Study on V-I Characteristic in Natural Graphite Brush vs Steel Slip Ring System

Sliding contact systems are widely used as a method of exchanging electrical power between static and moving components. In the brush slip-ring system using copper based materials, several studies have reported that voltage-saturation characteristics caused by oxide film at V-I characteristic are obtained. However, it is considered that the reliability and maintainability of machines are influenced by the insufficient knowledge about the V-I characteristic of steel slip-rings in synchronous generators. Therefore, in order to guarantee reliable and stable operation of the generators, it is necessary to elucidate the V-I characteristic, the imbalance of the current sharing, the arc generation and the wear characteristics at a high sliding speed.Experimental equipment for clarifying various characteristics of steel slip-ring system was designed with reference to actual synchronous generator. As a result, peripheral speed and current value equivalent to the actual machine were realized, and the V-I characteristic can be acquired. In addition, when comparing V-I characteristic of copper based and steel slip-rings, it can be made clear that the voltage saturation characteristics of the steel slip-ring are quite different from that of the copper based ring.