Different Types Of Power Transformers And Their Uses

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A power transformer is a static machine used for transforming power from one circuit to another without changing the frequency. Power transformers are used between the generator and distribution circuits, where there is a transition between voltage levels. The entire power system consists of large number of generation locations, distribution points and interconnections within the system or neighbouring systems. A transformer helps in minimizing the loss of power even at very high voltages because of its resistance. It carries the received power to an exact range to ensure that the power is utilized according to the requirement only. There are many different types of transformers and each type is used for a different purpose. Here is a list of some of the most widely used transformers and how they are beneficial.


Smaller, lighter and cheaper than standard dual-winding transformers, autotransformers do not provide electrical isolation. These transformers have a part of their winding included in both input and output circuits – voltage is applied across a portion of the winding, and a higher or lower voltage is produced across another portion of the same winding. Thus, these transformers can step up or down between voltages in the 110-117-120 and 220-230-240 volt ranges. The equivalent power rating of an autotransformer is lower than the actual load. Large three-phase autotransformers are used in electric power distribution systems.

Polyphase transformers

Power distribution systems require three-phase transformers to be able to step up or down voltages. However, single-phase transformers can be joined together to transform power between two three-phase systems too. However, there are special three-phase transformers manufactured for such tasks which require lesser material, and are smaller in size and weight than their modular counterparts. These transformers are made of three sets of primary and secondary windings, where the three primary windings are connected together, and the three secondary windings are connected together. The main purpose of a polyphase transformer is for grounding and suppression of harmonic currents.

Leakage transformers

Also known as stray-field transformers, leakage transformers have a significantly higher leakage inductance than other transformers, which can be increased by a magnetic bypass or shunt in the core between primary and secondary windings. It can also be adjusted with a set screw. Due to the loose coupling between the windings, these transformers have a current limitation. The input and output currents of these transformers are low enough to prevent thermal overload in any situation. Leakage transformers can act as both voltage transformers and magnetic ballast, and are used for arc welding, high voltage discharge lamps, doorbells and short-circuit-proof extra-low voltage transformers for toys.

Resonant transformers

A resonant transformer is one that has one winding with a capacitor, which acts as a tank/tuned circuit. They are driven by pulse or square wave and can function as high Q-factor bandpass filters. These transformers utilize the leakage inductance of the secondary winding combined with external capacitors to form one or more resonant circuits. They are widely used in radio circuits and switching power supplies. The Tesla coil is one such example that is used to generate very high voltages, and is able to provide much higher current as compared to high voltage electrostatic machines.

Miracle Electronics manufactures high quality power transformers in India that provide the highest level of safety to the operator by regulating and stepping down voltages, and allowing flawless use of grounded and ungrounded circuits. Miracle Electronics’ power transformers are RoHS compliant and reach compliant, and are also available with CE and UL marks with request. They also manufacture other types of transformers including toroidal, medical isolation, audio output, E&I, UI and more.

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