In alternate current lighting the induction coil by which the primary current with high initial electro-motive force is caused to produce a secondary current with low initial electromotive force. A typical transformer consists of a core of thin iron sheets. The primary is of comparatively thin wire and often of ten or more times as many turns as the secondary. The latter is of thicker wire. Where the ratio of 10 to 1 as regards number of turns in the primary and secondary obtains, the initial E. M. F. of the secondary is one-tenth that of the primary circuit. The cores are laminated, as described, to avoid the formation of Foucault currents. The counter-electro-motive force of the transformer when the secondary circuit is open, prevents any but the slightest current from passing through the primary. In proportion as the secondary is closed and its resistance diminished, as by lighting more lamps in parallel, the counter-electro-motive force of the transformer falls and more current passes through the primary. Fig. 339. FERRANTI'S TRANSFORMER. The economy of the apparatus is in the fact that counter-electromotive force reduces current through a conductor without absorbing any energy. A resistance coil cuts down a current, but absorbs energy equal to the current multiplied by the potential difference between the terminals of the coil. This electric energy is converted into heat energy and is wasted. But the counter-electromotive force of a transformer is exerted to reduce current without production of heat and with little waste of energy. This is one of the advantages of the alternating current system of distribution of electric energy. The object of a transformer being to secure safety to the person or to life by the separation of the high potential primary or street circuit, and the low potential house circuit, any contact of the two circuits in the converter is a source of danger. Special care should be taken to ensure absence of leakage, as it is termed. Mica or other insulation is sometimes employed to prevent the wires from coming in contact by piercing or sparking with the core and with each other.

(transformers)

A transformer is a deep learning model that adopts the mechanism of self-attention, differentially weighting the significance of each part of the input data. It is used primarily in the fields of natural language processing (NLP) and computer vision (CV).

A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force (EMF) across any other coils wound around the same core.

A balun (from "balanced to unbalanced", originally, but now dated from "balancing unit")"balun", Oxford English Dictionary online, retrieved 28 July 2021 . is an electrical device that allows balanced and unbalanced lines to be interfaced without disturbing the impedance arrangement of either line.

<electronics> A transformer connected between a balanced source or load and an unbalanced source or load. A balanced line has two conductors, with equal currents in opposite directions. The unbalanced line has just one conductor; the current in it returns via a common ground or earth path. (1996-10-17)

BALanced-UNbalanced [Additional explanations: adapter] (Reference: cable), "Style: Balun"