Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B - Manual (Page 111)

Publication 900-UM007D-EN-E - January 2011
Configuration & Basic Operation 3-41
7. Press the
U or D key to set the parameter to 45.
Note: This also loads the derivative time into controller memory.
Figure 3.85
8. To return to the Operation function group, press the
O
key.
Note: Proportional/Action: When PID values I (Integral time) and D
(Derivative time) are set to 0, control is executed according to
proportional operation, and the default set point becomes the center
value of the proportional band. In this case, a related parameter is
Manual Reset Value (Adjustment function group).
The following diagrams provide a basic explanation of how adjusting the P, I,
and D parameter values impact system operation.
Table 3.K — When P (Proportional Band) is Adjusted
When P is
increased The curve rises gradually, and a long
stable time is achieved, preventing
overshoot.
When P is
decreased Overshoot and hunting occur, however
the set point is quickly reached after
which the curve stabilizes.
Table 3.L — When I (Integral Time) is Adjusted
When I is
increased It takes a long time for the process value
to reach the set point. It takes time to
achieve a stable state, however there is
little overshoot/undershoot and hunting.
When I is
decreased Overshoot/undershoot and hunting occur,
and the curve rises quickly.
Table 3.M — When D (Derivative Time) is Adjusted
When D is
increased Overshoot/undershoot and stable time
are reduced; however, fine hunting occurs
on changes in the curve it self.
When D is
decreased Overshoot/undershoot increase, and it
takes time for the process value to reach
the set point.
d
45
Set
Point
PV
Set
Point
PV
Set
Point
PV
Set
Point
PV
Set
Point
PV
Set
Point
PV