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. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two 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. Large power transformers are vulnerable to insulation failure due to transient voltages with high-frequency components, such as caused in switching or by lightning. In some applications increased leakage is desired, and long magnetic paths, air gaps, or magnetic bypass shunts may deliberately be introduced in a transformer design to limit the short-circuit current it will supply. [12] Leaky transformers may be used to supply loads that exhibit negative resistance, such as electric arcs, mercury- and sodium- vapor lamps and neon signs or for safely handling loads that become periodically short-circuited such as electric arc welders. [9] :485

The EMF of a transformer at a given flux increases with frequency. [9] By operating at higher frequencies, transformers can be physically more compact because a given core is able to transfer more power without reaching saturation and fewer turns are needed to achieve the same impedance. However, properties such as core loss and conductor skin effect also increase with frequency. Aircraft and military equipment employ 400Hz power supplies which reduce core and winding weight. [17] Conversely, frequencies used for some railway electrification systems were much lower (e.g. 16.7Hz and 25Hz) than normal utility frequencies (50–60Hz) for historical reasons concerned mainly with the limitations of early electric traction motors. Consequently, the transformers used to step-down the high overhead line voltages were much larger and heavier for the same power rating than those required for the higher frequencies.The windings are wound around a core of infinitely high magnetic permeability so that all of the magnetic flux passes through both the primary and secondary windings. With a voltage source connected to the primary winding and a load connected to the secondary winding, the transformer currents flow in the indicated directions and the core magnetomotive force cancels to zero. HOW-TO GUIDES show you how to achieve a specific goal, like finetuning a pretrained model for language modeling or how to write and share a custom model. Transformers support framework interoperability between PyTorch, TensorFlow, and JAX. This provides the flexibility to use a different framework at each stage of a model’s life; train a model in three lines of code in one framework, and load it for inference in another. Models can also be exported to a format like ONNX and TorchScript for deployment in production environments.

Core losses are caused mostly by hysteresis and eddy current effects in the core and are proportional to the square of the core flux for operation at a given frequency. [9] :142–143 The finite permeability core requires a magnetizing current I M to maintain mutual flux in the core. Magnetizing current is in phase with the flux, the relationship between the two being non-linear due to saturation effects. However, all impedances of the equivalent circuit shown are by definition linear and such non-linearity effects are not typically reflected in transformer equivalent circuits. [9] :142 With sinusoidal supply, core flux lags the induced EMF by90°. With open-circuited secondary winding, magnetizing branch current I 0 equals transformer no-load current. [16] Instrument transformer, with polarity dot and X1 markings on low-voltage ("LV") side terminalThe ideal transformer model neglects many basic linear aspects of real transformers, including unavoidable losses and inefficiencies. [8] c) similar to an inductor, parasitic capacitance and self-resonance phenomenon due to the electric field distribution. Three kinds of parasitic capacitance are usually considered and the closed-loop equations are provided [10] b) Unlike the ideal model, the windings in a real transformer have non-zero resistances and inductances associated with:

This article is about the electrical device. For other uses, see Transformer (disambiguation). A basic transformer consisting of two coils of copper wire wrapped around a magnetic core Natural Language Processing: text classification, named entity recognition, question answering, language modeling, summarization, translation, multiple choice, and text generation.

Operation of a transformer at its designed voltage but at a higher frequency than intended will lead to reduced magnetizing current. At a lower frequency, the magnetizing current will increase. Operation of a large transformer at other than its design frequency may require assessment of voltages, losses, and cooling to establish if safe operation is practical. Transformers may require protective relays to protect the transformer from overvoltage at higher than rated frequency. where Z L {\displaystyle Z_{\text{L}}} is the load impedance of the secondary circuit & Z L ′ {\displaystyle Z'_{\text{L}}} is the apparent load or driving point impedance of the primary circuit, the superscript ′ {\displaystyle '} denoting referred to the primary. Winding joule losses Current flowing through a winding's conductor causes joule heating due to the resistance of the wire. As frequency increases, skin effect and proximity effect causes the winding's resistance and, hence, losses to increase. Core losses Hysteresis losses Each time the magnetic field is reversed, a small amount of energy is lost due to hysteresis within the core, caused by motion of the magnetic domains within the steel. According to Steinmetz's formula, the heat energy due to hysteresis is given by Air gaps are also used to keep a transformer from saturating, especially audio-frequency transformers in circuits that have a DC component flowing in the windings. [13] A saturable reactor exploits saturation of the core to control alternating current.

The Last Knight wasn’t exactly a massive commercial failure, but Paramount and Hasbro did lose a great deal of money on this. And thus, the Michael Bay-captained Transformers continuity was toast after 2017. While diehard fans and casual audiences would claim it was a good run, the entire thing was shut down just as the story was getting to the famous Unicron. That might explain why Paramount and Hasbro are so eager to introduce the gigantic villain as soon as possible in the new timeline. An ideal transformer is a reasonable approximation for a typical commercial transformer, with voltage ratio and winding turns ratio both being inversely proportional to the corresponding current ratio. Winding joule losses and leakage reactance are represented by the following series loop impedances of the model:One example is in traction transformers used for electric multiple unit and high-speed train service operating across regions with different electrical standards. The converter equipment and traction transformers have to accommodate different input frequencies and voltage (ranging from as high as 50Hz down to 16.7Hz and rated up to 25kV).