Applications Guide Tracer Graphical Programming - Trane
Applications Guide Tracer Graphical Programming - Trane Applications Guide Tracer Graphical Programming - Trane
® Chapter 5 Cooling tower with variable-speed fan example To calculate the approach temperature: 1. Place a Subtract block in the design space and connect it so that the Wet-Bulb Temp is subtracted from the Supply Temp. 2. Place a Variable block in the design space and assign the analog variable, Approach Temp, to it. 3. Connect the Subtract block to the Approach Temp variable block so that the calculated value is written to the variable (Figure 89). Figure 89: Calculations module complete Writing the cooling tower fan module The new sequence of operation calls for modulation of the fan speed to maintain the condenser water supply temperature. Upon successful confirmation of condenser water flow, and when the cooling tower water supply temperature exceeds the setpoint by 2.5°F, turn on the fan. Modulate the fan to maintain the condenser water supply temperature according to setpoint. When the cooling tower supply water temperature is 2.5°F below the setpoint, turn off the fan. Note that the setpoint is adjustable from the operator display and is limited to a minimum of 65°F and a maximum of 95°F. Starting and stopping the fan As in Chapter 4, a deadband is required to start and stop the fan. Use a centered deadband to start the fan when the water temperature is 2.5°F above the setpoint and to stop the fan when the water temperature is 2.5°F below setpoint. Remember that flow must be confirmed in order for the fan to start. 88 CNT-APG001-EN
® Writing the cooling tower fan module Figure 90: Previous cooling tower fan module To start and stop the fan: 1. Return to the cooling tower fan module of your program (Figure 90). Figure 91: Using a deadband to start and stop the fan 2. Delete all the blocks implementing the transition of the fan to high speed (Figure 91). Imposing limits The program must check the setpoint against the setpoint limits per the sequence of operation. You have two options as to which blocks to use. The limit may be applied using a combination of the Min and Max blocks, or you may use the Limit block. Figure 92 on page 90 is an example of how you could use the Min and Max blocks. CNT-APG001-EN 89
- Page 62 and 63: ® Chapter 3 Modifying the exhaust
- Page 64 and 65: ® Chapter 3 Modifying the exhaust
- Page 66 and 67: ® Chapter 3 Modifying the exhaust
- Page 68 and 69: ® Chapter 3 Modifying the exhaust
- Page 70 and 71: ® Chapter 3 Modifying the exhaust
- Page 72 and 73: ® Chapter 4 Cooling tower with two
- Page 74 and 75: ® Chapter 4 Cooling tower with two
- Page 76 and 77: ® Chapter 4 Cooling tower with two
- Page 78 and 79: ® Chapter 4 Cooling tower with two
- Page 80 and 81: ® Chapter 4 Cooling tower with two
- Page 82 and 83: ® Chapter 4 Cooling tower with two
- Page 84 and 85: ® Chapter 4 Cooling tower with two
- Page 86 and 87: ® Chapter 4 Cooling tower with two
- Page 88 and 89: ® Chapter 4 Cooling tower with two
- Page 90 and 91: ® Chapter 4 Cooling tower with two
- Page 92 and 93: ® Chapter 4 Cooling tower with two
- Page 94 and 95: ® Chapter 4 Cooling tower with two
- Page 96 and 97: ® Chapter 4 Cooling tower with two
- Page 98 and 99: ® Chapter 4 Cooling tower with two
- Page 100 and 101: ® Chapter 4 Cooling tower with two
- Page 102 and 103: ® Chapter 4 Cooling tower with two
- Page 104 and 105: ® Chapter 5 Cooling tower with var
- Page 106 and 107: ® Chapter 5 Cooling tower with var
- Page 108 and 109: ® Chapter 5 Cooling tower with var
- Page 110 and 111: ® Chapter 5 Cooling tower with var
- Page 114 and 115: ® Chapter 5 Cooling tower with var
- Page 116 and 117: ® Chapter 5 Cooling tower with var
- Page 118 and 119: ® Chapter 5 Cooling tower with var
- Page 120 and 121: ® Chapter 5 Cooling tower with var
- Page 122 and 123: ® Chapter 5 Cooling tower with var
- Page 124 and 125: ® Chapter 5 Cooling tower with var
- Page 126 and 127: ® Chapter 5 Cooling tower with var
- Page 128 and 129: ® Chapter 5 Cooling tower with var
- Page 130 and 131: ® Chapter 6 VAV AHU example Review
- Page 132 and 133: ® Chapter 6 VAV AHU example contro
- Page 134 and 135: ® Chapter 6 VAV AHU example Table
- Page 136 and 137: ® Chapter 6 VAV AHU example Figure
- Page 138 and 139: ® Chapter 6 VAV AHU example Figure
- Page 140 and 141: ® Chapter 6 VAV AHU example Figure
- Page 142 and 143: ® Chapter 6 VAV AHU example Figure
- Page 144 and 145: ® Chapter 6 VAV AHU example Figure
- Page 146 and 147: ® Chapter 6 VAV AHU example Figure
- Page 148 and 149: ® Chapter 6 VAV AHU example Figure
- Page 150 and 151: ® Chapter 6 VAV AHU example Figure
- Page 152 and 153: ® Chapter 6 VAV AHU example Writin
- Page 154 and 155: ® Chapter 6 VAV AHU example Indica
- Page 156 and 157: ® Chapter 6 VAV AHU example Figure
- Page 158 and 159: ® Chapter 6 VAV AHU example Alarm
- Page 160 and 161: ® Chapter 6 VAV AHU example charge
®<br />
Writing the cooling tower fan module<br />
Figure 90: Previous cooling tower fan module<br />
To start and stop the fan:<br />
1. Return to the cooling tower fan module of your program (Figure 90).<br />
Figure 91: Using a deadband to start and stop the fan<br />
2. Delete all the blocks implementing the transition of the fan to high<br />
speed (Figure 91).<br />
Imposing limits<br />
The program must check the setpoint against the setpoint limits per the<br />
sequence of operation. You have two options as to which blocks to use. The<br />
limit may be applied using a combination of the Min and Max blocks, or<br />
you may use the Limit block. Figure 92 on page 90 is an example of how<br />
you could use the Min and Max blocks.<br />
CNT-APG001-EN 89
Change language