Emerson 610 installation manual Alternate Grounding Configuration, Wye-Connected Service

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Configuring Your Neutral and Ground Connections

6.2Alternate Grounding Configuration, Wye-Connected Service

This configuration must NOT be used when single-phase loads are directly connected to the UPS.

The alternate configuration is similar to that shown in 6.1 - Preferred Grounding Configuration, Wye-Connected Service, except that the service entrance neutral is not brought into the UPS mod- ule. In this configuration, the UPS output transformer is considered a separately derived source. The UPS module neutral is bonded to the UPS ground, which is connected to a local grounding electrode in accordance with NEC 250-26.

Please note that this configuration represents a price/performance trade-off. Whenever the UPS mod- ule transfers to or from bypass, two AC sources (input and bypass) are briefly connected together and circulating current must flow. In the previous configuration, the current flows through the neutral conductor. In this configuration, the current flows through the ground path, possibly tripping ground fault interrupters (GFIs) and distorting the bypass waveform reference.

Proper adjustment of ground fault interrupters is necessary to avoid unwanted tripping.

Figure 5 Alternate grounding configuration, wye-connected service

This configuration is reserved for applications that meet all the following criteria:

• The facility has wye-connected service.

• The module rectifier input and bypass input are fed from the same source.

• The connected load is strictly 3-wire (such as one or more PDUs) and does not require a neu- tral from the UPS.

• Special precautions are taken to prevent tripping the ground fault interrupters. The time delay should be set to at least 0.2 seconds to prevent tripping when the UPS performs a trans- fer or retransfer operation.

! CAUTION

Failure to properly set the ground fault interrupters could cause loss of power to the critical load.

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Contents Liebert Series 610 UPS Contacting Liebert for Support Battery Cabinet PrecautionsTable of Contents Figures Iii Tables Important Safety Instructions Page Installation Considerations Multi-Module 500 to 750kVA UPS System Control Cabinets Types of System Control CabinetsUnloading and Handling External Inspections Internal Inspections and Shipping Material RemovalInspections Equipment Location Battery Installation Battery Safety PrecautionsAvertissement Battery Safety Precautions in French Per CSA RequirementsBattery Cabinets Open-Rack Batteries Configuring Your Neutral and Ground Connections Preferred grounding configuration, wye-connected service Preferred Grounding Configuration, Wye-Connected ServiceAlternate grounding configuration, wye-connected service Alternate Grounding Configuration, Wye-Connected ServicePreferred grounding configuration with isolated bypass Preferred Grounding Configuration With Isolated BypassAlternate grounding configuration, non-isolated Alternate Grounding Configuration, Non-IsolatedConfiguring Your Neutral and Ground Connections Preferred grounding configuration, impedance-grounded wye Preferred grounding configuration, battery systems Preferred Grounding Configuration, Battery SystemsWiring Considerations Power Wiring Scct Abbreviations for circuit breakers Control WiringBattery Wiring Specific Connections Wiring ConnectionsWiring Connections Power wiring terminals, factory supplied Wiring InspectionField-supplied lugs 16, National Electrical Code Reprint Installation Drawings 97-797600-176 Rev 88-797658-84 Rev 88-797658-94 Rev 88-797657-26 Rev 88-797657-95 Rev Outline drawing, 500kVA Multi-Module UPS, 12-pulse rectifier 88-797657-92 Rev 88-797668-84 Rev 88-797668-90 Rev 88-797665-29 Rev 88-797665-90 Rev 88-797656-66 Rev 88-797656-86 Rev 88-797668-66 Rev 88-797668-86 Rev 88-797664-68 Rev 88-797664-88 Rev 88-797677-65 Rev Base mounting patterns, 500kVA module, 6-pulse rectifier Base mounting patterns, 500kVA module, 12-pulse rectifier 88-797613-28 Rev Base mounting patterns, 625-750kVA module, 6-pulse rectifier 88-797613-29 Rev 88-797613-19 Rev 88-797613-27 Rev Shipping split detail, 500kVA, 12-pulse rectifier 88-797612-08 Rev Shipping split detail, 625-750kVA, 6-pulse rectifier 88-797612-09 Rev Shipping split detail, 625-750kVA, 12-pulse rectifier 88-797612-07 Rev Battery power pack system Battery power pack, Size a 88-797607-63 Rev Outline drawing, System Control Cabinet SCCT, 200-1200A 88-797613-71 Rev Outline drawing, System Control Cabinet SCCT, 1600-2000A 88-797613-78 Rev Outline drawing, System Control Cabinet SCCT, 2500-3000A 88-797613-73 Rev Outline drawing, System Control Cabinet SCCT, 4000A Base mounting patterns, System Control Cabinet SCCT, 4000A 96-797619-58A Rev 96-797619-66A Rev Control connection location diagram, Scct 96-797619-51A Rev 96-797619-60 Rev 96-797619-19A Rev 96-797619-20 Rev 96-797619-21 Rev 96-797619-130 Rev 96-797619-28 Rev 96-797619-128 Rev 96-797619-62 Rev 96-797619-90 Rev 96-797619-91 Rev 96-797619-52A Rev 96-797619-53A Rev 96-797619-54A Rev 96-797619-55A Rev 96-797619-56A Rev 96-797619-57A Rev 88-797616-09 Rev 88-797616-13 Rev 88-797616-07 Rev Outline drawing, remote status panel, surface mount Installation Drawings Data, Series 610, 500-750kVA, Multi-Module Systems Site planning data-600V input Site planning data-480V input System Control Cabinets Page Page Page Environmental Systems 800-543-2778 Outside the United States