Asynchronous Generator System

asynchronous generator

The asynchronous machine is known for more than 100 years. Experience showed that without any special measures the machine can supply electrical energy into the mains when it is driven mechanically beyond its no-load speed.

Additionally it is known what to consider for the electrical design obtaining optimum results for generator operation as well.

Asynchronous Generator Circle Diagram

However the use of asynchronous machines as generators could be found as strongly increasing recently. This depends on various factors, e.g.:

• As per the "Energy  in speisegesetz" (EEG – Law that regulates feeding of renewable energy into the power supply system) anyone is allowed to supply electrical energy into the three-phase system. Also in case of small plants the power supplying companies are obliged to take the power at a firm price.
• Meanwhile our three-phase systems are linked to such an extent that there is the possibility of power supply even in remote areas.
• The supply systems are of such a high capacity that even for large-sized asynchronous generators the necessary reactive power (cf. 2.4.) is available and the mains connection (cf. 4) is mostly possible without special measures.
• The reliability and the simple control of asynchronous generators meet very much the tendency to an "Attendantless, full automatic small power plant". Plants between some kW and 1500 kW belong to this category today The "Alternative Energy" is gaining more importance. Asynchronous generators are for instance also successfully used in wind power plants.

Asynchronous Generator Table

When the machine is dimensioned adequately, e.g. accepting the surcharge for a copper cage in the rotor, the efficiency is very high, even at partial load operation (cf. 5.1). There are practically no wear and maintenance parts except the bearings. Also special requests can be fulfilled without lot of expenditure: e.g. speed steps by conventional polechanging, optimum yield of energy in the whole power range (cf. 5.3).

The current status of inverter technology even offers the possibility of an infinitely variable speed. As coming near to the "standardized industrial motor" all constructional special requests being usual there (for instance a selection of the mountings, enclosures and cooling systems of the IEC series) are no problem and available by basic features from all leading manufacturers.