A reactor includes a magnetic core and a plurality of coils disposed adjacent to each other and electrically connected to each other. The plurality of coils includes an intermediate coil inducing a magnetic flux which does not interlink with an end of the magnetic core, and magnetic paths forming at least two closed magnetic paths run through a portion inside the intermediate coil.

A non-liquid immersed transformer includes a magnetic core and a coil winding forming a plurality of winding turns around the magnetic core; a cooling system and a first conductive connector. The cooling system includes a cooling pipe for the flow of a cooling fluid, the cooling pipe extending along the coil winding and including a first point adjacent to a turn of the coil winding, and a second point adjacent to another turn of the coil winding. The conductive connector is arranged at one of the first and second points, to electrically connect an inner side of the cooling pipe with a turn of the coil winding.

A non-liquid immersed transformer includes a magnetic core and a coil winding forming a plurality of winding turns around the magnetic core; a cooling system and a first conductive connector. The cooling system includes a cooling pipe for the flow of a cooling fluid, the cooling pipe extending along the coil winding and including a first point adjacent to a turn of the coil winding, and a second point adjacent to another turn of the coil winding. The conductive connector is arranged at one of the first and second points, to electrically connect an inner side of the cooling pipe with a turn of the coil winding.

A power electronic transformer, including at least one first voltage unit including first voltage power electronics building blocks, at least one second voltage unit including second voltage power electronics building blocks, the first voltage being lower than the second voltage, and a two-phase cooling unit including a two-phase cooling medium for cooling the at least one second voltage unit. The two-phase cooling unit allows for an improved overall system performance of the transformer regarding costs, effort for maintenance, risk of malfunction or failure, and weight and footprint of the construction.

A power electronic transformer, including at least one first voltage unit including first voltage power electronics building blocks, at least one second voltage unit including second voltage power electronics building blocks, the first voltage being lower than the second voltage, and a two-phase cooling unit including a two-phase cooling medium for cooling the at least one second voltage unit. The two-phase cooling unit allows for an improved overall system performance of the transformer regarding costs, effort for maintenance, risk of malfunction or failure, and weight and footprint of the construction.