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{{Short description|Combination of an electrical generator and an engine in a single part}}
{{More footnotes needed|date=September 2023}}
{{Distinguish|text = [[motor–generator]], a device for converting electrical power to another form}}
[[File:Engine Generator Cart.jpg|thumb|Cart-mounted engine–generator being used at a construction site]]
An '''engine–generator''' is the combination of an [[electrical generator]] and an [[engine]] ([[prime mover (locomotive)|prime mover]]) mounted together to form a single piece of equipment. This combination is also called an ''engine–generator set'' or a ''gen-set''. In many contexts, the engine is taken for granted and the combined unit is simply called a ''generator''. An engine–generator may be a fixed installation, part of a vehicle, or made small enough to be portable.

==Components==
In addition to the engine and generator, engine–generators generally include a fuel supply, a constant engine speed regulator (governor) in diesel  and a generator [[volt]]age regulator, cooling and exhaust systems, and lubrication system. Units larger than about 1&nbsp;kW rating often have a battery and electric starter motor; very large units may start with compressed air supplied either to an air driven starter motor or introduced directly to the engine cylinders to initiate engine rotation. Standby power generating units often include an automatic starting system and a [[transfer switch]] to disconnect the load from the utility power source when there is a power failure and connect it to the generator. [[File:Cummins Onan Transfer Switch Model No. OTPCB-4494345.JPG|thumb|A Cummins Onan transfer switch]]

==Types==
Engine–generators are available in a wide range of power ratings. These include small, hand-portable units that can supply several hundred watts of power, hand-[[cart]] mounted units that can supply several thousand watts and [[wikt:stationary|stationary]] or [[Trailer (vehicle)|trailer]]-mounted units that can supply over a million watts. Regardless of the size, generators may run on [[gasoline]], [[Diesel fuel|diesel]], [[natural gas]], [[propane]], [[bio-diesel]], [[water]], [[sewage gas]] or [[hydrogen]].<ref>{{cite web|last1=Denis|first1=Linda|title=Portable Generator Specifications and Reviews|url=http://portablegeneratorsrated.com/|website=Portable Generators Rated|access-date=23 August 2016|date=1 January 2014}}</ref> Most of the smaller units are built to use gasoline (petrol) as a fuel, and the larger ones have various fuel types, including diesel, natural gas and propane (liquid or gas). Some engines may also operate on diesel and gas simultaneously ([[Bi-fuel conversion|bi-fuel operation]]).<ref>{{Cite web|title=Welder Generators|url=https://www.1stopweldingshop.com/Catalogue/Welding-Cutting/Welding-equipment/Genset-Engine-Drive-Welders|access-date=2021-07-27|website=AES Industrial Supplies Limited|language=en-GB}}</ref>

=== Engines ===
Many engine–generators use a [[reciprocating engine]], with fuels mentioned above. This can be a [[steam engine]], such as most coal-powered [[fossil-fuel power plant]]s use. Some engine–generators use a turbine as the engine, such as the [[gas turbine#Industrial gas turbines for power generation|industrial gas turbines]] used in [[peaking power plant]]s and the [[gas turbine#Microturbines|microturbines]] used in some [[hybrid electric bus]]es.

The generator [[volt]]age (volts), [[frequency]] (Hz) and [[electric power|power]] (watts) ratings are selected to suit the load that will be connected.  Portable engine–generators may require an external [[power conditioner]] to safely operate some types of electronic equipment.

Engine-driven generators fueled on natural gas fuel often form the heart of small-scale (less than 1,000&nbsp;kW) [[combined heat and power]] installations.

=== Three phase ===
There are only a few [[wikt:portable|portable]] three-phase generator models available in the US. Most of the portable units available are [[single-phase generator]]s and most of the three-phase generators manufactured are large industrial type generators. In other countries where three-phase power is more common in households, portable generators are available from a few kW and upwards.

=== Inverter generator ===
Small portable generators may use an [[inverter (electrical)|inverter]]. Inverter models can run at slower RPMs to generate the power that is necessary, thus reducing the noise of the engine and making it more fuel-efficient. Inverter generators are best to power sensitive electronic devices such as computers and lights that use a ballast, as they have a low [[total harmonic distortion]].

Since the load on the electric generator causes the speed of the engine to fall, this has an adverse effect on the frequency and voltage of the electrical output. By using an electronic inverter to produce the required AC output, its voltage and frequency can be stable over the power range of the generator.

Another advantage is that the generated electric power from the engine-driven generator can be a polyphase output at a higher frequency and at a waveform more suitable for rectification to produce the DC to feed the inverter. This reduces the weight and size of the unit.

A typical modern inverter–generator produces 3kVA and weighs ~ 26 kg making it convenient for handling by one person.

=== Mid-size stationary engine–generator ===
[[Image:Big boy.jpg|thumb|Side view of a large [[Perkins Engines|Perkins]] diesel generator, manufactured by [[FG Wilson (Engineering) Ltd]]. This is a 100 [[Volt-ampere|kVA]] set]]
The mid-size stationary engine–generator pictured here is a 100 [[Volt-ampere|kVA]] set which produces 415 [[Volt|V]] at around 110 [[Ampere|A]]. It is powered by a 6.7-liter [[turbocharged]] [[Perkins Engines|Perkins]] [[Phaser 1000]] Series engine, and consumes approximately 27 liters of fuel an hour, on a 400-liter tank.  Diesel engines in the UK can run on [[red diesel]] and rotate at 1,500 or 3,000 rpm. This produces power at 50&nbsp;Hz, which is the frequency used in [[Europe]]. In regions where the frequency is 60&nbsp;Hz such as in North America, generators rotate at 1,800 rpm or another divisor of 3600. Diesel engine–generator sets operated at their peak efficiency point can produce between 3 and 4 kilowatt hours of electrical energy for each liter of diesel fuel consumed, with lower efficiency at partial loads.

=== Large scale generator sets ===
Many generators produce enough kilowatts to power anything from a business to a full-sized hospital.  These units are particularly useful in providing backup power solutions for companies which have serious [[Opportunity Cost|economic costs]] associated with a shutdown caused by an unplanned power outage.<ref>{{cite web|url=http://www.wpowerproducts.com/blog/ultimate-flexibility-for-emergencies-and-opportunities-a-resource-for-small-companies/|title=Ultimate Flexibility for Emergency Power Loss}}</ref>  For example, a hospital is in constant need of electricity, because several life-preserving medical devices run on electricity, like ventilators.

A very common use is a railway [[diesel electric locomotive]], some units having over {{convert|4,000|hp|kW|0|abbr=on}}.

Large generators are also used on board ships that utilize a [[diesel-electric]] powertrain. Voltages and frequencies may vary in different installations.

==Applications==
[[File:tie in panel.jpg|thumb|Generator tie-in panel 1200-amp outdoor enclosure]]
Engine–generators are used to provide electrical power in areas where utility (central station) electricity is unavailable, or where electricity is only needed temporarily. Small generators are sometimes used to provide electricity to power tools at construction sites. 
Trailer-mounted generators supply temporary installations of lighting, sound amplification systems, amusement rides, etc.  A wattage chart can be used to calculate the estimated power usage for different types of equipment to determine how many watts are necessary for a portable generator.<ref name="bestportablegenerators">{{cite web|title=What size generator do I need?|url=http://www.bestportablegenerators.org/size-generator-need/|website=bestportablegenerators.org|date=2 December 2016 }}</ref>
 
Trailer-mounted generators or mobile generators, diesel generators are also used for emergencies or backup where either a redundant system is required or no generator is on-site. To make the hookup faster and safer, a ''tie-in panel'' is frequently installed near the building switchgear that contains connectors such as camlocks. The tie-in panel may also contain a phase rotation indicator (for 3-phase systems) and a circuit breaker. Camlock connectors are rated for 400 amps up to 480-volt systems and used with 4/0 type W cable connecting to the generator. Tie-in panel designs are common between 200- and 3000-amp applications.

[[wikt:Standby|Standby]] electrical generators are permanently installed and used to immediately provide electricity to critical loads during temporary interruptions of the utility power supply. Hospitals, communications service installations, data processing centers, sewage pumping stations, and many other important facilities are equipped with standby power generators. Some standby power generators can automatically detect the loss of grid power, start the motor, run using fuel from a natural gas line, detect when grid power is restored, and then turn itself off—with no human interaction.<ref>
[http://www.smps.us/home-generators.html Home generators basics]
by L. Rozenblat 2008
</ref>

Privately owned generators are especially popular in areas where grid power is undependable or unavailable. Trailer-mounted generators can be towed to disaster areas where grid power has been temporarily disrupted.

== Safety ==
[[File:Generator_Carbon_Monoxide_Warning.jpg|thumb|right|Some generators include a warning stating "Using a generator indoors will kill you in minutes"<ref>{{cite web|url=http://www.cpsc.gov/en/Newsroom/News-Releases/2006/CPSC-Approves-NPR-Proposing-New-Warning-Label-for-Portable-Generators-/|title=CPSC Approves NPR Proposing New Warning Label for Portable Generators}}</ref>]]
Every year, incorrectly used portable generators result in deaths from [[carbon monoxide poisoning]].<ref name="CDC1" /><ref name="pmid17004412">{{cite journal |vauthors=Hampson NB, Stock AL |title=Storm-related carbon monoxide poisoning: lessons learned from recent epidemics |journal=Undersea & Hyperbaric Medicine |volume=33 |issue=4 |pages=257–63 |year=2006 |pmid=17004412 |url=http://archive.rubicon-foundation.org/5054 |archive-url=https://archive.today/20130415201710/http://archive.rubicon-foundation.org/5054 |url-status=usurped |archive-date=April 15, 2013 |access-date=2010-11-14}}</ref> A 5.5&nbsp;kW portable generator will generate the same amount of carbon monoxide as six cars, which can quickly build up to fatal levels if the generator has been placed indoors.<ref>{{cite web|url=https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5428a2.htm|title=Carbon Monoxide Poisoning from Hurricane-Associated Use of Portable Generators --- Florida, 2004}}</ref><ref>{{cite journal|url=http://currents.plos.org/disasters/article/carbon-monoxide-poisoning-and-flooding-changes-in-risk-before-during-and-after-flooding-require-appropriate-public-health-interventions/|title=Carbon Monoxide Poisoning and Flooding: Changes in Risk Before, During and After Flooding Require Appropriate Public Health Interventions|first1=Thomas|last1=Waite|first2=Virginia|last2=Murray|first3=David|last3=Baker|date=3 July 2014|journal= PLOS Currents Disasters|doi=10.1371/currents.dis.2b2eb9e15f9b982784938803584487f1|pmid=25045587|pmc=4096798|volume=6 |doi-access=free }}</ref> Using portable generators in garages, or near open windows or air conditioning vents can also result in carbon monoxide poisoning.<ref>{{cite journal | pmc=4559492 | pmid=26345640 | doi=10.1177/1524500413493426 | volume=19 | title=Storm-Related Carbon Monoxide Poisoning: An Investigation of Target Audience Knowledge and Risk Behaviors | year=2013 | journal=Soc Mark Q | pages=188–199 | vauthors=Damon SA, Poehlman JA, Rupert DJ, Williams PN| issue=3 }}</ref>

Additionally, it is important to prevent [[backfeeding]] when using a portable engine generator, which can harm utility workers or people in other buildings. Before turning on a diesel- or gasoline-powered generator, users should make sure that the main breaker is in the "off" position, to ensure that the electric current does not reverse.<ref>{{Cite web|title=Как подключить бензиновый генератор к сети дома|url=https://www.bigam.ru/stati/kak-podklyuchit-benzogenerator/|access-date=2021-03-22|website=Бигам|language=ru}}</ref><ref name="CDC1">{{cite web|title=Electrical Safety and Generators|url=http://emergency.cdc.gov/disasters/elecgenerators.asp|publisher=Centers for Disease Control and Prevention|access-date=3 April 2014}}</ref>

[[exhaust gas|Exhausting]] extremely hot flue gases from gen-sets can be done by factory-built positive pressure chimneys (certified to UL 103 test standard) or general utility schedule 40 black iron pipe. It is recommended to use insulation to reduce pipe skin temperature and reduce excessive heat gain into the mechanical room. There are also excessive pressure relief valves available to relieve the pressure from potential backfires and to maintain the integrity of the [[exhaust pipe]].<ref>{{cite web | url=http://danleygeneratorsnj.com/engine-generator-uses-safety/ | title=Engine Generator Uses and Safety | publisher=W. Danley Electrical Contracting | access-date=20 February 2015 | archive-url=https://web.archive.org/web/20150221013516/http://danleygeneratorsnj.com/engine-generator-uses-safety/ | archive-date=21 February 2015 | url-status=dead }}</ref>

== See also ==
{{div col|colwidth=30em}}
* [[Diesel electric locomotive]]
* [[Diesel electric multiple unit]]
* [[Diesel generator]]
* [[Electric generator]]
* [[Fuel cell]]
* [[Head end power]]
* [[Motor–generator]]
* [[Standby generator]]
* [[Stationary engine]]
{{div col end}}

== References ==
{{Reflist}}

== External links ==
{{Commons category|lcfirst=yes}}
* CDC: [http://emergency.cdc.gov/disasters/elecgenerators.asp Electrical Safety and Generators]

{{Authority control}}

[[Category:Electrical generators]]
[[Category:Engines]]