Case study of an HVAC control system for a server farm cooled by oil immersion. One Industrial Shields M-Duino Ethernet PLC Arduino 19R+ runs three control loops: a PID loop on the oil temperature of the tank, whose output sets the flow the cooler delivers over a serial link; ON/OFF control of the humidifier, dehumidifier and air conditioning from the room temperature and humidity sensors; and variable speed ventilation through a frequency drive with a 0-10 V analog reference that follows the odor level.

The PDF covers the challenge, the three control loops, the system architecture with the full signal list and the hardware used. Interactive version: HVAC case study online.