10
temperature overshoot by responding its rate of change. The larger the number is, the
faster the action will be, e.g. when the door of oven is opened, the temperature will drop
at very high rate. The derivative action change the controller output based on the rate of
change rather than the net amount of change. This will allow the controller to act sooner.
It will turn the heater to full power before the temperature drops too much.
•
t
, cycle rate. The unit is in seconds. This unit determines how long for the controller to
calculate each action. For example, if T is set to 10 seconds, when the controller decides
the output should be 10%, it will turn on the heater 1 second for every 10 seconds. This
parameter should set at 2 second for heating with an electric heater. When controlling a
solenoid valve or a compressor of refrigerator, the T should be set to 10-20 to reduce the
frequency of on/off.
This group of parameters can be accessed by input code 166. Figure 6 is the flow chart that
shows how they can be changed. Press and hold SET key for 3 seconds until LED displays
“LoCK.” Then release the SET key. The display will show “0”. To get into parameters setting
mode, you need to key in the pass code. Use “+” and “-“keys to adjust the display to 166 and
press SET. The LED will show “P” for a second and then its P setting value, Use “+” and “-” keys
to change the setting. When finished, press the SET again to confirm the change. The display
will show the “I “ for a second and its I setting value next, use the same “P” setting procedure to