Transformer core and transformer

A transformer, comprising:

• a transformer core comprising:
• a first yoke,
• a second yoke,
• a column having a column main axis and extending between the first yoke and the second yoke, and
• an elongate clamping structure comprising an elongate rigid member having a rigid member main axis,
• the column including an elongate opening having an opening main axis which is oriented transversal with respect to the column main axis,
• the rigid member positioned within the elongate opening such that the rigid member main axis is oriented parallel to the opening main axis,
• the elongate clamping structure comprising a first end portion and an opposing second end portion, wherein the first and second end portions are configured to compress a portion of the column which surrounds the clamping structure,
• the first end portion and/or the second end portion of the elongate clamping structure comprising a fixing member having a conical shaped head portion,
• the transformer core further comprising at least one washer positioned around the conical shaped head portion of the fixing member,
• the elongate clamping structure further comprising an insulation tube which is positioned between the rigid member and an inner surface of the elongate opening and configured to effectuate an isolation between the rigid member and the column,
• the washer formed as a part of the insulation tube;
• and
• a winding wound around the column.