HP DL360 Power basics for IT professionals - Page 2

Abstract, Introduction, General terms

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Abstract In the next decade, power, with its attendant heating, cooling, cost, reliability and dependability issues, will be the greatest challenge for the vast majority of data center operations. IT professionals attempting to deal with the power challenge need a working understanding of the power terms, concepts, and facts covered in this paper. This paper is intended primarily as an aid to IT professionals who are not fully familiar with power and its general concepts. The paper offers basic information about power in data centers and other IT environments. It explains how power is generated, transmitted, and delivered to IT operations, especially the data center. It also explains the importance of anticipating future IT growth and the need to provide adequate power to support that growth. This paper provides definitions and explanations of electric power in its most general and typical usage and implementation. The paper does not cover exhaustive details about exceptions to general practices. Introduction Electric power-its generation, transmission, distribution and ultimate use by HP ProLiant servers-is a complex supply chain. Customers must understand and consider a host of power terms, standards, and technical issues to enable their data centers to function as efficiently and economically as possible, now and in the future. This understanding becomes critical as the density of server configurations increases in the next few years. This paper provides an explanation of basic power concepts, terms, and introduction to general concepts for power distribution to IT data centers. It includes an extensive glossary for definitions of common terms. Finally, the "For More Information" section identifies additional references to standards and to technology briefs on specific power-related topics. General terms Alternating current (AC) is typically expressed in terms of voltage amplitude in volts and current amplitude in amperes. Its waveform is a sine wave with properties of length (described as cycles), and of height (described as amplitude) as illustrated in Figure 1. Figure 1. Properties of single-phase AC power Single-Phase Electrical Current Amplitude Cy1cle Wavelength Frequency is the number of sine wave cycles that are completed in a one-second period. The frequency of electricity is measured in Hertz (Hz); one Hz equals one cycle per second. The voltage of an AC 50-Hz power circuit will vary from zero to maximum in each direction (negative potential to positive potential) 50 times per second; the voltage of an AC, 60-Hz power circuit will vary from zero to maximum in each direction 60 times per second. Generating stations produce AC power using three-phase generators. These three-phase waveforms are 120 degrees apart and are transmitted as three-phase power after stepping-up the voltage. 2

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Abstract
In the next decade, power, with its attendant heating, cooling, cost, reliability and dependability
issues, will be the greatest challenge for the vast majority of data center operations. IT professionals
attempting to deal with the power challenge need a working understanding of the power terms,
concepts, and facts covered in this paper.
This paper is intended primarily as an aid to IT professionals who are not fully familiar with power
and its general concepts. The paper offers basic information about power in data centers and other IT
environments. It explains how power is generated, transmitted, and delivered to IT operations,
especially the data center. It also explains the importance of anticipating future IT growth and the
need to provide adequate power to support that growth. This paper provides definitions and
explanations of electric power in its most general and typical usage and implementation. The paper
does not cover exhaustive details about exceptions to general practices.
Introduction
Electric power—its generation, transmission, distribution and ultimate use by HP ProLiant servers—is a
complex supply chain. Customers must understand and consider a host of power terms, standards,
and technical issues to enable their data centers to function as efficiently and economically as
possible, now and in the future. This understanding becomes critical as the density of server
configurations increases in the next few years.
This paper provides an explanation of basic power concepts, terms, and introduction to general
concepts for power distribution to IT data centers. It includes an extensive glossary for definitions of
common terms. Finally, the “For More Information” section identifies additional references to
standards and to technology briefs on specific power-related topics.
General terms
Alternating current (AC) is typically expressed in terms of voltage amplitude in volts and current
amplitude in amperes.
Its waveform is a sine wave with properties of length (described as cycles),
and of height (described as amplitude) as illustrated in Figure 1.
Figure 1.
Properties of single-phase AC power
Amplitude
1
Cycle
Single-Phase Electrical Current
Wavelength
Frequency is the number of sine wave cycles that are completed in a one-second period. The
frequency of electricity is measured in Hertz (Hz); one Hz equals one cycle per second. The voltage of
an AC 50-Hz power circuit will vary from zero to maximum in each direction (negative potential to
positive potential) 50 times per second; the voltage of an AC, 60-Hz power circuit will vary from zero
to maximum in each direction 60 times per second.
Generating stations produce AC power using three-phase generators.
These three-phase waveforms
are 120 degrees apart and are transmitted as three-phase power after stepping-up the voltage.