Chapter 3 Parallel Ups Installation And Commissioning; Features; Requirements; Mechanical Installation - Emerson Liebert ITA 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) parallel configuration, N stands for the basic
parallel sets, X stands for the redundant sets.
1 + 1 parallel POD (optional) can provide safe and reliable power distribution function for the parallel system. The 1 +
1 parallel system only needs one 1 + 1 parallel POD; if N is not less than two, the external self-distribution will be
required for the parallel system.

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).
For all UPSs of the parallel system, the requirements of the parameter settings are same.
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 and must be connected to the same bypass source.
2. The bypass input power 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 or the
maintenance bypass 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.

3.3 Mechanical Installation

Taking the rack installation of the 1 + 1 parallel system without battery module for example, the mechanical
installation method of the parallel system is as follows:
1. The installation method of 1 + 1 parallel UPS is the same as that of the single UPS. Refer to 2.4 Mechanical
Installation for details.
2. As shown in Figure 3-1, the UPS should be installed at the bottom; and the 1 + 1 parallel POD should be installed
on the top to facilitate the cable connection and operation. The installation method of 1 + 1 parallel POD is the same
as that of the UPS.
Chapter 3 Parallel UPS Installation And Commissioning
Liebert ITA 16kVA And 20kVA UPS User Manual
®
27