Tandem Compressors; Tandem Digital Scroll Assignment; Figure 24 Liebert Dse Refrigeration Circuit Overview - Emerson Liebert iCOM Manual

3.3

Tandem Compressors

Liebert digital tandem compressors will modulate the digital and fixed compressors to satisfy the
temperature setpoint. Both digital tandem compressor sets work together to provide cooling and
limiting moisture removal by utilizing both circuits. One of the two compressors is a digital
compressor and the other is a fixed-capacity standard scroll compressor.
In the digital tandem set, Circuit 1 makes up the outer coil and has two compressors connected to the
circuit. Circuit 2 has the same components, but is positioned as the lower, or second, coil. Each
compressor circuit is referred as a Tandem Digital Scroll Compressor set.

Figure 24 Liebert DSE refrigeration circuit overview

Tandem Compressor 1
System 1
3.3.1

Tandem Digital Scroll Assignment

When referring to Tandem Digital Scroll Compressors, the following naming conventions are used:
• The terms Compressor 1A, Compressor 1B, Compressor 2A and Compressor 2B describe specific
compressors within the Liebert iCOM software.
• Tandem Digital Scroll Compressor Set 1 is composed of Compressor 1A and Compressor 1B.
Compressor 1A is a digital scroll compressor, and Compressor 1B is a fixed-capacity compressor,
which will often be referred to simply as a "fixed" compressor. The same rules apply to Tandem
Bank 2.
• The activation and deactivation of compressors may also be expressed as Cooling Stages, where
each stage is defined by which compressor is active. Cooling Stage 1 occurs when the first
compressor in the sequence comes On. Cooling Stage 4 occurs when all four compressors in the
unit are On.
Stage 1 1 Digital Compressor (C1A)
Stage 2 2 Digital Compressors (C1A + C2A)
2 Digital Compressors and 1 Fixed Compressor
Stage 3
(C1A + C2A + C1B)
2 Digital Compressors and 2 Fixed Compressors
Stage 4
(C1A + C2A + C2A + C2B)
® ®
Liebert iCOM for Liebert DSE
EEV
Condenser 1
™
Tandem Compressor 2
EEV
Condenser 2
Stage 1 Range of Unit's Rated Capacity
(10% to 25%)
Stage 2 Range of Unit's Rated Capacity
(20% to 50%)
Stage 3 Range of Unit's Rated Capacity
(45% to 75%)
Stage 4 Range of Unit's Rated Capacity
(70% to 100%)
30
Operation
System 2