A rotary sensor assembly, comprising a first sensor part with a plurality of position sensor segments, and a second sensor part with a grounded contact in contact with a position sensor segment. For acurrent incremental rotational position a contact is in contact with an un-powered current-position sensor segment, with the neighbor segments being in a powered state. When the contact is rotated toa powered next-position position sensor segment, the next-position sensor segment becomes a new current-position sensor segment. Electronic circuitry is adapted to detect that the new current-position sensor segment is grounded and that the first and second sensor parts thereby have been rotated one increment relative to each other, and subsequently change the state of the former current-positionsensor segment from un-powered to powered and the state of the new current-position sensor segment from powered to un-powered.