Walchem W600 Series Instruction Manual page 65

and the control elements (pump, valves, etc.) will be sized properly so that the output never reaches its minimum
or maximum limit during normal control operations. But with this wind-up suppression feature, overshoot will
be minimized should that situation occur.
Output Details
The details for this type of output include the pulse rate in %, HOA mode or Interlock status, input value, current
integral, current and accumulated on-times, alarms related to this output, relay type, and the current control
mode setting.
Set Point
Gain
Proportional Gain
Integral Time
Integral Gain
Derivative Time
Derivative Gain
Reset PID Integral
Minimum Output
Maximum Output
Maximum Rate
Input
Direction
Input Minimum
Input Maximum
Gain Form
Numeric entry of a process value used as a target for PID control. The default value,
units and display format (number of decimal places) used during data entry are defined
based on the Input channel setting selected.
When the Gain Form setting is Standard, this unitless value is multiplied by the total
of the proportional, integral, and derivative terms to determine the calculated output
percent.
When the Gain Form setting is Parallel, this unitless value is multiplied by the normalized
error (current process value versus set point) to determine the proportional component of
the calculated output percent.
When the Gain Form setting is Standard, this value is divided into the integral of the
normalized error (area under the error curve), then multiplied by the Gain to determine
the integral component of the calculated output percent.
When the Gain Form setting is Parallel, this value is multiplied by the integral of the
normalized error (area under the error curve) to determine the integral component of
the calculated output percent.
When the Gain Form setting is Standard, this value is multiplied by the change in error
between the current reading and the previous reading, then multiplied by the Gain to
determine the derivative component of the calculated output percent.
When the Gain Form setting is Parallel, this value is multiplied by the change in error
between the current reading and the previous reading to determine the derivative com-
ponent of the calculated output percent.
The PID Integral Value is a running total of the accumulated area under the error curve
(Current Integral). When this menu option is selected, this total is set to zero and the
PID algorithm is reset to its initial state.
Enter the lowest possible pulse rate as a percentage of the Maximum Stroke Rate set
below (normally 0%).
Enter the highest possible pulse rate as a percentage of the Maximum Stroke Rate set below.
Enter the maximum pulse rate that the metering pump is designed to accept (10 – 480
pulse/minute range).
Select the sensor to be used by this relay
Set the control direction. This setting is used to determine the sign of the calculated error
(current process value versus set point) and allows flexible control with only positive
values for all PID tuning parameters.
The low end of the sensor input range, used to normalize errors into percent of full scale
units. These values are set to the nominal range of the selected input sensor by default.
The high end of the sensor input range, used to normalize errors into percent of full scale
units. These values are set to the nominal range of the selected input sensor by default.
Select the PID Equation Format used to enter tuning parameters.
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