2.3 Parallel System
Up to 4 UPS units can be parallelly connected to form a parallel system to increase the system capacity and reliability. The
load is equally shared between the paralleled UPS modules.
Moreover, 2 UPS units or parallel system can comprise a dual bus system. Each parallel system has independent output.
Output synchronization is achieved through the LBS cable or LBS adapter, enabling seamless load transfer between the 2
parallel systems or single units through the STS device.
2.3.1 Parallel system features
1. The hardware and software of parallel system are completely the same as those of the single module. The
parallel system configuration is achieved through settings in configuration software.
2. Parallel cables are connected in a ring, providing both system reliability and redundancy.
3. The total load of the parallel system is identified from the touchscreen of each UPS module.
2.3.2 Parallel system requirements
A group of parallel modules operate as if it is one large UPS with higher reliability. To ensure that all modules are equally
utilized and to comply with relevant wiring rules, make sure that the following requirements are met.
1. All UPS modules must be in the same model, and connect to the same bypass source.
2. The bypass and rectifier input sources must be connected to the same neutral line input terminal.
3. Any RCD, if installed, must be of an appropriate setting and located upstream of the common neutral line input
terminal. Alternatively, the device must monitor the protective earth current of the system.
WARNING! High earth leakage current in safety precaution. Earth connection is essential before connecting
input power (including power supply and battery).
2.4 Operation Modes
The UPS has the following operation modes:
• Normal mode
• Battery mode
• Automatic restart mode
• Bypass mode
• Maintenance mode
• ECO mode
• Parallel redundancy mode
• LBS mode
• Dynamic online mode
Normal mode
As shown in Figure 2.7 on the facing page, the mains is rectified by the UPS rectifier and inverted by the inverter to supply
uninterrupted AC power to the loads. At the same time, the charger will charge the battery.
14 Proprietary and Confidential ©2023 Vertiv Group Corp. 2 Overview
Vertiv™ Liebert® APM2 30 to 120 kVA Modular UPS User Manual
To Next Page
Loading...
