PID

Configuring Unit Ventilator PID

Use the Unit Ventilator PID page to set PID settings.

Purpose

Adjust PID (Proportional Integral Derivative) control parameters for the Unit Ventilator Controller.

Mode

Off-line or On-line

Equipment Damage Possible

Can cause short cycling of compressors or wide swings in space temperature and excessive overdriving of modulating outputs.

If large or frequent change to PID control parameters is made, it is possible to cause equipment problems such as short cycling compressors (if the stage minimum run times were disabled). Other problems that can occur include wide swings in space temperature and excessive overdriving of modulating outputs.

The default values provide proper control for most applications. If the PID parameters require adjustment away from these values, use caution to ensure that equipment problems do not arise. If any change to PID control parameters is made, the adjustments should be gradual. After each change, allow the system to stabilize so the effects are accurately observed. Make further refinements as needed until the system is operating as desired.

If the default values are changed and you want to reset them, add a second Unit Ventilator Controller to the subnet, record then re-enter the default PID values to the first Unit Ventilator.

Procedure

Click the PID button on the left pane to open the PID Configuration page.
Enter information into available fields.
Click Commit to save the settings or Reset to revert to the last saved settings.
Click Next to display the Wiring Assignment page or Back to display the Miscellaneous Parameters Configuration page.

Equipment Damage Possible

Adjustments may cause large over or undershooting of setpoint. The default values provide proper control for most systems.

Fields

Name	Definition
Cooling Throttling Range	Throttling Range or Proportional Gain Determines what impact the error has on the output signal. Decreasing the Throttling Range amplifies the effect on the error, that is, for a given error (the difference between the measured space temperature and the current actual space temperature setpoint), a small Throttling Range causes a higher output signal value. Enter the range in degrees (2 deg. – 30 deg.F [-17 deg.C – -1 deg.C]).
Cooling Integral Time	Integral Time Determines what impact the error-over-time has on the output signal. Error-over-time has two components that make up its value: the amount of time the error exists and the size of the error. The higher the integral time, the slower the control response. In other words, a decrease in Integral Time causes a more rapid response in the output signal. Enter the range in seconds (0 – 5,000).
Cooling Derivative Time	Derivative Time or Gain Determines what impact the error rate has on the output signal. The error rate is how fast the error value is changing. It can also be the direction space temperature is going, either towards or away from the setpoint and its speed - quickly or slowly. A decrease in Derivative Time causes a given error rate to have a larger effect on the output signal. Enter the range in seconds (0 – 9,000).
Heating Throttling Range	Throttling Range or Proportional Gain Determines what impact the error has on the output signal. Decreasing the Throttling Range amplifies the effect on the error, that is, for a given error (the difference between the measured space temperature and the current actual space temperature setpoint), a small Throttling Range causes a higher output signal value. Enter the range in degrees (2 deg.F – 30 deg.F [-17 deg.C – -1 deg.C])
Heating Integral Time	Integral Time Determines what impact the error-over-time has on the output signal. Error-over-time has two components that make up its value: the amount of time the error exists and the size of the error. The higher the integral time, the slower the control response. In other words, a decrease in Integral Time causes a more rapid response in the output signal. Enter the range in seconds (0 – 5,000).
Heating Derivative Time	Derivative Time or Gain Determines what impact the error rate has on the output signal. The error rate is how fast the error value is changing. It can also be the direction space temperature is going, either towards or away from the setpoint and its speed - quickly or slowly. A decrease in Derivative Time causes a given error rate to have a larger effect on the output signal. Enter the range in seconds (0 – 9,000).

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