Title: Types of Transformers and Their Roles (including testing)
Course: WGF 107 DEVELOPMENT > Section: Content

Sub-Title |
Content | Transformers perform voltage conversion, isolation protection, and impedance matching. In terms of voltage conversion, transformers can step up voltage and step down current from generators to high voltage transmission lines, and step down voltage/step up current to local distribution circuits or industrial customers. The step-up transformer is used to increase the secondary voltage relative to the primary voltage. The step-down transformer is used to decrease the secondary voltage relative to the primary voltage. Transformers range in size from thumbnail-sized units used in microphones to those weighing hundreds of tons interconnecting the power grid. A broad range of transformer designs are used in electronic and electric power applications, including miniature, audio, isolation, high-frequency,
Image |
Content
The operation of a transformer is based on two principles of the laws of electromagnetic induction: An electric current through a conductor, produces a magnetic field surrounding the conductor, and a changing magnetic field in the vicinity of a conductor induces a voltage across the ends of that conductor.

The magnetic field excited in the primary coil gives rise to self-induction as well as mutual induction between coils. This self-induction counters the excited field to such a degree that the resulting current through the primary winding is very small when the secondary winding is not connected to a load.

The physical principles of the inductive behavior of the transformer are most readily understood and formalized when making some assumptions to construct a simple model which is called the ideal transformer. This model differs from real transformers by assuming that the transformer is perfectly constructed and by neglecting that electrical or magnetic losses occur in the materials used to construct the device.

Transformers are used to increase voltage before transmitting electrical energy over long distances through wires. Wires have resistance which loses energy through joule heating at a rate corresponding to square of the current. By transforming power to a higher voltage transformers enable economical transmission of power and distribution. Consequently, transformers have shaped the electricity supply industry, permitting generation to be located remotely from points of demand.^[87] All but a tiny fraction of the world's electrical power has passed through a series of transformers by the time it reaches the consumer.^[38]

Transformers are also used extensively in electronic products to step-down the supply voltage to a level suitable for the low voltage circuits they contain. The transformer also electrically isolates the end user from contact with the supply voltage.

Signal and audio transformers are used to couple stages of amplifiers and to match devices such as microphones and record players to the input of amplifiers. Audio transformers allowed telephone circuits to carry on a two-way conversation over a single pair of wires. A balun transformer converts a signal that is referenced to ground to a signal that has balanced voltages to ground, such as between external cables and internal circuits.
Links/Uploads | Electrical Transformer – Wikipedia http://en.wikipedia.org/wiki/Electrical_transformer Electric Power (illustrated) – OSHA https://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/index.html Distribution System (pictorial glossary) – OSHA https://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/distribution_system.html#Transportation
Attributions | Image 1 courtesy of Wikipedia – The Free Internet Encyclopedia, and Image 2 is courtesy of OSHA – U.S. Department of Labor Content courtesy of Wikipedia – The Free Internet Encyclopedia.