Hanna Instruments HI520 - Page 99

99 Control Modes & Algorithms
SP
Control period
PID control
Deviation
Process value
Relay out
Relay out with min.
On time control action
Min. On time
mode Low
Figure 44: PID Control Mode Low, Relay Out with Minimum On Time
To minimize overshooting, the integrative control part is zeroed as it approaches Set point.
SP
Control period
PID control
Deviation
Process value
Rela
y out
Relay out
with
0% Dead
Band Gain
Min. On time
Dead Band
mode Low
Figure 45: PID Control Mode Low, Relay Out with 0 % Dead Band Gain
To minimize overshooting, the integrative control part is diminished as it approaches Set point.
SP
Control period
PID control
Deviation
Process value
Relay out
Relay out
with
50% Dead
Band Gain
Min. On time
Dead Band
mode Low
Figure 46: PID Control Mode Low, Relay Out with 50 % Dead Band Gain