Non-liquid immersed transformers and methods of measuring aging degree of the transformers' insulation are disclosed. The transformers comprise a solid insulation inside the conductive coil and one or more floating electrodes in the solid insulation. At least a part of the conductive coil and the one or more floating electrodes may form one or more capacitive elements, respectively. An electrical parameter, e.g. complex permittivity, of the capacitive element is measured and the aging degree is calculated as a function of the electrical parameter measurement.

A tap changer assembly of a dry-type transformer. The tap changer assembly includes a first molding including multiple taps, a semi-conductive coating applied to the first molding, a conductive shield provided overtop some of the semi-conductive coating, a grounding member comprising a ring of bosses interconnected by a grounding conductor connected to the conductive shield, a second molding applied over at least a portion of the conductive shield and the grounding conductor, the second molding forming a molded sealing surface, a conductive cover coupled to the ring of bosses; and a sealing member sealing a space between the molded sealing surface and the conductive cover. Dry-type transformers and methods of forming a tap changer assembly of a dry-type transformer are provided, as are numerous other aspects.

In some embodiments, a connection bar is provided for connecting multiple high voltage coils of a dry-type transformer along a top or bottom of the dry-type transformer. The connection bar includes (1) an electrically insulating body having a plurality of openings, each opening sized to receive at least one of high voltage terminals of the transformer; (2) an electrical connection pathway within the electrically insulating body configured to create a predetermined electrical connection between multiple high voltage coils of the transformer; (3) external connector terminals embedded within and extending from the electrically insulating body, the external connector terminals connected to the electrical connection pathway; and (4) a ground shield embedded within the electrically insulating body and configured to shield high voltage terminals of each high voltage coil of the transformer. Numerous other aspects are provided.

Dry-type transformers with insulating modules are disclosed. Example insulating modules include dielectric screens and supporting blocks. The supporting blocks support the dielectric screens over windings of the transformer. The dielectric screens have first substantially even portions configured to adapt in spaces defined by corresponding cylindrical barriers arranged between first and second windings of the transformers and second substantially even portions, transversal to the first portions and to the first windings of the transformers and extending outwards from the first portions and beyond the supporting blocks. The dielectric screens partly extend around a winding.

In a cost-effective and qualitatively better method for producing spacers for a winding unit of an electrical high-voltage device, at least two starting components are mixed together in a mixing chamber under vacuum to form a component mixture. The component mixture is transferred to an extrusion housing, likewise under vacuum, of an extruder in which a transport device is arranged and which is equipped with a mouthpiece delimiting an outlet opening. The extrudate exiting from the mouthpiece is cured by the addition of heat in a vacuum in order to obtain the spacers.

A reactor includes an outer peripheral iron core and at least three iron-core coils that contact or are connected to an inner surface of the outer peripheral iron core. Each of the iron-core coils includes iron cores and coils wound onto the iron cores. The reactor further includes an external cooling unit disposed outside the outer peripheral iron core, to cool the outer peripheral iron core.

A reactor includes an outer peripheral iron core and at least three iron-core coils that contact or are connected to an inner surface of the outer peripheral iron core. Each of the iron-core coils includes iron cores and coils wound onto the iron cores. The reactor further includes an external cooling unit disposed outside the outer peripheral iron core, to cool the outer peripheral iron core.

A dry type cast-coil transformer having a voltage rating of 1 Kv and above, including: at least one coil with a plurality of conductor turns; a cast comprising a polymeric resin, encompassing the coil and having a cast surface; a ferromagnetic core on which the coil with the encompassing cast is mounted; an insulated cable termination connected to the coil, wherein the connection point between the insulated cable termination and the coil is within the cast, and wherein a flexible portion of the insulated cable termination further extends from the cast surface outwards and comprises a plurality of metal wires.

An air-cooled dry-type transformer includes: a core provided with a branch; a winding body arranged about the branch; a cooling channel extending in a direction of a longitudinal axis of the winding body, the cooling channel being arranged between an inner part of the winding body and an outer part of the winding body, the cooling channel having openings at both ends and a substantially ring-shaped cross section with a round, oval, or polygonal basic shape; and at least one ring ventilator comprising a ring and a blower. The blower suctions air and blows the air from the ring along a longitudinal axis of the ring, thereby generating an air flow. The at least one ring ventilator is dimensioned and mounted such that the air flow generates a cool air flow in the cooling channel.

In some embodiments, a shielded coil assembly is provided that includes (1) a coil having an outer surface, an inner surface, an upper end surface and a lower end surface and a first insulating material formed over the outer surface, inner surface, upper end surface and lower end surface of the coil; and (2) a conductive shield comprising a conductive paint applied along the first insulating material so that the conductive paint extends over at least a portion of each of the outer surface, inner surface, upper end surface, and lower end surface of the coil. In one or more embodiments, a dry-type transformer may be formed using the shielded coil assembly. Numerous other embodiments are provided.