Abstract: To re-ignite efficiently an arc-furnace arc extending between an electrode and a material to be melt, a second energy supply is provided to maintain a plasma link between the electrode and the melting material when the arc-furnace arc is interrupted The electrode is supplied by a large current power supply including a large current conductor having a self inductance and being connected to the electrode. The second energy supply is an electrical power supply wherein a high frequency bypass impedance is provided in a supply path to the large current conductor at a distance from a capacitive circuit to allow a high frequency resonant circuit to be formed by the conductor section between the capacitive circuit and the bypass impedance without adversely affecting the large current power supply of the arc furnace.

Abstract: An earth cooled distribution transformer system and a method of cooling same and distributing electrical power to a plurality of consumer loads (31) is described. A distribution transformer (10 is provided with the primary (16) and secondary (17) windings encapsulated in a solid insulating material. The steel magnetic core (13) remains exposed and the transformer is buried in ground at a predetermined depth with the core (13) exposed whereby heat generated by the windings is dissipated into the earth through the exposed magnetic core. The high voltage supply cable (20) may be a buried cable or is at least partly buried as well as the power distribution cable (21), which feeds power to one or more consumer loads. The power distribution transformer (10) may be buried adjacent a manhole enclosure (12) with the primary and secondary winding power cables being connected to terminals (22-25) accessible in the manhole.

Abstract: The solid insulation transformer has a rectangular core covered with a compressible closed-cell foam to eliminate stress during curing of the cast dielectric material surrounding the core and during operation. Heat pipes are placed between the inner coil and the core to extract heat before the temperature builds up. For safety and to eliminate the need for a separate enclosure, an outer multi-layer casing having an incorporated grounded conductive layer is provided to cover the sides of the cast body. The outer casing prevents explosion if dielectric break down and arcing occur, and reduces the danger of electric shock.