Slip ring assembly is typically a graphite or precious metal brushes. As the ring rotates, current or signal transduction through the fixed brush with metal rings to connect. Additional ring brush assemblies are stacked along the rotation axis of a plurality of circuits.

In pitch slip rings, new design trends are on at least two fronts, Firstly, as turbine designs increase in power output and size, the demand on the pitch slip ring is higher power transfer; Secondly, data handling and signal demands are increasing to provide additional condition monitoring in the hub, It is critical for the contact technology.

Another trend is toward notion control of the pitch, it would include hub controls, pitch-drive motors, power back-up, blade monitoring, and the slip ring to transfer the power and control signals through the rotary interface.

On the other hand, the wind-turbine service market is growing quickly as the turbine population ages and asset owners are looking for ways to control maintenance costs. Products should be able to replace slip rings in older turbines with long-life, high-reliability designs to provide pitch slip rings that can operate for years without maintenance.

Many designs in use today require periodic maintenance to clean away wear debris, flush out oil and dirt, and relubricate. It is very frequent to change the slip ring, so it is essential to design a new slip ring which can be a long life and less maintenance.

The high-reliability request has encouraged some companies to research non-contacting slip rings. One is an inductively coupled power transfer device. Inductive-power transfer applies the principle of electromagnetic inductance. In fact, now it have a company have produced it and also went into slip ring market.

For wireless power, it is not reliable as the transimission distance increase,so it need us to improve it and hope one day this new technology can be used by all of slip ring industry.