Watlow CLS - Manual (Page 111)

PID Tuning and Control
CLS User’s Guide 103
Setting Up and Tuning PID Loops
After you have installed your control system, tune each control loop and
then set the loop to automatic control. (When you tune a loop, you
choose PID parameters that will best control the process.) If you don't
mind minor process fluctuations, you can tune the loop in automatic
control mode. This section gives PID values for a variety of heating and
cooling applications.
If you don't know the PID values that are best for your process, try the
CLS Autotune feature. The autotune feature is accessible from the
controller's Man/Auto key. (For more information about Autotune, see
Using the CLS.)
NOTE
Tuning is a slow process. After you have adjusted a loop,
allow about 20 minutes for the change to take effect.
Proportional Band (PB) Settings
The table below shows PB settings for various temperatures in
degrees F.
As a general rule, set the PB to 10% of the setpoint below 1000 º and 5%
of the setpoint above 1000 º . This setting is useful as a starting value.
Temperature
Setpoint
PB
Temperature
Setpoint
PB
Temperature
Setpoint
PB
-100 to 99 20 1100 to 1199 75 2200 to 2299 135
100 to 199 20 1200 to 1299 80 2300 to 2399 140
200 to 299 30 1300 to 1399 85 2400 to 2499 145
300 to 399 35 1400 to 1499 90 2500 to 2599 150
400 to 499 40 1500 to 1599 95 2600 to 2699 155
500 to 599 45 1600 to 1699 100 2700 to 2799 160
600 to 699 50 1700 to 1799 105 2800 to 2899 165
700 to 799 55 1800 to 1899 110 2900 to 2999 170
800 to 899 60 1900 to 1999 120 3000 to 3099 175
900 to 999 65 2000 to 2099 125 3100 to 3199 180
1000 to 1099 70 2100 to 2199 130 3200 to 3299 185