Emerson Liebert iCOM Manual De Usuario

Two Compressors With Unloaders—Four-Step
The first two-step compressor is started unloaded at 33% calculated output from the temperature 

proportional band and stopped at 17%. At 80%, Compressor 1 will be loaded, at 70% unloaded. 
The second compressor starts unloaded at 63% and stops at 47%. At 100%, Compressor 2 will be 

loaded, at 90% unloaded (see Figure 28).
The four stages of cooling are accomplished in the following manner:

• 1 stage: One compressor, unloaded - Cool 1
• 2 stages: Both compressors, unloaded - Cool 2
• 3 stages: One compressor, loaded and one compressor, unloaded - Cool 3
• 4 stages: Both compressors, loaded - Cool 4