Emergency power system

A backup generator for a large apartment building
A backup power fuel cell for telecom applications
A portable emergency power generator in a shipping container

An emergency power system is an independent source of electrical power that supports important electrical systems on loss of normal power supply. A standby power system may include a standby generator, batteries and other apparatus. Emergency power systems are installed to protect life and property from the consequences of loss of primary electric power supply. It is a type of continual power system.

They find uses in a wide variety of settings from homes to hospitals, scientific laboratories, data centers,[1] telecommunication[2] equipment and ships. Emergency power systems can rely on generators, deep-cycle batteries, flywheel energy storage[3] or fuel cells.[4][5]

History

Emergency power systems were used as early as World War II on naval ships. In combat, a ship may lose the function of its boilers, which power the steam turbines for the ship's generator. In such a case, one or more diesel engines are used to drive back-up generators. Early transfer switches relied on manual operation; two switches would be placed horizontally, in line and the "on" position facing each other. a rod is placed in between. In order to operate the switch one source must be turned off, the rod moved to the other side and the other source turned on.

Operation in buildings

Emergency power electric generator in a water purification plant, driven by a marine propulsion diesel engine
Lead–acid deep-cycle batteries stored in a base station as an emergency power, system high-availability emergency power systems like hospitals and stand-alone power systems

Mains power can be lost due to downed lines, malfunctions at a sub-station, inclement weather, planned blackouts or in extreme cases a grid-wide failure. In modern buildings, most emergency power systems have been and are still based on generators. Usually, these generators are Diesel engine driven, although smaller buildings may use a gasoline engine driven generator.

Some larger building have gas turbines, but they can take 5 or up to 30 minutes to produce power.[6]

Lately, more use is being made of deep cycle batteries and other technologies such as flywheel energy storage or fuel cells. These latter systems do not produce polluting gases, thereby allowing the placement to be done within the building. Also, as a second advantage, they do not require a separate shed to be built for fuel storage.[7]

With regular generators, an automatic transfer switch is used to connect emergency power. One side is connected to both the normal power feed and the emergency power feed; and the other side is connected to the load designated as emergency. If no electricity comes in on the normal side, the transfer switch uses a solenoid to throw a triple pole, double throw switch. This switches the feed from normal to emergency power. The loss of normal power also triggers a battery operated starter system to start the generator, similar to using a car battery to start an engine. Once the transfer switch is switched and the generator starts, the building's emergency power comes back on (after going off when normal power was lost).

Unlike emergency lights, emergency lighting is not a type of light fixture; it is a pattern of the building's normal lights that provides a path of lights to allow for safe exit, or lights up service areas such as mechanical rooms and electric rooms. Exit signs, Fire alarm systems (that are not on back up batteries) and the electric motor pumps for the fire sprinklers are almost always on emergency power. Other equipment on emergency power may include smoke isolation dampers, smoke evacuation fans, elevators, handicap doors and outlets in service areas. Hospitals use emergency power outlets to power life support systems and monitoring equipment. Some buildings may even use emergency power as part of normal operations, such as a theater using it to power show equipment in accordance with the principle of "the show must go on".

Operation in aviation

A view of an Aviation 501-1228-04 Emergency Power Supply by Repaero

The use of Emergency power systems in aviation can be either in the aircraft or on the ground.

In commercial and military aircraft it is critical to maintain power to essential systems during an emergency. This can be done via Ram air turbines or battery emergency power supplies which enables pilots to maintain radio contact and continue to navigate using MFD, GPS, VOR receiver or directional gyro during for more than an hour.

Localizer, glideslope, and other instrument landing aids (such as microwave transmitters) are both high power consumers and mission-critical, and cannot be reliably operated from a battery supply, even for short periods. Hence, when absolute reliability is required (such as when Category 3 operations are in force at the airport) it is usual to run the system from a diesel generator with automatic switchover to the mains supply should the generator fail. This avoids any interruption to transmission while a generator is brought up to operating speed.

This is opposed to the typical view of emergency power systems, where the backup generators are seen as secondary to the mains electrical supply.

Electronic device protection

Computers, communication networks, and other modern electronic devices need not only power, but also a steady flow of it to continue to operate. If the source voltage drops significantly or drops out completely, these devices will fail, even if the power loss is only for a fraction of a second. Because of this, even a generator back-up does not provide protection because of the start-up time involved.

To achieve more comprehensive loss protection, extra equipment such as surge protectors, inverters, or sometimes a complete uninterruptible power supply (UPS) is used. UPS systems can be local (to one device or one power outlet) or may extend building-wide. A local UPS is a small box that fits under a desk or a telecom rack and powers a small number of devices. A building-wide UPS may take any of several different forms, depending on the application. It directly feeds a system of outlets designated as UPS feed and can power a large number of devices.

Since telephone exchanges use DC, the building's battery room is generally wired directly to the consuming equipment and floats continuously on the output of the rectifiers that normally supply DC rectified from utility power. When utility power fails, the battery carries the load without needing to switch. With this simple though somewhat expensive system, some exchanges have never lost power for a moment since the 1920s.

Structure and operation in utility stations

Diagram of a redundant power supply system.

In recent years, large units of a utility power station are usually designed on a unit system basis in which the required devices, including the boiler, the turbine generator unit, and its power (step up) and unit (auxiliary) transformer are solidly connected as one unit. A less common set-up consists of two units grouped together with one common station auxiliary. As each turbine generator unit has its own attached unit auxiliary transformer, it is connected to the circuit automatically. For starting the unit, the auxiliaries are supplied with power by another unit (auxiliary) transformer or station auxiliary transformer. The period of switching from the first unit transformer to the next unit is designed for automatic, instantaneous operation in times when the emergency power system needs to kick in. It is imperative that the power to unit auxiliaries not fail during a station shutdown (an occurrence known as black-out when all regular units temporarily fail). Instead, during shutdowns the grid is expected to remain operational. When problems occur, it is usually due to reverse power relays and frequency-operated relays on grid lines due to severe grid disturbances. Under these circumstances, the emergency station supply must kick in to avoid damage to any equipment and to prevent hazardous situations such as the release of hydrogen gas from generators to the local environment.

Controlling the emergency power system

For a 208 VAC emergency supply system, a central battery system with automatic controls, located in the power station building, is used to avoid long electric supply wires. This central battery system consists of lead-acid battery cell units to make up a 12 or 24 VDC system as well as stand-by cells, each with its own battery charging unit. Also needed are a voltage sensing unit capable of receiving 208 VAC and an automatic system that is able to signal to and activate the emergency supply circuit in case of failure of 208 VAC station supply.

References

  1. ^ Fuel cell in the data center Munich Archived 2008-09-20 at the Wayback Machine
  2. ^ India orders 10.000 fuel cell emergency power systems[permanent dead link]
  3. ^ Dorf, Richard C. (14 December 2018). The Electrical Engineering Handbook - Six Volume Set. CRC Press. ISBN 978-1-4200-4975-6.
  4. ^ Fuel Cells in Backup Power Applications
  5. ^ DOE Fuel Cells for Backup Power
  6. ^ [1] Gas Turbines In Simple Cycle & Combined Cycle Applications | Claire M. Soares
  7. ^ "Advantages of deep-cycle batteries over generators". April 2000.

Read other articles:

Regno di Napoli ←  1282 – 1816  → (Details) Kaart Napels in 1360 Algemene gegevens Hoofdstad Napels Talen Italiaans Religie(s) Rooms-katholiek Regering Regeringsvorm Monarchie Dynastie Hohenstaufen, Habsburg, Anjou, Aragón, Bourbon Staatshoofd Koning Het koninkrijk Napels, bestaande uit het zuidelijk deel van het Apennijns Schiereiland, was het restant van het oude koninkrijk Sicilië na de afscheiding van het eiland Sicilië als gevolg van de opstand van de Sicilia...

 

هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (يناير 2015) المختبر آي بي إم للأبحاث في زيورخالشعارالتاريخالتأسيس 1956 الجوائز  EPS Historic Site (en) [1] الإطارالنوع معهد بحوث الوضع القانوني limited liability company (en) المقر الرئيسي

 

Beijing Subway station Ming Tombs[1]十三陵景区PlatformGeneral informationLocationJiantou Village, Shisanling, Changping District, BeijingChinaCoordinates40°14′25″N 116°12′28″E / 40.240255°N 116.207729°E / 40.240255; 116.207729Operated byBeijing Mass Transit Railway Operation Corporation LimitedLine(s)     Changping linePlatforms2 (1 island platform)Tracks2ConstructionStructure typeUndergroundAccessibleYesHistoryOpenedDe...

TakePart, LLCTypeDigital media companyFounded2008HeadquartersLos Angeles, California, U.S.ParentParticipant Media TakePart was a website operated by Participant Media, a motion picture studio that focuses on issues of social justice. TakePart was founded in 2008 to promote Participant Media's films as well as make viewers aware of the social advocacy efforts of Participant's outreach partners.[1] The operation has shut down.[2] About the site TakePart produced a website with a...

 

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Hidili Industry International Development Limited – news · newspapers · books · scholar · JSTOR (October 2016) (Learn how and when to remove this template message) Hidili Industry International Development Limited 恒鼎实业国际发展有限公司TypePrivate...

 

Town in the Nabatieh Governorate, Lebanon This article's lead section may be too long. Please read the length guidelines and help move details into the article's body. (January 2023) Place in Nabatieh Governorate, LebanonHasbaya حاصبياHasbaya CitadelHasbayaLocation in LebanonCoordinates: 33°23′52″N 35°40′57″E / 33.39778°N 35.68250°E / 33.39778; 35.68250Country LebanonGovernorateNabatieh GovernorateDistrictHasbaya DistrictElevation750 m (2,46...

2010 Yemeni army offensive Some of this article's listed sources may not be reliable. Please help this article by looking for better, more reliable sources. Unreliable citations may be challenged or deleted. (October 2012) (Learn how and when to remove this template message) First Battle of LawdarPart of Al-Qaeda insurgency in YemenDate19–25 August 2010(6 days)LocationLawdar (Abyan Governorate)Status Yemeni victory[2] Yemeni armed forces regain control of LawdarBelligerents ...

 

Political party in Turkey National Struggle Party Milli Mücadele PartisiAbbreviationMMPLeaderAhmet KayaFoundedNovember 25, 2014 (2014-11-25)HeadquartersAnkaraMembership (2023) 0[1]IdeologyTurkish nationalismKemalismColours  dark redPolitics of TurkeyPolitical partiesElections The National Struggle Party (Turkish: Milli Mücadele Partisi, abbreviated MMP) is a Nationalist political party in Turkey. It was formed by Ahmet Kaya, whose Turkish nationalism has been...

 

Dravidian language native to South India and Sri Lanka TamilTamiḻதமிழ்The word Tamil in Tamil scriptPronunciation[t̪amiɻ] ⓘNative toIndia and Sri LankaRegionTamil Nadu[a] (India)Northern and Eastern Provinces (Sri Lanka)EthnicityTamilsSri Lankan MoorsNative speakersL1: 78 million (2011–2019)[1]L2: 8 million (2011)[1]Language familyDravidian SouthernTamil–KannadaTamil–KodaguTamil–MalayalamTamil languagesTamilEarly formsOld Tamil...

Seán MacBride (Amsterdam, 1984) Seán MacBride (1904-1988) adalah juri dan politikus Irlandia. Ibunya bernama Maud Gonne, seorang tokoh terkenal dalam budaya Irlandia pada abad ke-19. Pada 1946 MacBride mendirikan Clann na Poblachta, sebuah partai nasionalis di parlemen Irlandia Dáil Éireann dan memenangkan kursi pada 1947. Namun pada pemilihan umum Irlandia, 1948 hanya 10 kursi yang dimenangkan partai itu sehingga berkoalisi dengan. Fine Gael, Partai Buruh Irlandia, Buruh Nasional dan par...

 

1982年アジア競技大会におけるバスケットボール競技(1982ねんアジアきょうぎたいかいにおけるバスケットボールきょうぎ)は11月19日から12月3日まで行われた。 男子 最終結果 順位 国 金 韓国 銀 中国 銅 日本 4 フィリピン 5 北朝鮮 6 クウェート 7 マレーシア 8 インド 9 イラク 10 バーレーン 11 アラブ首長国連邦 12 南イエメン 13 北イエメン 女子 最終結果 順位 国 金 中国...

 

This article uses bare URLs, which are uninformative and vulnerable to link rot. Please consider converting them to full citations to ensure the article remains verifiable and maintains a consistent citation style. Several templates and tools are available to assist in formatting, such as reFill (documentation) and Citation bot (documentation). (September 2022) (Learn how and when to remove this template message) Academic journalNature Reviews MicrobiologyDisciplineMicrobiologyLanguageEnglish...

Theater in Minneapolis, Minnesota, U.S. Orpheum TheatreHennepin TheaterThe Orpheum Theatre at nightAddress910 Hennepin AvenueMinneapolis, MinnesotaUnited StatesOwnerHennepin Theatre TrustOperatorHistoric Theatre GroupCapacity2,579ConstructionOpened1921Reopened1993Websitewww.hennepintheatretrust.org/our-theatres/orpheum-theatre/ Hennepin TheatreU.S. National Register of Historic Places Coordinates44°58′36.37″N 93°16′38.97″W / 44.9767694°N 93.2774917°W / 44.9...

 

Indian molecular biologist Subhadeep ChatterjeeBornWest Bengal, IndiaNationalityIndianAlma materGuru Nanak Dev UniversityCentre for Cellular and Molecular BiologyUniversity of California, BerkeleyKnown forStudies on plant-microbe interactionsAwards2017/18 N-BIOS Prize2020: Shanti Swarup Bhatnagar PrizeScientific careerFieldsMolecular biologyInstitutionsCentre for DNA Fingerprinting and DiagnosticsDoctoral advisorRamesh V. SontiSteven E. Lindow Subhadeep Chatterjee is an Indian ...

 

Russian-born dancer and choreographer Xenia Borovansky, in the 1940s. Xenia Nikolaeva Smirnova Krüger Borovansky (August 10, 1903 — November 25, 1985) was a Russian-born dancer and choreographer, based in Australia after 1939. She was principal teacher at the Melbourne Academy of Russian Ballet, and active in running the Borovansky Ballet. Early life Xenia Nikolaeva Smirnova was born in Moscow. Her mother Aleksandra Adrianovna Smirnova (née Nikolaeva) was a dancer; her father Nikolay Vasi...

Current denomination of Australian currency Twenty Dollars(Australia)Value20 Australian dollarsWidth144 mmHeight65 mmSecurity featuresWindow, WatermarkMaterial usedPolymerYears of printing1994–1998, 2002–2003, 2005–2008, 2010, 2013, 2019–2020ObverseDesignMary ReibeyDesigneremerystudioDesign date9 October 2019ReverseDesignJohn FlynnDesigneremerystudioDesign date9 October 2019 The Australian twenty-dollar note was issued when the currency was changed from the Australian po...

 

Totò, Fabrizi e i giovani d'oggiAldo Fabrizi e Totò in una scena del filmPaese di produzioneItalia Anno1960 Durata92 min Dati tecniciB/Nrapporto: 2,35:1 Generecommedia RegiaMario Mattoli SoggettoCastellano e Pipolo SceneggiaturaCastellano e Pipolo ProduttoreIsidoro Broggi e Renato Libassi Casa di produzioneD.D.L. Distribuzione in italianoCine Produzioni Astoria FotografiaAlvaro Mancori MontaggioGisa Radicchi Levi MusicheGianni Ferrio ScenografiaAlberto Boccianti CostumiGiuliano Papi TruccoG...

 

Japanese actor, voice actor and singer Ryūsei Nakao中尾 隆聖Ryūsei Nakao at Nan Desu Kan 2017BornTomoharu Takeo (1951-02-05) February 5, 1951 (age 72)Tokyo, JapanOther names Tomoharu Minamiya Tomo-chan Occupations Actor voice actor singer Years active1954–presentAgent81 ProduceChildren2, including Kazuma Takeo Tomoharu Takeo (竹尾 智晴, Takeo Tomoharu, born February 5, 1951), known by his stage name Ryūsei Nakao (中尾 隆聖, Nakao Ryūsei), is a Japanese actor, ...

У этого термина существуют и другие значения, см. Альберта (значения). Провинция КанадыАльбертаангл. Alberta Флаг Альберты Герб Альберты Девиз: Fortis et Liber «Сильный и свободный» Страна  Канада Столица Эдмонтон Крупнейший город Калгари Население (01.01.2016) 4 231 959 чел...

 

Thomas T. MackieBornMay 10, 1895Great Barrington, MassachusettsDiedOctober 5, 1955 (Aged 60)Alma materHarvard (1918), Columbia University (1924)OccupationResearch physicianNotable workManual of Tropical Medicine[1] (textbook)SpouseCarolyn Bleecker Van Courtlandt. May 31, 1921 – July 7, 1941 (divorce) Janet Welch March 14, 1942 – December 4, 1951 (divorce) Helen Holme Warnok. December 19, 1951 – October 5, 1955 (his death) Thomas T. Mackie (1895-1955) was a research/public h...

 

Strategi Solo vs Squad di Free Fire: Cara Menang Mudah!