Toroidal Transformers

Custom Toroidal Transformers

Toroidal transformers are known to maximize power and minimize size and weight, thanks to their unique configuration.
Toroidal design is also ideal for reducing electromagnetic interference, leakage inductance, and audible noise.

We welcome the opportunity to work with you on your toroidal transformer requirements, whatever your application or market. Weighing the advantages and trade-offs, we will happily help you determine which type of transformer best meets your needs—electrical, mechanical, and budgetary alike. Whether an isolation transformer, autotransformer, or inductor, standard EI, pieced lamination, or toroidal construction, low voltage, high voltage, high frequency, whatever your ideas or needs, you can count on Johnson Electric Coil Company to provide a solution that works for you.

For further information on our toroidal transformers or any of our products and services, give us a call today!

Toroidal transformers are donut shaped, exceptionally efficient, quiet operating, and low heat generating transformers. They have primary and secondary windings around the donut shape core that are separated by insulation to minimize magnetic flux leakage. Toroidal transformers step power up or down in accordance with the magnetic field that passes through the secondary coil.

The design and compactness of toroidal transformers provides flexibility compared to other types of transformers. They are used with low kilo volt ampere (kVA) rated devices and medical, industrial, and renewable energy equipment as well as for audio applications.

How a Toroidal Transformer Works

The purpose of any transformer is to transfer electrical energy from one circuit to another using a magnetic field to change the electromotive force. During the transfer process, the electrical circuits are isolated from each other. The key factor for a transformer is maintaining the electric current frequency during step up or step down.

The core of a transformer can have the solenoid shape of a square or rectangle or a toroid round or donut shape. The benefit of the circular toroid shape of a toroidal transformer is that the magnetic flux easily forms a loop without the need of a return path. This design makes toroidal transformers more efficient than the solenoid design. Their distinct shape allows for shorter windings, a reduction in stray losses, and improved efficiency.

The basic problem with ordinary transformers is the air gap in the core, which does not magnetically saturate and causes magnetic flux leakage. The special construction of toroidal transformers eliminates air gaps and magnetic flux leakage. Coils are wound uniformly over the donut shaped core allowing machines to operate at higher flux density.

Benefits of Toroidal Transformers

The wide use of toroidal transformers is due to their light weight and smaller size, which allows them to be adapted to a wide range of applications. Aside from these physical benefits, there are several other positive aspects related to the use of toroidal transformers.

• Volume – The higher flux density of a toroidal transformer is possible due to the magnetic flux being in the same direction as the rolling direction of the grain of the core, which saves on volume and weight. Higher current density can flow through the surface of the core allowing for efficient cooling.

• Efficiency – The magnetic circuit of a toroidal transformer, with its ability to run at a higher flux density, reduces the number of turns of wire for the transformer as well as its cross sectional area. These factors make it possible for a toroidal transformer to work at 90 to 95 percent efficiency, which meets legislated efficiency standards.

• Noise – A hum is created in most transformers when the windings and core layers vibrate because of the forces between the coil turns and core lamination. As the laminations loosens, the noise of the hum gradually increases. Toroidal transformer cores are tightly wound, spot welded, annealed, and coated without any air gaps eliminating loose sheets or windings from vibrating.

• Dimensions – Toroidal transformers can be produced in any diameter and height to meet the needs of any application. They are found in sound systems, medical equipment, and industrial applications in designs that can fit in the palm of the hand.

• Stray Fields – Stray fields are far lower with toroidal transformers, which is an important consideration for design engineers since stray fields can produce unwanted and unnecessary noise and interfere with sensitive electronics.

• Temperature – Toroidal transformers have very low iron loss that result in small magnetizing currents and excellent temperature ratings. The benefit of low iron loss is reduction of load power loss, which enhances a toroidal transformer’s efficiency.

Electrical energy losses are converted into vibrations and heat that generates eddy currents, hysteresis, and copper resistance. The high efficiency of toroidal transformers causes them to generate less heat and eliminates the need for a cooling system.

Uses for Toroidal Transformers

Toroidal transformers are used in a wide range of applications due to their flexibility and compact size. They have an endless number of uses and are especially useful to highly technical equipment and conditions where vibrations and noise can diminish performance.

• Audio Equipment – Distortion in the performance of audio equipment can negatively affect a live performance, consumer products, and the production of recordings. Noise, vibrations, and different sounds can damage an amplifier or other audio devices. The use of toroidal transformers eliminates unnecessary vibrations and hums to produce superior sound quality. They have less audible hum because they have a lower flux density.

• Renewable Energy – The shape of toroidal transformers is ideal for use in the renewable energy industry. Their efficiency, compact shape, and flexibility make it possible for toroidal transformers to deliver the performance required. With solar energy, high efficiency inverters need to have DC electricity from the solar panels converted to AC power. Toroidal transformers are used as inverters for low loss power output.

• Medical Equipment – Toroidal transformers are used for medical equipment because they are able to meet the very strict safety, performance, and reliability standards set for medical equipment. A key factor for medical equipment is a long useful life, which toroidal transformers are more than capable of meeting.

Medical toroidal transformers have a flux band that provides an additional layer of protection against stray fields between the primary and secondary coils. The flux bands reduce current leakage and interference from mode signals.

• Industrial Applications – The exceptional durability of toroidal transformers make them the first choice for use with industrial equipment. An essential part of industrial operations is reliability in order to avoid production shutdowns and delays. The efficiency and strength of toroidal transformers make them the perfect choice for any process, equipment, or application.

Types of Toroidal Transformers

The function of all toroidal transformers is basically the same. The variations between the different versions is how their basic designs are configured and combined.

• Three Phase Toroidal Transformer – The three phase version of toroidal transformers is made up of three single phase toroidal transformers. This design makes it possible to assemble and configure the individual single phase transformers in multiple ways. They are a cost effective solution for higher kVA rated applications.

• Miniature Toroidal Transformers – These small sized toroidal transformers have lower core loss, operate at higher flux density, and can be easily mounted using a bolt through the center hole of the transformer. They have the qualities of larger toroidal transformers in a smaller size.

• Encapsulated Toroidal Transformers – This form of toroidal transformer is encapsulated in a plastic case and is designed for through hole mounting like miniature toroidal transformers. They have a low profile, low magnetic field radiation, and kV isolation between the primary and secondary windings.