5 PID Control
Mk8 MM Manual Page | 120
5 PID CONTROL
The standard control algorithm used by the Mk8 MM to control the fuel/air ratio is PID control; Proportional-
Integral-Derivative control. The control algorithm compares the actual measured temperature or pressure
and compares it to the user specified setpoint temperature or pressure. Depending on the measured and
setpoint values, the MM’s PID control will then either modulate the burner up or down. The rate of change or
speed of the burner modulation in relation to changes in measured temperature or pressure is dependent on
the settings of the PID control. The PID control action is the sum of the “Proportional” + “Integral” +
“Derivative” actions of the PID control. Each contributes to how the 3 term PID control modulates the burner
and each operates as outlined below.
Most applications can be controlled adequately using just the Proportional and Integral settings; a PI control
setup.
5.1 Proportional Band
The Proportional term is specified in option 6 by defining the “Proportional band” (P-Band). The P-Band is
simply an offset from the setpoint pressure or temperature. Outside and below the P-Band, the MM’s PID
control will modulate the burner at maximum flame, upon reaching the P-Band, it will then modulate the
burner linearly down (see option 6).
Figure 5.1.i Proportional Band
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