C6-8
IM 34M06H62-02E 2nd Edition : June 2008-00
C6.5 Manual Adjustment of PID Constants
The following formula shows the relationship between the output and the PID constants.
Bear this formula in mind when adjusting PID constants manually.
To perform manual adjustment of PID constants, follow steps (2) to (5) given below.
e: Deviation PB: Proportional band TI: Integral time
TD: Derivative time
Procedure for adjusting PID constants manually
(1) (If possible, use auto-tuning. Otherwise do the following:)
(2) Adjust PB, TI and TD, in this order. Change the values gradually
whilst checking and writing down the result.
(3) Start with a large PB and decrease it gradually. If oscillations
appear in the PV, stop and increase PB by a few seconds.
(4) Start with a large TI and decrease it gradually. If long oscillations
appear in the PV, stop and increase TI by a few seconds.
(5) Start with a small TD and increase it gradually. If short oscillations
appear in the PV, stop and decrease TI by a few seconds.
Output = e +
100
PB
1
TI
+ TD
e
d
dt
edt
Figure C6.9 Procedure for Manual Adjustment of PID Constants
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