4 Stage Compressorized Cooling – No Dead Band

iCOM Control Training and Service Manual

4 Stage Compressorized Cooling – No Dead Band

Temp Set Point + (1/2 Proportional Band)

 

Temp Set Point: 70°F

 

 

 

 

 

Proportional Band: 8°F

 

 

 

Cool 4 On

 

 

Cool 2 On

 

 

 

Cool 1 On

 

Cool 3 On

 

 

70

71

72

 

73

74

75

 

Cool 2 Off

 

Cool 4 Off

 

Cool 1 Off

Cool 3

Off

 

 

 

 

 

 

 

Increasing Temperature

Note: in the above example that the control band begins at the 70°F temperature set point and has a length of 4°F, which is ½ of the programmed temperature proportional band value.

As the return air temperature increases Cooling 1, the lead compressor unloaded, is activated at 71°F or 25% of the cooling control band. If the return air temperature continues to increase Cooling 2, the lag compressor unloaded is activated at 72°F or 50% of the cooling control band. If the return air temperature continues to increase Cooling 3, the lead compressor is loaded at 73°F or 75% of the cooling control band. If the return air temperature continues to increase Cooling 4, the lag compressor is loaded at 74°F or 100% of the cooling control band.

When the return air temperature starts to decrease, Cooling 4 is deactivated at

73°F or 75% of the cooling control band. If the return air temperature continues to decrease Cooling 3 is deactivate at 72°F or 50% of the cooling control band. If the return air temperature continues to decrease Cooling 2 is deactivate at 71°F or 25% of the cooling control band and Cooling 1 is deactivated at the temperature set point of 70°F or 0% of the cooling control band.

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Liebert TM-10098 service manual Stage Compressorized Cooling – No Dead Band, Temp Set Point + 1/2 Proportional Band