Slip ring, slip ring unit, electric machine, and wind turbine

A slip ring unit, comprising:

• a slip ring comprising an essentially cylindrical contact region defined by a radius and having a contact surface which faces in a radially outwards direction, said contact region having a recess in a region of the contact surface, said recess configured to have a projection extending on an inner side of the recess and/or being interrupted in a tangential direction, said contact region having an annular surface formed with an opening which communicates with the recess and is inclined towards an axial direction at an angle between 5 degrees to 45 degrees, and at least two insulating regions arranged axially adjacent to the contact region and each being defined by a radius, with the radius of the contact region being larger than the radius of the insulating region;
• an electrically conductive slip ring element for a rotary contacting transmission of electrical energy, said slip ring element transmitting the electrical energy to the contact region of the slip ring;
• and
• a stationary arrangement configured to guide and/or hold the electrically conductive slip ring element.