Engine-generator

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MAN diesel engine and generator, now on outdoor museum display

An engine-generator is the combination of an electrical generator and an engine (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.

Components

In addition to the engine and generator, engine-generators generally include a fuel supply, a constant engine speed regulator (governor) and a generator voltage regulator, cooling and exhaust systems, and lubrication system. Units larger than about 1 kW rating often have a battery and electric starter motor; very large units may start with compressed air 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.

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, as pictured below, that can supply several thousand watts and stationary or trailer-mounted units that can supply over a million watts. Regardless of the size, generators may run on gasoline, diesel, natural gas, propane, bio-diesel, sewage gas or hydrogen. Most of the smaller units are usually 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 operation).

Some engine-generators use a turbine as the engine, such as the industrial gas turbines used in peaking power plants and the microturbines used in some hybrid electric buses.

Other engine-generators use a steam engine, such as most coal-powered fossil-fuel power plants.

Other engine-generators use a reciprocating engine.

The generator voltage (volts), frequency (Hz) and power (watts) ratings are selected to suit the load that will be connected.

Engine driven generators fueled on natural gas fuel often form the heart of small scale less than 1,000 kW combined heat and power installations.

There are only a few portable three-phase generator models available in the US. Most of the portable units available are single phase power only 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.

Portable engine-generators may require an external power conditioner to safely operate some types of electronic equipment. Small portable generators may use an 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.

Mid-size stationary engine-generator

The mid-size stationary engine-generator pictured here is a 100 kVA set which produces 415 V at around 110 A. It is powered by a 6.7 liter turbocharged 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 a frequency of 50 Hz, which is the frequency used in the UK. In areas where the power frequency is 60 Hz (United States), 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 kilowatthours of electrical energy for each liter of diesel fuel consumed, with lower efficiency at part load.

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  Engine - generator for a radio station (Dubendorf museum of the military aviation). The generator worked only when sending the radio signal (the receiver could operate on the battery power)

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  Side view of a large Perkins diesel generator, manufactured by FG Wilson Engineering Ltd. This is a 100 kVA set.

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  Control panel on ~100 kVA Aggreko generator set

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  Emergency power generator in a drinking water pumping station. Brons engine with Heemaf generator.

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  Another generator, powered by fossil fuels and used at a construction site.

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  An engine-generator.

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  Image of a common engine-generator

Application

Engine-generators are used to supply electrical power in places where utility (central station) power is not available, or where power is needed only temporarily. Small generators are sometimes used to supply power tools at construction sites. Trailer-mounted generators supply power for temporary installations of lighting, sound amplification systems, amusement rides etc.

Standby power generators are permanently installed and kept ready to supply power 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.

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.

References

cs:Motorgenerátor se spalovacím motorem sv:Aggregat