14
Tuning
Procedures
This tuning method may be used if the spread between ambient temperature and process operating
temperature is small. For best results, the use of a recording device is suggested when tuning with this
method.
1) Disable any cooling device used.
2) Apply power and place the controller in Standby by pressing and holding the Mode key for four
seconds.
3) Using Raise or Lower key, adjust setpoint to desired value.
4) Access menu level “02” following instructions given previously.
5) Using the Parameter/Access key, index to Heat Gain [ Gn.o1 ]. Select [ 01 ].
6) Index to Gain Ratio [ Gr.o2 ] and select [ 1. 0 ]. Note: Gain ratio [ Gr.o2 ] is the cooling gain expressed
as a factor of the heating gain. Example - with a heat gain [ Gn.01 ] = 100 and a Cooling Gain = 50, then
Gain ration [ Gr.o2 ] = 0.5
7) Index to Rate [ rAtE ] and select [ 00 ].
8) Index to Reset [ rSEt ] and select [ 00 ]. Note: In order to set Reset to [ 00 ], Rate must first be set to [
00 ].
9) Change to menu level “03”.
10) Index to Cycle Time 1 [ CY.t1 ] and select the timebase, in seconds, appropriate to the device being
controlled.
11) Repeat for Cycle Time 2 [ CY.t2 ].
12) Change to menu level “05”.
13) Set Cooling Type [ CoL.t ] to [ nor ].
14) Press the Mode key once. Setpoint Value will be displayed. The recording device should now be
tracking process temperature.
15) Double the Gain [ Gn.o1 ] until a small, sustained oscillation is visible on the recording device’s trace.
16) Measure the period of one cycle of oscillation (“T” on the diagram below).
17) Divide the period of oscillation (T) by eight (8). The resulting number is the correct Rate time [ rAtE ] in
seconds. Multiply this number by four. This is the correct Reset time [ rSEt ] in seconds.
18) Multiply the gain (from step #15) by 0.6 and enter this number as Gain [ Gn.o1 ].
19) Enable the cooling device. Note: If overcooling exists, decrease the Gain Ratio [ Gr.o2 ] in steps of 0.1
until temperature oscillation stops. If cooling is sluggish, increase the Gain Ratio in steps of 0.1 until
optimum results are achieved.
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