A medical apparatus (600) including: a magnetic resonance imaging system (602) a medical device (634) and a slip ring assembly (400 500) for supplying electrical power to the medical device. The slip ring assembly includes: a cylindrical body (100) a rotating member (402) for rotating the medical device a first cylindrical conductor attached to the cylindrical body a second cylindrical conductor (108) a first set of conductive elements (112 712) connected to the second cylindrical conductor and a brush assembly (406) comprising a first brush (302) and a second brush (304). The first brush is operable to contact the first cylindrical conductor. The second brush is operable to contact the set of conductive elements. The first and second cylindrical conductive elements overlap at least partially. The second cylindrical conductor is connected to the cylindrical body. The first cylindrical conductor and the second cylindrical conductors are electrically isolated.
