Single-phase generator

Elementary generator is an example of single-phase generators with two poles
Armature of revolving armature single-phase generator with 4 windings and its output sine wave.
Single phase generator with four poles
Diagram of revolving field single-phase generator with two poles
Diagram of revolving field single-phase generator with four poles
In-conduit hydro turbine with single-phase generator at St. Louis Municipal Electric Power Plant in 1902
Pelton wheel on the left connected to single-phase generator on the right at Walchensee hydro station.
Single-phase generator driven by steam engine at St. Louis Municipal Electric Power Plant in 1902 (right)
Neckarwestheim Nuclear Power Plant

Alternating current electrical generator that produces a single, continuously alternating voltage.

- Single-phase generator

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Single-phase electric power

Distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison.

A single-phase polemount stepdown transformer in Canada. One supply phase (phase-to-neutral) from the utility is converted to split-phase for the customers.

Single-phase power may be used for electric railways; the largest single-phase generator in the world, at Neckarwestheim Nuclear Power Plant, supplied a railway system on a dedicated traction power network.


Combination of an electrical generator and an engine mounted together to form a single piece of equipment.

Cart-mounted engine–generator being used at a construction site
A Cummins Onan transfer switch
MAN diesel stationary engine and generator, now on outdoor museum display
Side view of a large Perkins diesel generator, manufactured by FG Wilson (Engineering) Ltd. This is a 100 kVA set
Generator tie-in panel 1200-amp outdoor enclosure
Some generators include a warning stating "Using a generator indoors will kill you in minutes"

Most of the portable units available are single-phase generators and most of the three-phase generators manufactured are large industrial type generators.

Small wind turbine

Small wind turbines, also known as micro wind turbines, are used for microgeneration of electricity, as opposed to large commercial wind turbines, such as those found in wind farms.

Diagram of a small wind turbine and repeller.
A 1 kW micro windmill installed in the suburbs of Lahore, Pakistan.
Small wind turbine power output
Ground mounted small wind turbines are typically supported by four guy-wire, and a gin pole used to raise and lower the tower. Full mounting sets called "tower kits" are available.
Wind turbines small enough to be held by a single steel pipe are often secured with scaffold base plate mounted to a concrete foundation. A hinged design allows easy lowering for maintenance.
A high level wiring diagram for an off-grid hybrid wind/PV system.
A three phase rectifier being used on a rooftop mounted urban wind turbine.
Resistors being used as a diversion load which protect the turbine in the event of strong winds.
A small-scale wind tower in rural Indiana, United States
Hybrid system, 2400W windturbines, 4000W solar modules, island Žirje, Croatia

The generators for small wind turbines are usually three-phase alternating current generators and the trend is to use the induction type, although some models utilize single-phase generators or direct current output.

15 kV AC railway electrification

Europe rail electrification en.svg in Europe:

A pylon of a single phase AC 110 kV-powerline near Bartholomä in Germany. Lines of these type are used in Germany to supply electric railways with single phase AC at 16.7 hertz. In the substations of the railway, transformers are used to step it down to 15 kV.
Single-phase (two-wire) lines coming out of a converter plant

The converters consist of a three-phase synchronous motor and a single-phase synchronous generator.

Walchensee Hydroelectric Power Station

Hydroelectric power station in Bavaria, Germany.

Overview of the turbines
Changing of the Pelton wheels
The six penstocks
The six penstocks

Through six, 450 m ducts connecting the two natural lakes, the water flows to the hydro-electric plant's four Pelton water turbines with single-phase generators, and four Francis water turbines with three-phase generators, and then exits into the Kochelsee.

Amtrak's 25 Hz traction power system

Traction power grid operated by Amtrak along the southern portion of its Northeast Corridor : the 226.6 route miles (362 km) between Washington, D.C. and New York City and the 104 route miles (167 km) between Philadelphia and Harrisburg, Pennsylvania.

An Amtrak HHP-8 under 25 Hz wire at Odenton station
Old substation built for the 1915 electrification project at Bryn Mawr, Pennsylvania. Outdoor yard is an addition.
West Philadelphia substation 1915
The Safe Harbor Dam generates 25 Hz railroad power via two turbines in the east end of the turbine hall and an M-G set outside against the Dam face.
Waterside Power station in Manhattan, New York
Long Island City Power Plant under construction in New York in 1905
The Pepco Benning Road power station in Washington, D.C., supplied 25 MVA of 25 Hz power via a rotary frequency changer in the hall nearest the Metro tracks from 1935 until 1986.
A picture of one of the 1916 Radnor Synchronous Condensers from Electrical World
Frazer substation on the Philadelphia to Harrisburg Main Line
Old substation remote control panel at Paoli interlocking tower
A one-line diagram of the 1930 era substation at Bowie, MD
The large substation at the Safe Harbor dam is one of the minority that steps-up 25 Hz power to 138 kV for long distance transmission.
One-line diagram of Zoo Sub 9, circa 1997, on the Load Dispatcher mimic board in Philadelphia
The Power Dispatcher's view of substation 43 (New York City Penn Station)
The Load Dispatcher's Mimic Board at 30th Street Station in Philadelphia, Pennsylvania, circa 1996. The entire 138 kV transmission system is represented on this panel.
The four utility-owned 138 kV circuits from Safe Harbor (Pennsylvania) to Perryville (Maryland).
Catenary support with 6.9 kV, 100 Hz transformer for signal power
Catenary supports near Odenton, Maryland. Three-conductor 60 Hz utility lines enter from the left and are carried in either direction along the line. The remainder of the high voltages lines are 25 Hz.
Ivy City Substation 25 under construction in Washington, D.C., in 2010

Safe Harbor Dam, PA – The Safe Harbor Dam has two 28 MW, single phase, turbines dedicated to 25 Hz power generation. A 25 MW bi-directional motor generator type frequency converter is also installed. The total 25 Hz capacity of the dam is 81 MW. Power from Safe Harbor is transmitted via the Conestoga substation to Royalton, Pennsylvania, Parkesburg, Pennsylvania (two circuits), and Perryville, Maryland (four circuits) where it is fed into the lineside 138 kV network.

Safe Harbor Dam

Concrete gravity dam, with an associated hydroelectric power station, on the lower Susquehanna River.

Units 1 and 2 are Kaplan turbines connected to single-phase generators to produce 25 Hz single-phase electric power for railroad use by Amtrak and SEPTA, but also can be connected to a motor-generator to convert any spare 25 Hz power to 60 Hz. The rest of the units generate 60 Hz, three-phase power.

Ames Hydroelectric Generating Plant

One of the first commercial system to produce and transmit alternating current (AC) electricity for industrial use and one of the first AC hydro-electric plants ever constructed.

Workmen with one of the two Westinghouse alternators used in the original 1891 Ames Hydroelectric AC power installation
Interior view, 1895 Ames powerhouse
Overall view of Ames plant, early 20th century
2010 exterior view of Ames Power Station, built 1905.

The system consisted of two identical 100-hp Westinghouse single-phase alternators (the largest the company made at the time).

Neckarwestheim Nuclear Power Plant

Nuclear power plant in Neckarwestheim, Germany, sometimes abbreviated GKN , operated by EnBW Kernkraft GmbH, a subsidiary of EnBW.

The Containment buildings of the two Neckarwestheim-units
The Unit 1 of the Neckarwestheim Nuclear Power Plant (right) and the cooling tower of Unit 2 (left)
Traction Current Inverter under construction
The cell cooling towers from
Unit 1
The "hybrid" cooling tower for the plant
Unit 1
The Neckarwestheim Nuclear Power Plant photographed from the castle "Liebenstein" near Neckarwestheim
The nuclear power plant in 1979: only Unit 1 was operational, Unit 2 was under construction

The traction current generator is the world's largest single-phase AC generators.

Polyphase coil

Polyphase coils are electromagnetic coils connected together in a polyphase system such as a generator or motor.

The magnetic field lines ( green ) of a current-carrying loop of wire pass through the center of the loop, concentrating the field there

Compared to single-phase motors and generators, polyphase motors are simpler, because they do not require external circuitry (using capacitors and inductors) to produce a starting torque.