4.2 The Parameters of the Control System Building Management System (BMS) is a stand-alone computer system that monitors, controls and optimises the operation of the facilities and systems in the building. This allows the building to have good control of the internal conditions, increased comfort levels for occupants, effective monitoring of energy consumption, and saves time and money during overall maintenance.
A BMS normally consists of many systems, such as lighting, HVAC, security system, fire alarm. Variable Refrigerant Flow Air (VRF) is used for cooling and Variable Air Volume system (VAV) is for ventilation purpose.
In a control system, there are three basic elements: a sensor, controller, and a controlled device. Figure 19 shows an example of how control system works and the components involved. First, the sensor measures a variable such as the temperature in a room, and the values are transmitted to the controller through the signal conditioner and a transmitter. Then the controller takes the values into account and alters the output signal to the controlled device through the actuator. An actuator provides the mechanical action to operate the final control device, which is typically a valve or damper. Finally, the device will change the output of the load based on the signal received from the controller. Depending on what variables are required to be controlled, the components, such as sensors and the controlled devices, will differ in each control system.
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