Provided is a system for transmitting electrical energy comprising: transmitting and receiving quarter-wave resonant transformers, the quarter-wave winding of each of which is provided with contact terminals; a source of electrical energy connected to a coupling coil configured to establish a magneto-inductive link with the quarter-wave winding of the transmitting transformer with providing the possibility of exciting resonant oscillations in the quarter-wave winding of the transmitting transformer; a receiver of electrical energy connected to a coupling coil configured to establish a magneto-inductive link with the quarter-wave winding of the receiving transformer with providing the possibility of receiving electrical energy from the quarter-wave winding of the receiving transformer; an electrical energy transmission line connecting inter se the low-potential portions of the quarter-wave windings of said receiving and transmitting transformers so as to transmit electrical energy therebetween with providing the possibility of exciting resonant oscillations in the quarter-wave winding of the receiving transformer, wherein a sliding contact is connected to the high-potential terminal of each of said quarter-wave transformers, the sliding contact being configured to move along the quarter-wave winding of the quarter-wave transformer with providing the possibility of connecting to one of the contact terminals thereof.

The embodiments herein relate to a system (100) for controlling a 3-phase transformer device (101, T1, T2, T3). The system (100) comprises the 3-phase transformer device (101, T1, T2, T3) which comprises a primary side and an adjustable secondary side. The system (100) comprises at least one voltage sensor (S1, S2, S3) adapted to sense voltage at the primary side. The system (100) comprises a current sensor (S4) adapted to sense current through the adjustable secondary side, and a resistor (R1) connected in series with the current sensor (S4) at the adjustable secondary side. The system comprises a controller (103) adapted to obtain sensor data indicating the sensed voltage and the sensed current, and to control a parameter associated with the adjustable secondary side of the 3-phase transformer device (101, T1, T2, T3) based on the obtained sensor data.

An adjustable inductor, according to embodiments of the invention, includes a wire coil configured to mount on a first side of a conductive plate. The wire coil is conductive and is a plurality of windings. A core has a first portion and a second portion. The first and second portions are configured with a plurality of grooves for threading engagement with the plurality of windings of the wire coil. The threading engagement attaches the core to the plurality of windings of the wire coil, which results in varied inductance.

Embodiments of the invention disclose methods of assembling and using an adjustable inductor to vary inductance. An adjustable inductor, according to embodiments of the invention, includes a wire coil configured to mount on a first side of a conductive plate. The wire coil is conductive and is a plurality of windings. A core has a first portion and a second portion. The first and second portions are configured with a plurality of grooves for threading engagement with the plurality of windings of the wire coil. The threading engagement attaches the core to the plurality of windings of the wire coil. Rotating the core results in varied inductance.

An adjustable inductor, according to embodiments of the invention, includes a wire coil configured to mount on a first side of a conductive plate. The wire coil is conductive and is a plurality of windings. A core has a first portion and a second portion. The first and second portions are configured with a plurality of grooves for threading engagement with the plurality of windings of the wire coil. The threading engagement attaches the core to the plurality of windings of the wire coil, which results in varied inductance.