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Auto Transformers

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Some typical applications of auto transformers include use as voltage regulators and speaker adapters as well as to simulate low line conditions for testing, interconnect systems and for impedance matching. Read More…

Auto Transformers An auto transformer, also referred to as an autoformer, is a general term for an electrical transformer with one winding, as compared to more traditional two-winding transformers. Transformer windings are coils wrapped around a magnetic core. Since auto transformers have fewer windings and a smaller core, they are often used as alternatives to two-winding transformers such as isolation transformers, because they are often more efficient as well as being less-expensive and physically smaller.
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Leading Manufacturers

Antigo, WI  |  800-826-9741

We believe in offering the very best to all customers. We offer a full range of transformers, including electric transformers, current, and toroidal transformers.

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Johnson Electric Coil Company $$$

Perris, CA  |  951-277-0757

With more than 500 current transformer manufacturers in the world, Triad Magnetics realizes you have a choice. Why choose Triad? Having served the needs of many industries for more than half a century, Triad believes its experience makes the difference. And if there is one point experience has taught it, it is that it must remain flexible and adaptable to the changing needs of the market.

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Triad Magnetics $$$

Gaobu Town, OVR  |  818-863-9000

22 years in the transformer industry since DELTA Electronics, PROWELL is an EMS provider as well as a leading manufacturer specializing in producing Magnetic LED lighting drivers, power adapters, electric transformers, linear power transformers, toroidal transformers ring core inductors, Experienced in precise die casting mold, plastic injection molding parts and metal sheet stamping in South China , we can cooperate with clients’ engineer to turn design ideas into perfect products. our major marketing is in USA, CANADA and UK.

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Dongguan Winshine Electric Co., Ltd. $$$

McHenry, IL  |  815-344-2900

Lenco Electronics, Inc. specializes in a wide variety of custom electric transformers. Lenco’s success has not come about by accident, but by providing its customers with high-quality products.

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Lenco Electronics, Inc. $$$

Mount Holly, NJ  |  800-856-7699

With over 40 years of experience, we’ve designed and manufactured a wide array of mid- to high-frequency electronic transformers in numerous sizes and shapes. We specialize in toroidal, pot core, e core and bobbin-based transformers, as well as baluns, chokes, bar chokes and more. Plus, our winding specialists can manufacture components that fit into even the smallest spaces.

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Mech-Tronics $$$
placeholder image Johnson Electric Coil Company Triad Magnetics Dongguan Winshine Electric Co., Ltd. Lenco Electronics, Inc. Mech-Tronics

While auto transformers have many advantages over two-winding transformers, 3 phase transformers are used in applications in which auto transformers are not appropriate.Such applications include controlling harmonic currents and providing a source of ground fault currents. Used in equipment such as motor starters, boosters and static balancers, auto transformers are often used in the automotive, commercial, power transmission, electronics, telecommunications and marine industries.

115/277V Autotransformer Auto Transformers - MCI Transformer Corporation

Auto transformers consist of a single winding and an input and output circuit. Common to both circuits, the winding has at minimum three electrical connection points that are referred to as taps. The voltage source and the load are both connected to two of the taps. One tap at the end of the winding serves as a common connection to the source and the load circuits.

The lack of insulation between the input and output circuits is a disadvantage of auto transformers, because a failure of the winding could result in the full input voltage being applied to the output. There are many different types of auto transformers: zig zag transformers, step-up transformers, step-down transformers and variable auto transformers.

Zig zag transformers are special-purpose transformers that are intended for use in providing earthing for ungrounded electrical systems. Step-down transformers convert higher voltages to lower voltages by having fewer secondary coil windings, while step-up transformers' higher number of secondary coil windings allow them to convert lower voltages to higher voltages. Variable auto transformers are only applicable for low voltage designs and are often referred to as variable AC transformers.

Auto Transformer Informational Video