Applications Guide Tracer Graphical Programming - Trane

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Chapter 4 Cooling tower with two-speed fan example
Figure 80: Deadbands used to control fan speed
Use a Math block to incorporate this functionality. Math blocks perform
standard math operations and functions. Specifically, use an Add block to
adjust the setpoint value by adding 5.0°F. The result of the addition
serves as the setpoint input to the Deadband block.
To transition the fan based on supply temp:
1. Place a Deadband block in the design space and set it as Greater
Than.
2. From the Blocks menu, choose Math. From the Math menu, choose
Add.
3. Click in the design space to place an Add block.
4. Place a Constant block in the design space and assign the value 5.0 to
it.
5. Connect the SupplyTemp wireless read block to the Input port of the
Deadband block.
6. Connect the Supply Temp Setpoint variable block and the 5.0 constant
block to the Add block.
7. Connect the Add block to the Setpoint port of the Deadband block.
8. Place a Constant block in the design space and assign the value 2.5 to
it.
9. Connect the 2.5 constant block to the Deadband port of the Deadband
block (Figure 81 on page 75).
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