Three-phase generator
The three-phase generator is a special form of the electrical generator , which induces three independent alternating voltages in the strands of its stator winding offset by 120 ° (see internal pole machine ). The three alternating voltages, i.e. the three-phase alternating voltage , have the same frequency , amplitude and a phase shift of 120 ° to one another. The three strands of the stator winding form a linked system. They are either connected in a star or a triangle . The star connection is used when a center conductor (neutral conductor) is required. The inventor of the three-phase generator was Friedrich August Haselwander .
commitment
Typical representatives of three-phase generators are the three-phase synchronous generator and the three-phase asynchronous generator . Three-phase synchronous generators are of great importance in large-scale power generation. They are used, for example, in steam power plants or hydropower plants . For the Finnish nuclear power plant Olkiluoto , Siemens manufactured what is currently (as of 2010) the largest generator, a three-phase synchronous generator with a nominal apparent power of 1,992 MVA. Three-phase asynchronous generators are used in the lower power range, for example in wind turbines and emergency power generators .
Induced tension
From and it follows for the induction voltage (induced string open circuit voltage ):
wherein the speed , the circular constant , the rotor diameter , the rotor length , the rotational frequency , the number of pole pairs , the magnetic flux density , the conductor (an) number and the number of coil turns is. The product has to be doubled because with 3-phase alternating current (three-phase current) in the generator there are forward and return conductors (through which current flows) .
See also
literature
- Rainer Ose: Electrical engineering for engineers. 4th edition. Carl Hanser Fachbuchverlag, Munich 2008, ISBN 3-446-41196-8 .