Compaq 226824-001 - ProLiant - ML750 Basics Manual
Power basics for it professionals
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Power basics for IT professionals
technology brief
Abstract.............................................................................................................................................. 2
Introduction......................................................................................................................................... 2
General terms ..................................................................................................................................... 2
Power generation, transmission, and distribution ..................................................................................... 3
Generation and transmission ............................................................................................................. 3
Present-day power distribution infrastructure ........................................................................................ 4
Regional power distribution............................................................................................................... 5
Power distribution at the site .............................................................................................................. 5
Power factor correction ................................................................................................................... 14
Leakage current ............................................................................................................................. 15
Grounding .................................................................................................................................... 15
Power utilization ................................................................................................................................ 17
Three-phase versus single-phase power ............................................................................................. 17
Panel distribution ........................................................................................................................... 18
Distribution within the rack .............................................................................................................. 19
Uninterruptible Power Supplies (UPS)................................................................................................ 20
Wiring methods ............................................................................................................................. 21
High-line or low-line input voltage .................................................................................................... 23
Inrush current................................................................................................................................. 23
Plugs and receptacles ..................................................................................................................... 24
Power trends and strategies ................................................................................................................ 24
Tools for powering the data center....................................................................................................... 26
Appendix A. United States design standards......................................................................................... 27
Appendix B. Voltages and frequencies of individual countries ................................................................. 28
Appendix C. Plug and socket types...................................................................................................... 31
Glossary ........................................................................................................................................... 35
For more information.......................................................................................................................... 44
Call to action .................................................................................................................................... 44
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Summary of Contents for Compaq 226824-001 - ProLiant - ML750
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Page 1: Table Of Contents
Power basics for IT professionals technology brief Abstract.............................. 2 Introduction............................2 General terms ............................. 2 Power generation, transmission, and distribution ..................3 Generation and transmission ......................3 Present-day power distribution infrastructure ..................4 Regional power distribution....................... 5 Power distribution at the site ......................5 Power factor correction ........................ -
Page 2: Abstract
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. -
Page 3: Power Generation, Transmission, And Distribution
Figure 2 shows the sine waves for a three-phase transmission. Figure 2 also shows how the three phases can be delivered using a Wye transformer. At the distribution center the three-phase voltage is stepped down to the required voltage and delivered to the local customers either as single-phase or three-phase AC power. -
Page 4: Present-Day Power Distribution Infrastructure
coordinating committees or organizations. The data center administrator can research the history of service availability from the local utility or the grid manager. Planning for temporary power generation and for using uninterruptible power supplies (UPSs) to back up the electric power system can eliminate interruptions due to distance or weather conditions. -
Page 5: Regional Power Distribution
minimize transmission losses. Three-phase alternating current from the generating station is increased to the required transmission voltage by step-up transformers; it is stepped back down once it reaches the load center for local distribution. Regional power distribution Distribution voltages range from 2.4kV to 34.5kV in North America; the most common voltages are 2400V, 4160V, 7200V, 12470V, 24kV and 34.5kV. - Page 6 Figure 4 shows the HP servers connected to single-phase power. Figure 4. North American power distribution with a backup generator and an automatic transfer switch with HP servers at single phase...
- Page 7 The only difference between Figures 4 and 5 is that Figure 4 shows the HP servers connected to three- phase power. Figure 5. North American power distribution with a backup generator and an automatic transfer switch with HP servers at three phase Figure 6 depicts a UPS for the server room in addition to many of the pieces shown in Figures 4 and 5.
- Page 8 Figure 6. North America power distribution with a backup generator and a UPS with HP servers at single phase...
- Page 9 The only difference between Figures 6 and 7 is that Figure 7 shows HP servers connected to three- phase UPS power. Figure 7. North American power distribution with a backup generator and a UPS with HP servers at three phase Figures 8 through 11 depict the standard European or Asian method using International Electrotechnical Commission (IEC) Standards for serving single phase and three-phase power using a backup generator with either an automatic transfer switch or a UPS.
- Page 10 European and Asian electrical symbols and nomenclature. Figure 8 shows the HP servers connected to single-phase power. Figure 8. European or Asian power distribution with a backup generator and an automatic transfer switch with HP servers at single phase...
- Page 11 The only difference between Figures 8 and 9 is that Figure 9 shows the HP servers connected to three- phase power. Figure 9. European or Asian power distribution with a backup generator and an automatic transfer switch with HP servers at three phase...
- Page 12 Figure 10 depicts a UPS for the server room in addition to many of the pieces shown in Figures 8 and 9. This UPS can supply power from three sources: normal power, temporary power, or battery backup. In the event of a loss of power, the UPS always allows power to the server room power panel.
- Page 13 The only difference between Figures 10 and 11 is that Figure 11 shows HP servers connected to three-phase UPS power. Figure 11. European or Asian power distribution with a backup generator and a UPS with HP servers at three phase...
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Page 14: Power Factor Correction
Power factor correction Before computing and storage devices can use electrical power, the AC provided from the source must be transformed to direct current (DC) by a power supply. The term power indicates the rate at which the electricity does work, such as running a central processing unit (CPU) or turning a cooling fan. -
Page 15: Leakage Current
unity (~1), which allows smaller circuits to be used. Using energy-efficient PFC devices, includin UPSs, can lead to significant cost savings for data centers where the incoming feeds are measured megawatts. As a standard feature, power supplies for ProLiant servers all contain circuitry to correct the power factor (that is, to bring input current and voltage into phase). - Page 16 Figure 13. Typical grounding of commercial or industrial building In the United States, the National Electric Code specifies the standard grounding system resistivity value of 25 ohms. It is common practice that large industrial plants and commercial buildings require maximum 5-ohm resistivity values in the ground grid. Instrument systems generally require only 1-ohm resistivity values.
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Page 17: Power Utilization
For example, the Emerald Book addresses the common modern-day grounding issues and difficult installation scenarios for grounding sensitive electronic equipment. The IEEE standards books, the color books, listed in Table 1 can be purchased from IEEE Standards Association. For more information, see the following URL: http://standards.ieee.org. -
Page 18: Panel Distribution
below shows three-phase and single-phase power delivery for some common circuit sizes in North America. Table 3 shows similar information for other countries. Please see the section entitled, “Panel distribution,” for an example of the greater efficiency of three- phase power. Also see the section entitled, “Wiring Methods,” for more information about power calculations in North America and in Europe, the Middle East, and Africa (EMEA). -
Page 19: Distribution Within The Rack
requires four PDUs. Since each PDU requires two poles off the distribution panel to get 208 V, each cabinet requires four breakers and eight poles. With these requirements, the 84-pole panel will provide redundant power for 10 cabinets and 210 servers using today’s distribution method. A 10- cabinet implementation will use only 86 kVA of the 150 kVA possible from the panel. -
Page 20: Uninterruptible Power Supplies (Ups)
For more information about the extensive PDU product portfolio, please see the following URLs: http://h18004.www1.hp.com/products/servers/proliantstorage/power-protection/pdu.html. www.hp.com/servers/technology. And, for more information about the use of three-phase power within the rack, please see the technical brief entitled, “Critical factors in intra-rack power distribution planning for high density systems”... -
Page 21: Wiring Methods
Wiring methods A common and economical method of supplying power to data centers is to deliver three-phase 208V AC service, which carries 208V through any two transformer windings and 120V between any phase and neutral, as shown in Figure 14. Figure 14. - Page 22 Table 4. Power limitations of commercial branch circuits in North America Branch Voltage Branch Circuit Maximum Load Maximum Power Breaker (80% per National Electric Code) 120V, single-phase 1,920 VA 120V, single-phase 2,880 VA 240V, single-phase 3,840 VA 240V, single-phase 5,760 VA 240V, single-phase 7,680 VA 240V, single-phase...
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Page 23: High-Line Or Low-Line Input Voltage
Under steady-state operating conditions and for reliable operation, the full-load current should not exceed 80 percent of the rated current. Once AC power reaches a server rack, a power supply converts AC power to DC (for example, 208VAC to 12 VDC to power a server blade) and when necessary, a converter provides DC-to-DC voltage conversion for internal operations. -
Page 24: Plugs And Receptacles
area of a data center to prevent the cascading effects of inrush, should a site experience a power loss. Plugs and receptacles Two types of power cords provide connections between server products and utility power: power cord assemblies and jumper cable assemblies. In general, power cord assemblies provide the main connection from the AC power outlet to the server equipment, and they meet the standards for the country from which they are ordered. - Page 25 3,000 watts per rack. As of 2005, it appears that data centers averaged eight to twelve servers (2U to 3U each) per rack and wattage of 5 to 6 kilowatts per rack. It is important to remember that with the increase in density 1U and server blade racks can draw two to three times that amount, or 10 to 18 kilowatts of power.
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Page 26: Tools For Powering The Data Center
Tools for powering the data center To help customers plan and configure efficient and reliable data centers, HP offers several tools. These include: HP Power Calculator software to calculate the amount of power required and the amount of • heat to be dissipated by HP ProLiant servers (http://h30099.www3.hp.com/configurator/calc/Power%20Calculator%20Catalog.xls The HP eCo-Enterprise Configurator to provide factory default racking for the HP hardware •... -
Page 27: Appendix A. United States Design Standards
Appendix A. United States design standards There are basic standards to adhere to when designing electrical systems. The only standards to be used in the United States are the American National Standards Institute (ANSI), National Electrical Manufacturers Association (NEMA), and Institute of Electrical and Electronics Engineers (IEEE) Standards. -
Page 28: Appendix B. Voltages And Frequencies Of Individual Countries
Appendix B. Voltages and frequencies of individual countries Afghanistan 220 V 50 Hz Cambodia 230 V 50 Hz Albania 230 V 50 Hz Cameroon 220 V 50 Hz Algeria 230 V 50 Hz Canada 120 V 60 Hz American Samoa 120 V 60 Hz Canary Islands... - Page 29 Faeroe Islands 230 V 50 Hz Jordan 230 V 50 Hz Falkland Islands 240 V 50 Hz Kenya 240 V 50 Hz Fiji 240 V 50 Hz Kazakhstan 220 V 50 Hz Finland 230 V 50 Hz Kiribati 240 V 50 Hz France 230 V...
- Page 30 Myanmar (formerly Burma) 230 V 50 Hz Slovakia 230 V 50 Hz Namibia 220 V 50 Hz Slovenia 230 V 50 Hz Nauru 240 V 50 Hz Somalia 220 V 50 Hz Nepal 230 V 50 Hz South Africa 230 V 50 Hz Netherlands 230 V...
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Page 31: Appendix C. Plug And Socket Types
Appendix C. Plug and socket types The industry uses two primary connector standards: NEMA and IEC. North America uses the NEMA standard. In the NEMA nomenclature for plugs and sockets (for example, NEMA L6-30P or NEMA L5-30P): • L means a twist-locking (as opposed to a push-in) connection •... - Page 32 • C19/20 means 16-amp connectors (odd for female, even for male) Inside a rack, only two connectors are used for distributing power: Those are the NEMA 5-15 for low- voltage, 120-V, applications, and the IEC 320, C13/C14. IEC 309 pin-and-sleeve connectors are commonly used on international PDUs, servers, and storage devices, and they are beginning to be used in North America.
- Page 33 Plug Alternate Country Description Voltage Rating [1] Profile Application (see notes) Std. Italian High-line Std. Australian/NZ. High-line — Std. India High-line — Std. S. African High-line — Std. Japanese Low-line — Std. Danish High-line — Std. Swiss High-line — Std. Argentinean High-line —...
- Page 34 Table C-2. HP jumper cable assemblies IEC Description Type of Plug Type of (each assembly) (to PDU or UPS) Receptacle (to Server) 10A, IEC; IEC C14 IEC C13 4.5 ft (1.37 m)1.5 ft (0.5 m) 10A, IEC; IEC C14 IEC C13 10 ft (3.0 m) 10A, IEC;...
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Page 35: Glossary
Glossary A: ampere AC: Alternating current Alternating current (AC): An electric current that reverses flow (positive or negative polarity) in a cyclical manner that resembles a sine wave. American National Standards Institute (ANSI): A private, non-profit standards organization that produces industrial standards in the United States, ANSI is a member of IEC. (For the ANSI website, http://www.ansi.org/) American Wire Gauge (AWG): A common standard of measurement for the diameter of wires, especially electric-conductive wires. - Page 36 Capacitance: The ability to store an electrical charge, measured in farads. See Farad. CEE: Abbreviated from International Commission for Conformity Certification of Electrical Equipment, subsumed in 1985 into the International Electrotechnical Commission (IEC). See International Electrotechnical Commission. CENELEC: Comité Européen de Normalisation Electrotechnique, see below. Circuit: A conductor through which electrical current flows, or more practically, a combination of electrical components that have been assembled to perform a function.
- Page 37 Downflow cooling: A downflow cooling system delivers supply air under a raised floor where it is distributed to the heat source through perforated tiles. Alternatively, supply air is commonly discharged through plenum grilles. Dropout: A decrease in voltage (volts) or current (amperes) anywhere, but usually describing a Backup loss of electric utility power.
- Page 38 High-line voltage: In a commercial setting, power that is 180-264V AC (200-240V AC nominal rating). High-line voltage is common in commercial applications in North America and is the AC appliance standard in the majority of other countries. Also referred to as high voltage. Hot: A live conductor that is carrying voltage.
- Page 39 Jumper cable assembly: The power connection between a server and intermediate equipment such as a power distribution unit. Usually a jumper cable employs IEC-type connectors. Kilovolt amperes (kVA): A term and method for rating electrical devices by multiplying the rated output (amperes) by the rated operating voltage (volts).
- Page 40 Neutral (cold) contact (conductor, core, line, pin, pole, prong, terminal): A power plug element that connects in most cases with the ground and is not dangerous outside of fault conditions (such as a broken neutral wire in the cable). It is wise to treat a neutral contact as a live contact throughout most installation practices.
- Page 41 Power distribution panel: See Distribution panel. Power distribution unit (PDU): A rack-mounted component that connects directly to the AC power infrastructure of a building. The PDU typically provides circuit-breaker protection for groups of AC outlets into which separate AC components of a rack are plugged. Some PDU designs offer primary/secondary switching.
- Page 42 Shielded-type cable: A cable in which the conductors (wires) are enclosed in a conducting envelope constructed so that virtually every point on the surface of the insulation is at ground potential. Short circuit: An undesired electrical connection or crossover between two or more components (such as a live wire touching a ground, a neutral wire, or a device’s metal casing).
- Page 43 Uninterruptible power supply (UPS): A UPS is a battery-powered device that acts like a power supply for computers or servers during a power outage. A UPS typically extends uptime from 7 to 40 minutes or more (depending on server power loads and UPS configuration options). UPS: Uninterruptible power supply.
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Page 44: For More Information
“Cooling design: Walking the path to a cool http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00257 ProLiant server” 520/c00257520.pdf HP Power Calculators http://h30099.www3.hp.com/configurator/calc/Power%20Calculator%2 0Catalog.xls HP Power Calculators for HP BladeSystems http://www27.compaq.com/sb/ProLiantBladePowerSizer/index.asp customers “Power Regulator for ProLiant servers” http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00593 374/c00593374.pdf “Selecting power cords and jumper cables http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00130 for use with HP ProLiant servers and 729/c00130729.pdf...