Watlow 12LS Controller - Manual (Page 96)

5-5
5.2.5 PID TUNING CONSTANTS
PROPORTIONAL BAND SETTINGS
THE FOLLOWING TABLE REPRESENTS AN AVERAGE SETTING FOR THE PB IN
RELATIONSHIP TO THE SETPOINT OF THE CONTROLLER WITH A TEMPERATURE
INPUT:
TEMPERATURE PB TEMPERATURE PB
SETPOINT SETPOINT
-100 TO +100 20 1600 TO 1699 100
+100 TO +199 20 1700 TO 1799 105
200 TO 299 30 1800 TO 1899 110
300 TO 399 35 1900 TO 1999 120
400 TO 499 40 2000 TO 2099 125
500 TO 599 45 2100 TO 2199 130
600 TO 699 50 2200 TO 2299 135
700 TO 799 55 2300 TO 2399 140
800 TO 899 60 2400 TO 2499 145
900 TO 999 65 2500 TO 2599 150
1000 TO 1099 70 2600 TO 2699 155
1100 TO 1199 75 2700 TO 2799 160
1200 TO 1299 80 2800 TO 2899 165
1300 TO 1399 85 2900 TO 2999 170
1400 TO 1499 90 3000 TO 3099 175
1500 TO 1599 95 3100 TO 3199 180
As a general rule use 10% of the SP below 1000 and 5% above 1000 for a starting point in
setting the PB.
INTEGRAL (TI) VERSUS RESET REPEATS/MINUTE (R/M)
RESET R/M = 60/TI
TI (SEC.) R/M TI (SEC.) R/M TI (SEC.) R/M
30 2.0 150 .40 300 .20
45 1.3 180 .33 400 .15
60 1.0 210 .28 500 .12
90 .66 240 .25 600 .10
120 .50 270 .22
As a general rule use 60, 120, 180, or 240 for TI.
DERIVATIVE (TD) VERSUS RATE MINUTES (RM)
RATE = TD/60
TD (SEC.) RM TD (SEC.) RM TD (SEC.) RM TD (SEC.) RM
5 .08 20 .33 35 .58 50 .83
10 .16 25 .41 40 .66 55 .91
15 .25 30 .50 45 .75 60 1.0
As a general rule set TD to be 15% of TI.