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.

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. We will never let you walk out the door with a substandard product. If high quality is demanded, that is what we will offer. Let us help you today! Give us a call or visit us online to learn more.

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Johnson Electric Coil Company $$$

Stockton, CA  |  800-628-1123

West Coast Magnetics is a leading supplier of standard and custom transformers and magnetics to OEM manufacturers of electrical and electronic equipment. Standard options include current transformers, power inductors, base drive transformers and more. Additionally, our engineering department has extensive experience in the design and build of custom power transformers suited to your application.

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West Coast Magnetics $$$

Pelham, NY  |  800-431-1064

At Pico Electronics, we are a big name in small components. Our excellent customer service and support is a wonderful accompaniment to our quality electric transformers. We also have capabilities to provide custom transformers, power transformers, current transformers, isolation transformers, toroidal transformers and high voltage transformers. For more information, contact us today and tell us how we can fulfill your requirements.

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Pico Electronics, Inc. $$$

Trenton, NJ  |  800-747-0845

Established in 1968, Power Magnetics engineers and manufactures electric transformers, low and high voltage transformers, current transformers and distribution transformers. We also can produce custom transformers to meet your needs.

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Power Magnetics, Inc. $$$

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. When you do business with Lenco, you can do it with confidence that your product was designed and engineered by professionals. Your special application is our specialty, so call Lenco today!

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Lenco Electronics, Inc. $$$
placeholder image Johnson Electric Coil Company West Coast Magnetics Pico Electronics, Inc. Power Magnetics, Inc. Lenco Electronics, Inc.

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