerated, decrease the gain value (under-damped system.)
Integral
Integral action eliminates offset by adding to or subtracting from the output
of the proportional action alone.
1) Short integral time means the controller corrects for offset quickly. If too
short, the controller would react before the effects of previous output
shifts, due to dead time or lag, are complete, could cause oscillation.
Temp
P.B. too large
TIME
S.P.
P.V.
OFFSET
P.B. too small
TIME
S.P.
P.V.
TIME
P.B.
S.P.
"I" is too short
Summary of Contents for M2B
Page 1: ... Rev A ...
Page 49: ...48 ...