Question 1

What transformer is used in a wind turbine?

Accepted Answer

Wind turbines use a generator step-up (GSU) transformer to raise the generator's low-voltage output to the wind farm's medium-voltage collector system. For nacelle-mounted applications, dry-type cast-resin transformers are preferred due to their fire safety and compact form factor. At the substation, a high-voltage main transformer steps the collector voltage up to transmission level (110 kV or 220 kV) for grid interconnection.

Question 2

What is a GSU transformer in a wind farm?

Accepted Answer

A GSU (Generator Step-Up) transformer is the unit that steps the wind turbine generator's output voltage up to the wind farm's medium-voltage collector system voltage. It sits at or near the base of each turbine tower (or inside the nacelle for smaller turbines) and must be designed for the cyclic loading profile of wind generation — variable output, frequent start/stop cycles, and outdoor or nacelle exposure.

Question 3

Why are dry-type transformers used in wind turbine nacelles?

Accepted Answer

Nacelle-mounted transformers must be compact, lightweight, and fire-safe — a critical requirement given the difficulty of fighting a fire at the top of a turbine tower. Cast-resin dry-type transformers contain no flammable insulating oil, are self-extinguishing, and can be designed to fit the nacelle's dimensional constraints. They also require no oil containment and minimal maintenance access, which is important given the height and remote location of nacelle equipment.

Question 4

What standards apply to wind farm transformers?

Accepted Answer

Wind farm transformers are typically built to IEC 60076 (power transformers) and IEC 60076-11 (dry-type transformers) for international projects, or ANSI/IEEE C57.12 series for North American projects. GSU transformers for wind applications may also reference IEC 61400-4 (wind turbine design requirements for gearboxes, which includes transformer interfaces). Grid interconnection follows IEEE 1547 or local grid codes.

Wind Farm Transformers | Turbine & Substation | Seatrust