Watlow F4T

Watlow F4T • 78 • Chapter 4 Application Examples
Application Tips:
• The special output block is initially located in the library and can be dragged to the
canvas.
• The signals from the temperature and humidity loops’ PWR transmitters to A and B on
the special output block indicate the percent output power for each of the loops which
allow it to determine when the temperature and/or humidity loops need or may soon
need the compressor to be on.
• The signal from OUT on the special output block signals when to turn on the compres-
sor.
• Enter names for blocks where possible to make the application easier to understand.
• Set the special output’s function parameter to Compressor Control.
• Set the Minimum On Time and Minimum Off Time parameters long enough to protect
the compressor from too much cycling, but short enough to allow the compressor to
turn off between uses, for example 45 seconds for minimum on time and 15 seconds for
minimum off time.
• Set Input A Turn On and Input B Turn On to the percent of power from the tempera-
ture and humidity loops at which you want the compressor to turn on so that it is ready
when the loop needs cooling or dehumidification, for example 0%.
• Set Input A Turn Off and Input B Turn Off to the percent power at which you would be
comfortable having the compressor turn off, for example 2% for temperature and 5% for
humidity.
• Note the correct settings for the parameters above depend on the specific application
hardware.
• For more information on compressor control parameters see the section entitled "Com-
pressor Control" in Chapter 5.