Emerson SERIES 600T manual Open-Rack Batteries, Configuring Your Neutral and Ground Connections

6.3 Open-Rack Batteries

When batteries other than Liebert Battery Cabinets are used, a remote battery disconnect switch with overcurrent protection is required per the National Electrical Code. Refer to Figures 53 and 54. Contact your Liebert sales representative.

1.Install battery racks/cabinets and batteries per manufacturer's installation and maintenance instructions.

2.Verify battery area has adequate ventilation and battery operating temperature complies with manufacturer's specification.

3.Ensure that battery racks are properly grounded according to code requirements in your area.

If you have any questions concerning batteries, battery racks, or accessories, contact Liebert Global Services at 1-800-543-2378.

CAUTION

Cables between batteries and modules should be run in matched pairs, positive- with-negative. Grouping like-polarity cables together (i.e. positive-with-positive and negative-with-negative) can cause stress or damage to the cables, conduit or buswork.

7.CONFIGURING YOUR NEUTRAL AND GROUND CONNECTIONS

Improper grounding is the largest single cause of UPS installation and start-up problems. This is not an easy subject, since grounding techniques vary significantly from site to site, depending on several factors. The questions you should ask are:

•What is the configuration of the input power source? Most of the recommended schemes for UPS grounding require grounded-wye ser- vice. The UPS system requires a bypass neu- tral for sensing and monitoring the quality of the bypass input. If the building service is ungrounded delta or corner-grounded delta, contact your Liebert representative to ensure your system includes the Artificial Neutral or Isolated Neutral kit.

•Does the system have a bypass isolation transformer? Systems with 480 VAC (or 600 VAC) input and 208 VAC output require a bypass isolation transformer. In some cases, it may be necessary to treat that transformer as a “separately derived source” with its own grounding electrode. See page 10 for details.

•What are the UPS input and output voltages? Systems with 480 VAC input and output have significantly different needs than systems with 480/208 VAC or 208/208 VAC.

•What is the connected load? Does the critical load consist of one or more Power Distribu- tion Units (PDUs)? Do the PDUs have isola- tion transformers?

The following sections discuss recommended grounding procedures for various system configurations.

NOTE

Some UPS modules are equipped with input isolation transformers. However, these transformers have no effect upon any system grounding considerations. These modules will be grounded exactly as shown in the following examples.

Liebert Series 600T UPS, 65-225 kVA, Single Module 7

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