Damper Control

The DamperControl variable is used to directly control the motor which is responsible for opening or closing the damper. The motor is controlled in the form of a floating type of control, where a specific drive time is required for correct (full opening) control, allowing for full opening of the damper under load.

Due to the possibility of the transmitted signal diverging from the actual opening (e.g., in the event of jamming, blocking, etc.), a calibrated mechanism is used, which involves a calibration process for the duration of the motor's drive time. This function is always performed after the power supply voltage fails and returns, and cyclically, e.g. every day at midnight.

The priority signal is the damper operating mode resulting from, among others or testing procedure.

Damper control is carried out in the range defined by the MinDamperPosition and MaxDamperPosition variables, scaling the corresponding demands.

For the correct operation of the damper, the correct transition time for a full cycle—from fully closed to fully open—must be set in the DamperDriveTime variable (by default, 90 s) and the correct direction of damper operation must be set in the DirectionDirection variable as CW (clockwise) or CCW (counterclockwise).

The DamperPosition variable returns the actual value of the damper opening, and the DamperControl variable returns its control.

The Damper Command variable, accessible from the Control Point VAV panel and software like a iC Tool, iSMA Configurator or directly via BACnet/Modbus, is mainly used to force testing of the set damper position.

Damper Operating Modes

The damper can be configured to work in the following operating modes:

• Auto: the damper is controlled according to the pressure control loop output,

• Full Open: the damper control is forced to 100% open position,

• Full Close: the damper control is forced to 0% open position (closed), even when the MinDamperPosition value is higher than 0%,

• User Position: the damper control is forced to the user set position (the UserSetPosition variable),

• Min Flow: no action,

• Max Flow: no action,

• User Flow: no action,

• Calibrate: forces the damper calibration (the damper goes to 100%, then to 0%, and goes back to the control loop output).

Initial Position

The Initial Position function is an auto-synchronization of the actuator, which allows for maintaining proper airflow parameters. In the process, the damper goes to 0% and goes back to the control loop output. It is performed each first day of the month, on the time calculated by the formula:

Calibration time = 00:00 + (serial number MOD 100)

This way helps to avoid the situation when all controllers perform the process at one moment, compromising the stability of the system.

DamperResponse

In case of significant fluctuations of pressure demand (resulting from the respective control loop), it is possible to mitigate the changes of value using the DamperResponse variable. It allows to enforce the change of value on the DamperControl component if the change of output demand is higher than set in the DamperResponse In16 slot (by default, 2%). It means that the DamperControl output will change only if the pressure demand changes more than 2%.