2 Stage Compressorized Cooling – With Dead Band - Emerson Liebert iCOM Training And Service Manual

iCOM
Controls Training and Service Manual
In the example below the control band begins at the 70°F temperature set point
and has a length of 4.5°F, which is ½ of the programmed temperature dead band
value plus ½ of the programmed temperature proportional band value.
As the return air temperature increases, Cooling 1 (lead compressor) is activated
at 72.5°F or ½ of the dead band value plus 50% of the cooling control band. If the
return air temperature continues to increase, Cooling 2 (lag compressor) will
activate at 74.5°F or ½ of the dead band value plus 100% of the cooling control
band.
When the return air temperature starts to decrease, Cooling 2 (lag compressor) is
deactivated at 72.5°F or ½ of the dead band value plus 50% of the cooling control
band and Cooling 1 (lead compressor) is deactivated at 70.5°F or ½ of the dead
band value plus 0% of the cooling control band.
2 Stage Compressorized Cooling – With Dead Band
Remember the temperature dead band value is used by the control to shift
the cooling on/off operations away from the temperature set point.
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