Athena Technologies 16C - Manual (Page 32)

28
Manual Tuning
Manual Tuning Procedure
(Zeigler-Nichols PID Method)
This tuning method may be used for non-temperature control
processes or if the spread between ambient temperature and
process operating temperature is small. For best results, the
use of a recording device is required when tuning with this
method.
1) For temperature control processes, disable any cooling
device used.
2) With the power off and the controller NOT in the Key
Lockout security level, apply power and immediately put
the controller in Standby mode by pressing the Mode/
Enter key for three seconds, the Raise key until
appears and press the Mode/Enter key again.
3) If you have a direct-acting output, it must be disabled
before proceeding further = .
4) Under the Control menu, make sure that the derivative
term , the offset term , and the integral
term are all set to zero, and the proportional
band or is set to the maximum setting.
5) Adjust setpoint to the desired value with the Raise/Lower
keys.
6) Press the Mode/Enter key for four seconds, the Raise
key twice , and the Mode/Enter key again to
return the controller to normal operation.
While some processes
other than heat or
cool applications may
respond successfully to
autotuning procedures,
the controller may need
to be manually tuned
for non-temperature
processes.
7) While monitoring the recording device, decrease the
proportional band value by repeatedly halving the
value until a small, sustained temperature oscillation is
observed. Measure the period of one cycle of oscillation
(“T” on the diagram below).
8) Divide the period of oscillation (T) by eight. The resulting
number is the correct Derivative time in seconds.
Multiply this number by four. This is the correct Integral
time in seconds.
9) Multiply the bandwidth value obtained in Step 7 by 1.66
and enter this as the new proportional band value.
T