Parallel System Features; Requirements For Paralleling Of Ups Modules; Operation Mode - Liebert APM 150 User Manual

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Input mains supply
L1, L2, L3, N
L1, L2, L3, N

1.3.1 Parallel System Features

1. The hardware and software of parallel system are completely the same as those of single UPS module. The
parallel configuration is achieved through settings in configuration software. The parameter settings of each
UPS module in parallel system should be the same.
2. Parallel cables are connected in a ring, providing both system reliability and redundancy. Dual bus control
cables are connected between any two UPS modules of each bus. The intelligent parallel logic provides the
user with maximum flexibility. For example, shutting down or starting up UPS modules in a parallel system can
be done in any sequence. Transfers between normal and bypass modes of operation are synchronized and
self-recoverable, for example, following overloads and their clearance.
3. The total load of the parallel system can be queried from each UPS module's LCD.

1.3.2 Requirements For Paralleling Of UPS Modules

A UPS system consisting of two paralleled UPS modules behave as if it were one large UPS with the advantage
of presenting higher reliability. To ensure that all modules are equally used and to comply with relevant wiring
rules, the following requirements apply:
1. All UPS modules must be of the same rating and must be connected to the same source.
2. Any RCD, if installed, must be of an appropriate setting and located upstream of the common neutral
bonding point. Alternatively, the device must monitor the protective earth current of the system. Refer to
Warning: high leakage current before Contents.
3. The outputs of the two UPS modules must be connected to a common output bus.

1.4 Operation Mode

The UPS is an on-line, double-conversion, reverse-transfer UPS that permits operation in these modes:
Normal mode

Battery mode

Liebert APM 150 Integrated UPS Single Module And Parallel System
Qin UPS 1
Rectifier
Charger
STS
Inverter
Qout UPS 1
UPS 1 output
L1, L2, L3
N
UPS 1 output distribution
unit 0~2 pcs
UPS 1 output distribution
Input mains supply
L1, L2, L3, N
Figure 1-3 Parallel system
Chapter 1 Overview
Qin UPS 2
Rectifier
Charger
STS
Inverter
Qout UPS 2
L1, L2, L3, N UPS 2 output
L1, L2, L3 N
UPS 2 output distribution
unit 0~2 pcs
UPS 2 output distribution
User Manual
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