The slip ring and the rotor brushes are key elements of the generator. They make the connection between the rotor coils and the rotor cables. These parts work at a high-speed level, an average speed of 1250 RPM is synchronous for the 50Hz grid. However this can vary depending on the converter manufacturer.

A slight deformation of the slip ring at this speed can have implications for the generation and cause damage, not only to the generator, but also to the converter, cables and busbars. The problem comes from an electrical arc between the carbon brushes and the slip ring.

The carbon brushes need to be perfectly in contact with the slip ring tracks.  If they aren’t, the current carried by the carbon brushes creates electrical arcs, caused by the carbon jumping during speed rotation, due to deformation of the slip ring. This repeated arcing causes overheating of the cylinder and will increase its deformation and, ultimately, failure of the generator.

Even if the generator is normally inspected every year by the manufacturers, it does not prevent the problem from occurring between two maintenance cycles. Greensolver’s advice is to check with the manufacturer that there are regular slip ring inspections, and we can help you do this as part of an End of Warranty Inspection or Due Diligence inspection.

By Carla Vico – Operations Director