AHU Supply Duct Static Pressure Control
Static pressure is controlled via a Variable Frequency Drive(VFD) at the supply air fan for a variable air volume system. The central monitoring panel displays sensors, actuators, charts, graphs, gauges, and status pilot lights. Also the system's PID controller can be tuned at the central monitoring panel.
Sequence Of Operation: This controls the AHU supply duct static pressure by modulating the fan speed via a variable frequency drive.

Current Value Chart: The measured static pressure(STP) strip chart is shown that records each minute the supply air duct static pressure and its setpoint during the previous 60 minutes.

Analog Gauges: Gauges are provided on the central monitoring panel that display: Supply duct static pressure(STP), fan motor frequency(Hz), fan motor voltage(VAC), and the controller output(CO) value to the VFD.

System Chart: Select the button to view the static pressure system strip chart that each minute it records the STP, Hz, VAC, and CO gauge values during the previous 100 minutes.

Controller Status: A 5-state status pilot light is included for the local controller, shown inside this controller's diagram.

PID Controller: The central monitoring panel can tune the PID loop. It displays and has access to adjust the following values associated with the controller:
1.) Static Pressure Setpoint(SP) - When this radio button is checked it the static pressure setpoint is available for change.
2.) Proportional(P) Value - When this radio button is checked the value is available for change.
3.) Intergral(I) Value (repeats/minute) - When the checkbox is un-checked the integral is is ignored. When the radio button is checked the value is available for change.
4.) Derivative(D) Value - When the checkbox is un-checked the derivative value is ignored. When the radio button is checked the value is available for change.
5.) VFD Demand(CO): 0 to 100% - When this radio button is checked it overrides the controller output (CO) and selects a manual mode.

Choose the radio button for desired value to adjust. Select the increment, then use the or button to change value.

VFD Status: A 5-state status pilot light monitors the VFD status: minimum operating frequency (ON), maximum operating frequency (NORMAL OFF), or modulating (INTERMITTENT), and disabled/repairing (DEFECTIVE). If the VFD's local circuit detects a fault, the status will show ALARM.
VFD STP Supply Fan Variable Air Volume
Tune Controller:
SP: P: I: D: CO:
     
Supply Duct Static Pressure STP (in. W.C.) Minutes VFD

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