A method for obtaining a relation between a winding state and a leakage reactance parameter of a transformer by using simulation software is provided. The method includes: establishing a simulation transformer based on a size of a physical transformer; setting parameters of the simulation transformer, setting a winding of the simulation transformer in a predetermined winding state; obtaining a predetermined number of values of a leakage reactance parameter of the simulation transformer in the winding state; and performing statistics on all the values to obtain a value range of the leakage reactance parameter in a case that the winding is in the winding state. The value range is used as a value range of a leakage reactance parameter of the physical transformer in a case that a winding of the physical transformer is in the winding state.

A transformer assembly for electric grids including: an electric transformer including a magnetic core, a first side including one or more first windings enchained with said magnetic core and adapted to be electrically connected to a first grid section and a second side including one or more second windings enchained with said magnetic core and adapted to be electrically connected to a second grid section; a tap changer operatively associated with said electric transformer to vary the number of turns enchained with said magnetic core for said first windings; a control unit to: acquire input data indicative of an electrical connectivity condition of said second grid section with said second windings; determine whether said transformer is in a load condition or in a no-load condition; and, in a no-load condition, command said tap changer to set a maximum available number of turns for said first windings.

A transformer arrangement includes a transformer, a transformer tank and at least one tap changer that is arranged to be connected to said transformer. The transformer arrangement further includes at least one support structure which is arranged to be connected to the tap changer and to extend between the tap changer and at least two support members located between the tap changer and at least two points on an inner surface of the transformer tank. The at least one support structure is arranged to reduce pendular movement of the tap changer.

A switch unit is for a step transformer. The switch unit has: ]a controller; a motor; and an on-load tap-changer. The controller controls the motor, which actuates the on-load tap-changer. The controller draws energy, required for actuating and controlling the motor, directly from a low voltage winding of the step transformer.

A tap changing regulator with at least one regulator stage that has a set of input taps and a set of switches in a switching matrix. The have respective on-off modes to connect one or more of the taps to an output voltage to effect a number of regulation steps, where the ratio of the number of regulation steps to the number of taps is always greater than 1:1. The regulator taps are spaced between sets of windings having a progressive windings ratio of 1 to 3 to 2, or integer multiples of that ratio. Series connected additional regulator stages have an input tap with a windings ratio that is twice the sum of the first stage regulation steps, plus 1.

The regulation, power-handling capability, and reliability of a transformer is improved by a connected switching network which changes the effective numbers of turns and effective wire size of the windings synchronously during each cycle of an applied AC input voltage.

There is provided a diagnosing device for an on-load tap changing apparatus of a transformer, which can diagnose the degradation degree of insulating oil at high accuracy by a relatively simple device configuration. A diagnosing device for an on-load tap changing apparatus has an insulating oil tank in which insulating oil is sealed, a changeover switching device that is disposed within the insulating oil tank and performs the tap changing operation of a tap winding, a tap selector that selects the tap position of the tap winding, and a polarity (transposition) changer that inverts the polarity of the tap winding or a winding connected to the tap winding. The diagnosing device includes an arc discharge light detector that detects arc discharge light that is emitted at changing the tap position of the tap selector. The degradation degree of the insulating oil is diagnosed based on the arc discharge light detected by the arc discharge light detector.

Downhole electrical energy harvesting and communication in systems for well installations having metallic structure carrying electric current, for example CP current. In some instances there is a harvesting module (4) electrically connected to the metallic structure (2) at a first location and to a second location spaced from the first location, the first and second locations being chosen such that, in use, there is a potential difference therebetween due to the electric current flowing in the structure (2); and the harvesting module (4) being arranged to harvest electrical energy from the electric current. In addition or alternatively, there may be communication apparatus (4, 5, 6) for communication by modulation of the current, for example CP current, in the metallic structure (2).

A switching arrangement (1), in particular a polarity switching means, for a control transformer (10) which comprises a first winding (2) for a phase of an AC power supply system, which phase is to be controlled, comprises a first connection terminal (1.1) which can be connected to the winding (2); a second connection terminal (1.2) which can be connected to a discharge line (3); a vacuum interrupter (4); an isolator (5); a resistor (6) which is connected in series with the vacuum interrupter (4) and the isolator (5); wherein the first connection terminal (1.1) is connected to the second connection terminal (1.2) by means of the series circuit.

An example actuator assembly includes an actuator configured to move a rod. A variable differential transformer (VDT) is situated adjacent to the actuator. The VDT includes a core coupled to the rod such that movement of the rod causes a corresponding movement of the core. A plurality of windings surround the core for measuring displacement of the core. A shield surrounds the plurality of windings and shields the plurality of windings from a magnetic field of the actuator. The shield having a maximum permeability of 50,000-500,000. A LVDT configuration method is also disclosed.