Liebert NX UPS System user manual Dual Bus System

UPS Multi-Module Installation

3.4Dual Bus System

3.4.1Cabinet Installation

The Dual Bus System consists of two independent UPS configurations each consisting of one or more UPS modules. Dual Bus Systems are high availability configurations suitable for loads with multiple input terminals. For single input loads an optional Static Transfer Switch may be added and the stan- dard Load Bus Synchroniser activated. Depending on the configuration, follow the appropriate instal- lation instructions for each system.

Place the UPS modules side by side and interconnect as shown below.

The objective of the Dual-bus Synchronizer (DBS) is to keep the output of two independent UPS sys- tems (or parallel systems) in synchronization. One system is designated as the master; the other is designated as the slave. The operating modes covered comprise master and or slave operating inverter or bypass mode.

Figure 18 Typical dual bus system configuration with static transfer switch and Load Bus Synch

Bypass	Bypass
supply	supply

	Input		Input
Rectifier			Rectifier
	UPS1	UPS 6

Input

Rectifier

		Input
UPS1		Rectifier
	UPS 6

Intermodule control cable

LBS

STS

Intermodule control cable

Load

3.4.2External Protective Devices

Refer to the instructions supplied in 1.0 - Single Module UPS Installation.

3.4.3Power Cables

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 the instructions in 1.0 - Single Module UPS Installation

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