Watlow Series 982 - Manual (Page 110)

8.2 WATLOW Series 982 User’s Manual Tuning, Alarms and Error Codes, Chapter 8
Tuning
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To start auto-tuning:
1. Press the Mode key
until the AUt prompt appears in the lower display.
2. Use the Up/Down key to select Pid in the upper display.
3. Press the Display key. While the control is in the tuning mode, the
lower display alternately displays the normal information and the tunE
prompt. The time between alternations is 1 second.
4. When tuning is complete, the displays return to their previous state
and AUt reverts to OFF. The 981/982 installs appropriate PID tuning
parameters and saves them in non-volatile memory.
To abort auto-tuning either reset the AUt prompt to OFF, or cycle power
off and on. In all cases, aborting auto-tune restores all values to those pre-
vious to auto-tuning.
Manual Tuning
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For optimum control performance, tune the Series 981/982 to your ther-
mal system. The tuning settings here are for a broad spectrum of applica-
tions; your system may have somewhat different requirements. NOTE:
This is a slow procedure, taking from minutes to hours to obtain optimum
values.
NOTE:
Tune heating outputs at a set point above ambient process value.
Tune cooling outputs at a set point below ambient process value.
NOTE:
1. Apply power to the Series 981/982
and enter a set point. Begin with
these Operation parameters: Pb = 1, rE/It = 0.00, rA/dE = 0.00, Ct =
5.0,
AUT
= OFF.
2. Proportional Band Adjustment: Gradually increase Pb until the
upper display process value stabilizes at a constant value. The process
value will not be right on set point because the initial reset value is 0.00
repeats per minute. (When Pb = 0, rE/It, rA/dE and cycle time are
inoperative, the 981/982 functions as a simple ON/OFF control.) The
HYS prompt determines the switching differential value.
3. Reset/Integral Adjustment: Gradually increase rE, or decrease It until
the upper display process value begins to oscillate or “hunt.” Then slowly
decrease rE or increase It until the upper display stabilizes again near
set point.
4. Cycle Time Adjustment: Set Ct as required. Faster cycle times some-
times achieve the best system control. See Chapter 9, “Burst Firing,” for
more information. However, if a mechanical contactor or solenoid is
switching power to the load, a longer cycle time may be desirable to
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CAUTION:
If a mechanical
relay or contactor is
switching power to
the load, a longer
cycle time may be
desirable to mini-
mize wear on the
mechanical compo-
nents. Typical life of
a mechanical relay
is 100,000 cycles.
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CAUTION:
If a mechanical
relay or contactor is
switching power to
the load, a longer
cycle time may be
desirable to mini-
mize wear on the
mechanical compo-
nents. Typical life of
a mechanical relay
is 100,000 cycles.
NOTE:
You cannot access
the AUt prompt
while the controller
is in run mode.