Liebert TM-10098 service manual 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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