Applications Guide Tracer Graphical Programming - Trane

®
Contents
Chapter 5 Cooling tower with variable-speed fan example 79
Whatyouwilllearn..........................................79
Skills. . . . . . . ............................................79
Conceptsanddefinitions..................................79
Blocks..................................................79
Reviewingthesequenceofoperation...........................80
Condenser water pump . . . . . . . ............................80
Coolingtowerfan........................................80
Sumpheater............................................80
Alarms.................................................80
Calculations.............................................80
RefreshingtheTGPeditor ....................................84
Determiningaprogrammingapproach..........................84
Editingtheprogramproperties................................84
Modifying the alarms module . . . . . ............................85
Writing the calculations module . . . ............................86
Calculating change in water temperature across the cooling tower .
86
Calculatingtheambientwet-bulbtemperature................87
Calculatingtheapproachtemperature.......................87
Writing the cooling tower fan module. . . . . . . . . . . . ...............88
Startingandstoppingthefan ..............................88
Imposinglimits..........................................89
ImplementingPIDcontrol .................................91
SettingupthePIDblockproperties.......................91
IncorporatingthePIDblock.............................93
Writing the condenser water pump module . . . . . . . ...............94
Adding the input blocks . . . . . . . ............................95
Addingtheoutputblocks..................................95
Determiningwhentostartandstopthepump ................96
AddingaFeedbackAlarmblock .........................96
Checking conditions to start and stop the pump . . . . . . . . . . . . 98
Summaryquestions........................................104
Chapter 6 VAV AHU example . . ...................... 105
Whatyouwilllearn.........................................105
Skills. . . . . . . ...........................................105
Conceptsanddefinitions.................................105
Blocks.................................................105
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CNT-APG001-EN