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

Energy and Power Management, Distributed Control Trendsa variety of reports can be obtained quickly. Audit trails also go morequickly and can be used to substantiate proof of performance, as well aslimit future risk. A networked control system can automatically documentprocesses, generate reports and issue work orders when problemsare detected at a point in the network.Levels of ControlNetworked control systems generally use several levels of hierarchyin their distributed architecture. Three levels that can be used are:• distributed controllers,• building-wide control and• information management.Each level serves its own purpose, but all levels are interconnected,similar to the operating structure of a corporation.Distributed controllers may employ microprocessor-based sensorsand other devices to meet the needs of a specific application. Thesestand-alone controllers or control systems function as specialized toolsfor a specific job.The building-wide level coordinates all of the building controlstrategies. This level coordinates the specialized activities and providesglobal direction.At the information management level, data collected from variouspoints in the system are transformed into usable information. The combinedefforts of the highly specialized field units the higher levels ofcontrol to provide and in some cases make information decisions aboutthe operations of the overall system.Distributed HVAC ControlDistributed control refers to a complete control system with all theneeded inputs, output and control processing logic to affect a controlloop. In HVAC the controlled parameters include standard functionssuch as discharge air temperature, space temperature, humidity and fancontrol.©2001 by The Fairmont Press, Inc. All rights reserved.