Hach sc200 User Manual page 40

• Frequency Control Function (refer to
Option Description
Set mode Auto—The relay works as a PID controller.
Manual—the signal is controlled by the user through manual adjustment of the % change
value. This option is shown as Manual Output after the manual set mode is selected.
Phase Reverses the leading sign of the control deviation for the PID controller (default: Reverse).
The phase selects whether the relay will operate at the first part of a cycle (direct phase) or
the second part (reverse phase).
Set setpoint Sets the process value which is controlled by the PID controller.
Dead zone In this set range, the PID controller does not take action to change the output frequency
until within the limits of the dead zone.
Pulse width Sets the cycle duration (0-600 seconds) of the PWM output signal. (default: 0.5 seconds)
The cycle duration is equal to the duty cycle of the output signal.
Minimum Sets the minimum number of pulses per minute at which the relay can operate. Range:
pulses 0.001–4.000 (default: 1.000)
Maximum Sets the maximum number of pulses per minute at which the relay can operate. Range:
pulses 0.001–60.000 (default: 04.000). This value cannot be set lower than Minimum Pulses value.
Prop band Sets the proportional part of the PID controller. The proportional part of the controller
supplies an output signal which is linearly dependent to the control deviation. The
proportional part reacts on any changes at the input but starts to oscillate easily if the value
is set high. The proportional part cannot fully compensate for disturbances.
Integral Sets the derivative part of the PID controller (default: 000 minutes). The integration part of
the controller generates an output signal. The output signal increases linearly if the control
deviation is constant. The integration part responds slower than the proportional part and
can fully compensate disturbances. The higher the integration part, the slower it responds.
If the integration part is set too low, it starts to oscillate.
38 English
Figure 25)