Chapter 3 Parallel Ups Installation And Commissioning; Features; Requirements - Liebert S600 User Manual

Chapter 3 Parallel UPS Installation and Commissioning

This chapter introduces the features, requirements, installation and commissioning of the parallel system.
The UPS parallel system provides the user with N + X (2 ≤ N + X ≤ 4, X=0 or 1) parallel configuration, N stands for
the basic parallel sets, X stands for the redundant sets.

3.1 Features

1. The software and the hardware of each UPS in parallel system are the same as those of the single UPS. The basic
parameters of the parallel system can be set through the LCD (Refer to 3.5.2 Parallel System Parameters Setting for
details), and the detailed parameters can be set through the background software (For service engineers only).
2. The parallel cables form a ring connection (Refer to 3.4.2 Connecting Parallel Cables for details) to provide
reliability and redundancy for the system. The intelligent parallel logic provides the user with maximum flexibility. For
example, each UPS in the parallel system can be switched off or on in random order; seamless transfer can be achieved
between Normal mode and Bypass mode, and the transfer is automatically recoverable: that is, after the overload is
removed, the system will return to the original operation mode automatically.
3. The total load of the parallel system can be queried through the LCD of each UPS.

3.2 Requirements

A UPS system composed of multiple parallel-connected UPSs is equivalent to a large UPS system. Nevertheless, it
provides increased system reliability. To ensure equal utilization of all UPSs and compliance with relevant wiring
regulations, the following requirements must be met:
1. All single UPSs must have the same capacity. The 10kVA//20kVA UPS must be connected to the same bypass
source.
2. The bypass input power (10kVA/20kVA only) and the rectifier input power must be connected to the same neutral
line input terminal.
3. If a residual current detector (RCD) is required, it must be set correctly and installed before the same neutral line
input terminal, or it must monitor the protective earth current of the system. Refer to 'Warning: high leakage current' of
Safety Precautions before Contents.
4. The outputs of all single UPSs must be connected to the same output bus.
5. Because the UPS parallel system is not fitted with any auxiliary contact detection devices for the output MCB of the
UPS, removing the single UPS from the parallel system before maintenance and adding the single UPS into the
parallel system after maintenance must be conducted strictly following the procedures provided in 5.2 Transfer
Procedures Between Operation Modes. Failure to observe this may affect the reliability of the load power supply.
Vertiv|Liebert® S600 10kVA ~ 20kVA UPS | User Manual 26