Sun Microsystems 96257 Site Power Distribution Systems, Site Electrical Power Distribution System

Site Evaluation – Internal Considerations

Site Power Distribution Systems

The following elements of the site power distribution system should be evaluated when planning an installation of VSM5 system equipment.

System Design

A properly installed power distribution system is required to ensure safe operation of VSM5 system equipment. Power should be supplied from a feeder separate from one used for lighting, air conditioning, and other electrical systems.

Atypical input power configuration, shown in Figure 4-1, is either a five-wire high-voltage or a four-wire low-voltage type, with three-phase service coming from a service entrance or separately derived source, and with overcurrent protection and suitable grounding. A three-phase, five-wire distribution system provides the greatest configuration flexibility, since it allows power to be provided to both three-phase and single-phase equipment.

Figure 4-1. Site Electrical Power Distribution System

Computer Room	Remotely Operated
Power Panel	Power Service Disconnect

Incoming Three-phase Power from service entrance or separately derived system with appropriate over-current protection and suitable ground

Ground Terminal Bar (bonded to enclosure) Same size as neutral

Neutral	Only valid at
	service entrance
	or separately
	derived system
	(transformer)

Ground

Service Entrance

Ground or Suitable

Building Ground

Note: Bounding of neutral and ground at other points is Illegal.

Ledgend:

Insulated Green Wire Ground

Phase Wires and Neutral

Neutral Bus

Circuit Breakers of

Appropriate Size

Branch Circuits

	*For loads requiring a
	neutral attach computer/data
	120V * processing equipment only
	Single
208/240V Phase
208/240V	Single
	Phase
3-Phase
208/240V (4-wire)	Customer Supplied
3-Phase	Receptacles/Connectors-
(5-wire)	in Accordance with

Local Codes

A502_046

96257	Sun Confidential: Internal Only	4-49
	Revision A