Abstract: An autotransformer having the same polarity impedance, series and tertiary windings as defined by an equivalent three-terminal network of said autotransformer. Autotransformers are often protected against phase-to-ground faults by ground fault relays and such devices require this type of impedance relationship for proper operation; especially during phase-to-ground fault conditions.

Abstract: A probe of the mutual inductance type with a linear response which is independent of temperature comprises a rigid support, two insulated cables disposed in interengaged relation and wound on the support, means for supplying one of the cables C.sub.1 with alternating current having constant amplitude and frequency, means for measuring the voltage between the two extremities of the second cable C.sub.2. A single resistor R is placed between the extremities of the cable C.sub.2, the resistance value of the resistor and the value of the frequency f being determined so as to ensure that the variations in voltage measured between the extremities of the cable C.sub.2 are reduced to zero in respect of any given level of liquid outside the probe.

Abstract: Distribution transformer having inner and outer low-voltage winding sections and a high-voltage winding section disposed therebetween. Insulation structures separate the various winding sections and include a relatively small thickness of solid insulating material and a liquid dielectric duct. Some of the solid insulating material is axially extended to increase the creep resistance of the winding. The insulation structures are also void of any metallic electrostatic shield or any other member which would hamper adequate processing of the insulation structure during the construction of the transformer.

Abstract: A measuring coil comprises two windings, each being formed by winding simultaneously two insulated wires having the same size, the two wires of each winding extending side by side. The windings formed by the single turns of the wires in each winding are interconnected in such a way that the magnetic effects are additive in the wires of a first of said windings and subtractive in the wires of the second winding. The single turns of the first wire in each of the two windings form the measuring coil to be fed by an alternating current and the single turns of the second wire in each of said two windings form both a sensing element for measuring the temperature of the measuring coil and/or a heating element to be fed by an adjustable direct current for maintaining the coil temperature at a predetermined value with a high accuracy.

Abstract: An improved medium power transformer of the type having a secondary winding suitable for rigid connection with an inductor through which coolant flows, the secondary winding conductors overlapping in the area of the secondary connections and having two layers of primary windings flanking the secondary winding, core elements enclosing the hollow winding conductors except in the area of overlap. To minimize the thickness of the transformer, a cooling line having two separated portions is disposed in overlap along the periphery of the secondary winding in one layer.