Liebert UPS System - Manual (Page 94)

Chapter 8 Parallel System
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UPS in the system, and operation condition of each unit can be monitored through
the remote computer.
8.1.2 Theory of Operation
1. Parallel System consisting of two units
This is the most frequently used configuration and its operation theory is shown in
Figure 8-1
Fig. 8-1 UPS parallel operation mode(two UPS modules)
2. Paralleling for Redundancy of more than two units
(N+X) system : N number of UPS is supporting the load and X number of UPS are
redundant. If the rating of each UPS unit is Po and the total load capacity is Pmax,
then (N-1) x Po < Pmax < N x Po, as shown in Figure 8-2