HP ProLiant SL270s HP ProLiant SL Servers Planning Guide - Page 25

Non-redundant power For equipment supplied by a single source of power, connect all components to the same power distribution device (PDU or UPS). The power distribution device should be suitably rated for the connected load. If the total load exceeds the rating of the power distribution device, obtain a suitable rated device or add a second power distribution device and divide the load equally between the devices. Line voltage selection All HP products that are optimized for rack mounting have wide-range power supply inputs designed to operate at a voltage range of 100-240V. HP recommends operating rack-optimized equipment with high line voltage (200 V AC to 240V AC). Benefits of high line voltage operation include the following: • Power supplies run more efficiently and waste less power when operating at 200V to 240 V, thus saving electrical power. • Greater capacity is available in a single rack. For the same size circuit, almost twice the power can be delivered to a rack at high line versus low line. For example, a branch circuit that is 115 V 30A can deliver 2760 VA (derated) to a rack, while a branch circuit that is 208 V 30A can deliver 4992VA (de-rated) to a rack. • Some products require 200 V to 240 V input power to operate at their full-rated capacity. • The HP 1200W High Efficiency Power Supply operates only at 200 V AC to 240V AC and provides significantly higher efficiency than the 750 W power supply. • Power supplies run cooler at higher input voltages, last longer, and improve overall availability. Also, because they run cooler, they produce less heat which helps to lower cooling costs. • Keeping input currents lower allows the use of smaller, more standardized power connections. Distribution hardware This section describes wire selection and the types of raceways (electrical conduits) used in the distribution system. Wire selection Use copper conductors instead of aluminum, because aluminum's coefficient of expansion differs significantly from that of other metals used in power hardware. Because of this difference, aluminum conductors can cause connector hardware to work loose, overheat, and fail. Raceway systems (electrical conduits) (LAHJ) Raceways (electrical conduits) form part of the protective ground path for personnel and equipment. Raceways protect the wiring from accidental damage and also provide a heatsink for the wires. Any of the following types may be used: • EMT thin-wall tubing • Rigid (metal) conduit • Liquidtight with RFI shield grounded (most commonly used under raised floors) • Armored cable Power requirements and considerations 25