MRL / MRM: doubly-fed induction generators (DFIG) for wind turbines up to 8 MW
MRL and MRM are wound-rotor induction generators rated up to 8000 kW for geared wind turbines. They work on the doubly-fed (DFIG) scheme, where the stator is connected directly to the grid and the rotor is fed through slip rings from a frequency converter. The converter is rated for only part of the generator power, so the power electronics are cheaper.
- Type
- wound-rotor induction (DFIG)
- Output
- up to 8000 kW
- Voltage
- up to 1 kV
- Speed
- 1000–1800 rpm (converter in the rotor circuit, 0–1800 rpm)
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The DFIG scheme has long been proven in wind power. The generator operates reliably in variable-speed modes, and its maintenance procedures are familiar to service crews. The rated voltage of the MRL and MRM is up to 1 kV, the speed 1000–1800 rpm. The converter in the rotor circuit extends the regulation range to 0–1800 rpm. Only slip power passes through the slip rings, so the converter cabinet is noticeably smaller than the one a full-converter machine requires.
The two series differ in cooling. The MRL has a built-in air–air heat exchanger, the MRM is cooled through a built-in air–water heat exchanger. IEC frame sizes are 500–710, the mounting arrangement is IM B3, that is, a foot-mounted machine. The generator together with the slip ring assembly is protected to IP54, insulation class F or H. The machines are made to IEC 60034, and on request also to CSA C22.2 and UL 1004. Besides the onshore and offshore versions there are versions for hot and cold climates. The package includes common temperature and vibration sensors and encoders.
The manufacturer's wind generators are built on a platform principle. Within one power family, for example 3–5 MW, the bearing assemblies, cooling system and interfaces are common, and the output is changed by the winding. For a wind farm operator this means fewer spare part items and identical maintenance procedures, even if turbines of different output stand on the site. Rotors are balanced to ISO 21940-11 grade G2.5, and the coatings pass salt spray tests to ISO 9227. The design service life is up to 30 years.
The manufacturer's own motor plant produces generators for wind turbines of 2–8 MW, while across the group the range is wider, from 1.5 to 15 MW. Wind generators are also assembled at plants in Bosnia (2.0–6.8 MW) and India (1.5–7 MW). More than 20,000 of the manufacturer's wind generators operate worldwide. The manufacturer's generators are installed, among others, at the wind farms Dürnkrut, Sanganeri, Merdelou, Janneby and Jakoba Rippolder. When replacing a generator on an existing turbine, specify the output, voltage, speed range, cooling type and the seat dimensions in the nacelle, as well as the parameters of the existing rotor converter.
Technical specifications
| Type | wound-rotor induction (DFIG) |
|---|---|
| Output | up to 8000 kW |
| Voltage | up to 1 kV |
| Speed | 1000–1800 rpm (converter in the rotor circuit, 0–1800 rpm) |
| IEC frame size | 500–710 |
| Cooling | MRL: built-in air–air heat exchanger; MRM: air–water |
| Enclosure protection | up to IP54 (generator and slip ring system) |
| Insulation | F or H |
| Mounting | IM B3 |
| Standards | IEC 60034; CSA C22.2 and UL 1004 on request |
| Balancing | ISO 21940-11, G2.5 |
Request a price and lead time
MRL / MRM: doubly-fed induction generators (DFIG) for wind turbines up to 8 MW. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8501 64 00 00 |
|---|---|
| HS, 6 digits | 8501 64 |
| CN (EU) | 8501 64 00 |
| HTSUS (USA) | 8501 64 00 00 |
| China customs tariff | 8501 64 10 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
What output and voltage do the MRL and MRM generators have?
Up to 8000 kW at a voltage up to 1 kV. Operating speed 1000–1800 rpm, with a converter in the rotor circuit the regulation range is 0–1800 rpm.
How does the MRL differ from the MRM?
In the cooling system. The MRL has a built-in air–air heat exchanger, the MRM is cooled by an air–water heat exchanger.
To what standards are the generators made and balanced?
The generators are made to IEC 60034, on request to CSA C22.2 and UL 1004. Rotors are balanced to ISO 21940-11 grade G2.5, and coatings are tested in salt spray to ISO 9227.
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