On-load tap changer with positioning device and method for assembling an on-load tap changer

An on-load tap changer comprising:

• a static unit comprising fixed contacts for connection to taps at a transformer winding,
• a dynamic unit comprising at least one movable contact for selectively contacting one of the fixed contacts during operation of the transformer,
• and comprising a rotational positioning device for adjusting the rotational position of the dynamic unit relative to the static unit during at least one of assembly or disassembly of the tap changer to engage or disengage the movable contacts to or from the fixed contacts,
• wherein the dynamic unit comprises first teeth and the static unit comprises a spur wheel comprising second teeth, the first teeth and the second teeth interacting with each other, wherein the rotational positioning device comprises an adjustment member operable by a user for rotating the spur wheel,
• wherein the rotational positioning device comprises a first stop position, in which further rotational adjustment in one rotational direction is prevented, wherein in the first stop position the movable contacts are fully engaged with the fixed contacts and wherein the rotational positioning device comprises a second stop position, in which further rotational adjustment in a second rotational direction is prevented, the second rotational direction being opposite to the first rotational direction, wherein in the second stop position the movable contacts are fully disengaged from the fixed contacts.