HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Energy and Power Management, Distributed Control Trendsin the control system. In a simple controller chip, Firmware may containthe Operating System (OS). It could also include communication protocols,data libraries and special parameters.The OS provides the basic requirements for computing. It managesall input and output functions necessary for computing. A hierarchicalstructure of functions is normally used to manage the flow of informationand control the activity throughout the processor.In the past, controller manufacturers would develop proprietaryoperating systems and communication protocols. This meant there wereno standards for communication.Using a standard chip set for both operating system and communicationis being done for bus standards such as Lonworks from Echelon.Lonworks provides a complete set of system tools.Another trend is the use of Microsoft Windows as the basis for PCinterface software. This gives everyone using the system access to compatiblesoftware and offers many tools to improve productivity.Application specific device parameters might include informationsuch as the number of stages of cooling in an air handler. These parametersare dynamic and allow the system to be fine tuned to the controlapplication.Data TrendingThis involves collecting information over some time period forHVAC applications. This information makes it possible to analyzeequipment operations and can be used to fine tune control sequencesand identify mechanical problems. Trending provides the data needed toincrease the effectiveness of HVAC control.SetpointsSetpoints are more dynamic than parameters since they may bechanged on a day to day basis. Setpoints define the control conditionsthat are to be maintained for a given application. The changing of setpointsoftware files may be done from a central interface, hand-heldterminal or even a zone sensor. Some zone sensors use a thumblewheelpotentiometer or digital readout to allow a setpoint change.©2001 by The Fairmont Press, Inc. All rights reserved.