A turbo generator is an electric generator connected to the shaft of a steam turbine or

gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...

for the generation of electric power. Large

steam-powered A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be tr ...

turbo generators provide the majority of the world's electricity and are also used by steam-powered turbo-electric ships. Small turbo-generators driven by

s are often used as

auxiliary power unit An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115& ...

s (APU, mainly for

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...

History

The first turbo-generators were electric generators powered by

water turbines A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now, th ...

. The first Hungarian water turbine was designed by the engineers of the

Ganz Works The Ganz Works or Ganz ( or , ''Ganz companies'', formerly ''Ganz and Partner Iron Mill and Machine Factory'') was a group of companies operating between 1845 and 1949 in Budapest, Hungary. It was named after Ábrahám Ganz, the founder and the ...

in 1866; industrial-scale production with dynamo generators started only in 1883. Engineer

Charles Algernon Parsons Sir Charles Algernon Parsons, (13 June 1854 – 11 February 1931) was an Anglo-Irish engineer, best known for his invention of the compound steam turbine, and as the eponym of C. A. Parsons and Company. He worked as an engineer on d ...

demonstrated a DC steam-powered turbo generator using a

dynamo "Dynamo Electric Machine" (end view, partly section, ) A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundati ...

in 1887, and by 1901 had supplied the first large industrial AC turbo generator of megawatt power to a plant in Eberfeld, Germany. Turbo generators were also used on steam locomotives as a power source for coach lighting and water pumps for heating systems.

Construction features

Turbo generators are used for high shaft rotational speeds, typical of steam and gas turbines. The

rotor Rotor may refer to: Science and technology Engineering * Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator *Helicopter rotor, the rotary wing(s) of a rotorcraft ...

of a turbo generator is a non-salient pole type usually with two poles. The normal speed of a turbo generator is 1500 or 3000 rpm with four or two poles at 50 Hz (1800 or 3600 rpm with four or two poles at 60 Hz). The rotating parts of a turbo generator are subjected to high mechanical stresses because of the high operation speed. To make the rotor mechanically resistant in large turbo-alternators, the rotor is normally forged from solid steel and alloys like chromium-nickel-steel or chromium-nickel-molybdenum are used. The overhang of windings at the periphery will be secured by steel retaining rings. Heavy non-magnetic metal wedges on top of the slots hold the field windings against centrifugal forces. Hard composition insulating materials, like mica and asbestos, are normally used in the slots of rotor. These material can withstand high temperatures and high crushing forces. The stator of large turbo generators may be built of two or more parts while in smaller turbo-generators it is built up in one complete piece.

Hydrogen-cooled turbo generator

Based on the air-cooled turbo generator, gaseous

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

first went into service as the

coolant A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosi ...

in a

hydrogen-cooled turbo generator A hydrogen-cooled turbo generator is a turbo generator with gaseous hydrogen as a coolant. Hydrogen-cooled turbo generators are designed to provide a low- drag atmosphere and cooling for single-shaft and combined-cycle applications in combination ...

in October 1937, at the

Dayton Power & Light DP&L Inc. is a subsidiary of AES Corporation. Through its subsidiaries The Dayton Power and Light Company and DPL Energy Resources, DP&L sells to, and generates electricity for, a customer base of over 500,000 people within a area of West Central ...

Co. in

Dayton, Ohio Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater D ...

. Hydrogen is used as the coolant in the rotor and sometimes the stator, allowing an increase in specific utilization and a 99.0% efficiency. Because of the high

thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

, high

specific heat In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...

and low

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of hydrogen gas, this is the most common type in its field today. The hydrogen can be manufactured on-site by electrolysis. The generator is hermetically sealed to prevent escape of the hydrogen gas. The absence of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

in the atmosphere within significantly reduces the damage of the windings' insulation by eventual

corona discharge A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor (material), conductor carrying a high voltage. It represents a local region where the air (or other fluid) has undergone e ...

s. The hydrogen gas is circulated within the rotor enclosure, and cooled by a gas-to-water

heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...

Notes

References

External links

Small Turbo-generator for DG & Hybrids
{{DEFAULTSORT:Turbo Generator Electrical generators Turbines