ON/OFF CONTROL
The controller operates in the ON/OFF
control modebysetting theproportional band=
0.0%. The ON/OFF control hysteresis band
(CHYS) parameter eliminates output chatter
around setpoint. For heat/cool systems, the
cooling output can also be used in the ON/OFF
control by setting the relative gain = 0.0
(GAN2). Additionally, the heat/cool parameter
(db-2) determines the amount of operational
deadband or overlap between the two outputs.
The phase of the control action can be
reversed by the output control action
parameter. ON/OFF control is usually
characterizedby temperatureoscillations about
the setpoint value. Large hysteresis values
make the oscillations larger. ON/OFF control
should only be used where the constant
oscillations are acceptable.
Figure 36, OP1 On/Off Action Figure 37, OP2 On/Off Action
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