Amongst other features, the annular generator is a key component in ENERCON’s gearless wind generator design. Combined with the rotor hub, it provides an almost frictionless flow of energy, while a smaller number of moving components assure minimal material wear. Unlike conventional fast-running generators, ENERCON’s annular generator is hardly subjected to mechanical wear, making it ideal for particularly heavy loads and a long service life. ENERCON’s annular generator is a low-speed synchronous generator with no direct grid coupling. Output voltage and frequency vary with the speed and are converted for output to the grid via a DC link and an inverter which allow for high speed variability.
Advantages of ENERCON’s annular generator:
- No gear
- Low wear due to slow machine rotation
- Low machine stress due to high level of speed variability
- Yield-optimised control
- High power quality
Stator and rotor
According to ENERCON’s service life requirements, the copper winding in the stator (the stationary part of the annular generator) known as closed, single-layer basket winding is produced in insulation class F (155 °C). It consists of individual round wires gathered in bundles and varnish insulated. At ENERCON, the copper winding is exclusively done manually. In spite of increasing automation in other manufacturing areas, in this case preference has been given to manual labour for good reason. It ensures that all materials used are fully inspected. Furthermore, a special work process allows continuous windings to be produced. Each wire strand is continuous from start to end.
Advantages of continuous winding:
- Eliminates errors when making electrical connections
- Maintains high-quality copper wire insulating system
- No contact resistance
- No weak points susceptible to corrosion or material fatigue
ENERCON’s annular generator features optimised temperature control. The hottest areas in the generator are constantly monitored by numerous temperature sensors. The sensors’ activation temperature is considerably lower than the temperature resistance of the insulating materials used in the generator. This prevents temperature overload.
In order to guarantee ENERCON’s high quality, all annular generators are manufactured in the company’s own production facilities. Superior quality materials are always used. Close collaboration with supplier companies has proven to be the most reliable way of providing maximum material quality. For example, the varnished copper wires are subjected to more testing than is specified in the standard and samples are archived, while surge voltage tests are performed on the pole shoes and chokes and then documented in the computer system.