Derivative settings – Watlow CPC400 User Manual
Page 100
Chapter 4: Tuning and Control
CPC400 Series User’s Guide
86
Watlow Anafaze
Doc. 0600-2900-2000
Table 4.2
Integral Term and Reset Settings
As a general rule, use 60, 120, 180 or 240 as a starting val-
ue for the integral.
Derivative Settings
The controller’s derivative parameter is programmed in
seconds. Some other products use a derivative term called
rate programmed in minutes. Use the table or the formula
to convert parameters from one form to the other. Table 4.3
shows derivative versus rate. Rate = Derivative/60.
Table 4.3
Derivative Term Versus Rate
As a general rule, set the derivative to 15 percent of inte-
gral as a starting value.
NOTE!
While the basic PID algorithm is well defined and
widely recognized, various controllers implement
it differently. Parameters may not be taken from
one controller and applied to another with opti-
mum results even if the above unit conversions
are performed.
Integral
(Seconds/Repeat)
Reset
(Repeats/Minute)
Integral
(Seconds/Repeat)
Reset
(Repeats/Minute)
30
2.0
210
0.28
45
1.3
240
0.25
60
1.0
270
0.22
90
0.66
300
0.20
120
0.50
400
0.15
150
0.40
500
0.12
180
0.33
600
0.10
Derivative
(seconds)
Rate
(minutes)
Derivative
(seconds)
Rate
(minutes)
5
0.08
35
0.58
10
0.16
40
0.66
15
0.25
45
0.75
20
0.33
50
0.83
25
0.41
55
0.91
30
0.50
60
1.0