Watlow CLS200 - Manual (Page 175)

CLS200 Series User’s Guide Chapter 8: Tuning and Control
Doc.# 0600-3050-2000 Watlow Anafaze 159
Reverse and Direct Action
With reverse action an increase in the process variable
causes a decrease in the output. Conversely, with direct ac-
tion an increase in the process variable causes an increase
in the output. Heating applications normally use reverse
action and cooling applications usually use direct action.
Setting Up and Tuning PID Loops
After installing your control system, tune each control loop
and then set the loop to automatic control. When tuning a
loop, choose PID parameters that will best control the pro-
cess. This section gives PID values for a variety of heating
and cooling applications.
NOTE! Tuning is a slow process. After adjusting a
loop, allow about 20 minutes for the change
to take effect.
Proportional Band (PB) Settings
Table 8.1 shows proportional band settings for various
temperatures in degrees Fahrenheit or Celsius.
Table 8.1 Proportional Band Settings
As a general rule, set the proportional band to 10% of the
setpoint below 1000
˚ and 5% of the setpoint above 1000 ˚ .
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