Transformer, power conversion device, product group of transformer, and manufacturing method for transformer

A transformer comprising:

• a core portion for forming a magnetic circuit;
• a primary winding and a secondary winding wound at the core portion;
• and
• a first connection portion having a plurality of first conductive parts arranged with an insulation interval therebetween, wherein
• one or both of the primary winding and the secondary winding are divided into a plurality of division windings, and each of the plurality of division windings of the at least one divided winding has a wound part wound at the core portion, and two extending members extending from both ends of the wound part,
• the first connection portion is connected to one of the two extending members of each of the plurality of division windings of the at least one divided winding,
• when the first connection portion has two of the first conductive parts, each of the two first conductive parts is an external connection part to be connected to outside and is a mutual connection part which mutually connects two or more of the extending members, and
• when the first connection portion has three or more of the first conductive parts, each of two specific ones of the first conductive parts is the external connection part, or is the external connection part and is the mutual connection part, and each of one or more non-specific ones of the first conductive parts other than the two specific first conductive parts is the mutual connection part.