Liebert NX UPS System user manual Split-Bypass Input

Operation

5.0 OPERATION

! WARNING

Hazardous Mains and / or Battery Voltage present behind covers.

No user-serviceable parts are located behind covers that require a tool for their removal. Only qualified service personnel are authorised to remove such covers.

5.1Introduction

Liebert’s NX™ Uninterruptible Power System system provides continuous, high-quality AC power to your business-critical equipment, such as telecommunications and data processing equipment. The NX UPS supplies power that is free of the disturbances and variations in voltage and frequency com- mon to utility power, which is subject to brownouts, blackouts, surges and sags.

The NX utilizes the latest in high frequency, double-conversion pulse width modulation (PWM) tech- nology and fully digital controls to enhance its reliability and increase the ease of use.

The standard NX consists of the UPS and internal batteries in a compact, single cabinet.

As shown in Figure 27, the AC utility source is input at CB1 and the rectifier converts the AC utility into DC power. The inverter converts that DC power from the utility—or DC power from the batteries —into AC power for the load. The batteries power the load through the inverter in the event of a power failure. The utility source can also power the load through the static bypass.

If maintenance or repair of the UPS is necessary, the load can be switched without interruption in service to the maintenance bypass.

Figure 27 Single unit block diagram with split-bypass input

	SW1/D			Maintenance Bypass
Bypass	SW1/C			Static Swich
Input				UPS
				Output
AC Utility				SW1/A
Input
	CB1			Static Swich
	Rectifier	Discharge	Inverter
				SW1/B
Neutral
			Battery
Wire
			Charger
				Neutral
				Wire
	Battery

5.1.1Split-Bypass Input

Figure 27 illustrates the Liebert NX UPS in what is known as the split-bypassconfiguration wherein a separate power switch to a dedicated bypass power source that also feeds the maintenance bypass line connects the static bypass line. Where a separate power source is not available, the bypass and rectifier input supply connections are linked.

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