Dual Bus System; Cabinet Installation; External Protective Device; Power Cable - Emerson NXr User Manual

26 Chapter 3 Installation Of Parallel System
J2
J3
J4

3.3 Dual Bus System

3.3.1 Cabinet Installation

A dual bus system consists of two independent UPS systems, each containing one or more (maximally 4) parallel
UPS modules, as shown in Figure 3-7. The dual bus system has high reliability and is suitable for load with multiple
input terminals. For single-input load, an optional static transfer switch can be fitted to start the load bus synchronizer
(LBS supplied in standard configuration.
Main input
The dual bus system uses the LBS to keep the output of the two independent UPS systems (or parallel systems) in
synchronization. One system is designated as the master, the other is designated as the slave. The operation modes
of the parallel system comprise master and/or slave operation in normal or bypass mode.
Place the UPS modules side by side and interconnect the UPS modules according to the following instructions.

3.3.2 External protective device

Refer to Chapter 1 Installation Of single UPS cubicle .

3.3.3 Power Cable

The wiring of power cables is similar to that of single module system. The bypass and the main input sources must be
referenced to the same neutral potential and input earth leakage monitoring devices, if installed, must be located
upstream of the common neutral sinking point. Refer to Chapter 1 Installation Of single UPS cubicle .

3.3.4 Control Cable

For NXr-to-NXr dual bus system, connect the optional LBS cables between the LBS ports (J4) of the two parallel
systems, as shown in Figure 3-8. The LBS port (J4) is provided on the front panel of the bypass module, as shown in
Figure 3-6.
NXr UPS Module And Parallel System 30kVA ~ 200kVA User Manual
Figure 3-6 Locations of ports J2, J3 and J4 on bypass module
Bypass
UPS 1 Main input
UPS4
Parallel
control
cable
Figure 3-7 Typical dual bus system (with static transfer switch and LBS)
Main input
LBS
STS
To load
Bypass
UPS 1 Main input
UPS4
Parallel
control
cable