ДЄ varying current in the transformer's primary winding attempts to create a varying magnetic flux in the transformer core, which is also encircled by the secondary winding. Perfect coupling implies infinitely high core magnetic permeability and winding inductance and zero net magnetomotive force (i.e. V P = в€’ N P d О¦ d t denoting referred to the primary.ДЄn ideal transformer is a theoretical linear transformer that is lossless and perfectly coupled. Transformers range in size from RF transformers less than a cubic centimeter in volume, to units weighing hundreds of tons used to interconnect the power grid. A wide range of transformer designs is encountered in electronic and electric power applications. Since the invention of the first constant-potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electric power. Transformers can also be used for isolation, where the voltage in equals the voltage out, with separate coils not electrically bonded to one another. Transformers are most commonly used for increasing low AC voltages at high current (a step-up transformer) or decreasing high AC voltages at low current (a step-down transformer) in electric power applications, and for coupling the stages of signal-processing circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. A varying current in any one coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force across any other coils wound around the same core. ДЄ transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. Pole-mounted distribution transformer with center-tapped secondary winding used to provide ' split-phase' power for residential and light commercial service, which in North America is typically rated 120/240В V.

Se transformer en en anglais