Liebert NX UPS System Power Switches, UPS operating modes, Rotary switch configurations

Operating Procedures

6.0OPERATING PROCEDURES

! 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.

6.1Introduction

The NX can operate in any of four modes, as shown in Table 9. This section provides instructions on switching between modes, resetting the UPS, switching the inverter On and Off and performing other operations.

Table 9	UPS operating modes
		Rotary Switch
Operating Mode		Position	Description
Normal Operation		NORMAL	The UPS is powering the load.
		BYPASS or	The load power is supplied through the static bypass line. This may be
On Static Bypass			considered as a temporary mode during load transfers between inverter
		NORMAL
			and maintenance bypass or supply under abnormal operating conditions.
			No load power is supplied by the UPS. The load is connected to utility
On Test		TEST	power via the Maintenance Bypass Supply line. NOTE: The load is not
			protected against disturbances in AC input power in this mode.
On Maintenance			The UPS is shut down but the load is connected to utility power via the
		MAINT	Maintenance Bypass Supply line. NOTE: The load is not protected
Bypass
			against disturbances in AC input power in this mode.

NOTE

1. The user controls and indicators mentioned in these procedures are identified in 7.0 - Operator Control Panel and Display.

2.The audible alarm may sound at various points during these procedures. It can be canceled at any time by pressing the SILENCE ON/OFF push button.

NOTE

This unit refers to some modes and conditions that are set or adjusted using proprietary service software. To take advantage of all the available features for the NX, the unit must be commissioned by a Liebert factory-trained service engineer.

6.1.1Power Switches

The UPS unit power switches are CB1 and SW1.

•CB1-Input Current Breaker. Connects the utility supply to the UPS input.

•SW1 - Rotary switch. Has four positions—NORMAL, BYPASS, TEST and MAINT—that corre- spond to different positions of the SW1-A/B/C/D.

The positions of the rotary switch (SW1) are:

•SW1-A—Output Isolator. Connects the output of the UPS to the load.

•SW1-B—Neutral Isolator. Connects neutral to the UPS.

•SW1-C—Bypass Isolator. Connects the UPS with the bypass supply.

•SW1-D—Maintenance Bypass Isolator. Permits supply of the load directly by the bypass line for maintenance of the UPS unit.

The functions of the rotary switch are shown in Table 10.

Table 10 Rotary switch configurations

Rotary Switch	OUTPUT (SW1-A)	BYPASS (SW1-C)	MAINT	NEUTRAL (SW1-B)
Position			(SW1-D)
NORMAL	✔	✔		✔
BYPASS	✔	✔		✔
TEST		✔	✔	✔
MAINT			✔

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