Comparison of transformers on a toroidal and inlaid core

   In this article, we will review only two parameters - the impact on the environment. environment and dimensions. We have reviewed other parameters earlier. See on our website.

 There are several factors that favorably distinguish a toroidal transformer from a type-setting - when it is required to take into account the impact on the environment:

A toroidal transformer weighs about half the weight of a conventional transformer with the same power and operating temperature. The main materials used in the manufacture of transformers are copper and steel, and their volume is reduced by the manufacture of toroidal transformers. 
There is no need for impregnation in the production of torus, in contrast to the production of inlaid cores, when it is necessary to reduce the "hum of the transformer". Impregnation is a potential hazard for the environment, not only in the production process, but also in the process of using the transformer.
The toroidal transformer fits in a smaller volume, which reduces the size of the chassis and enclosures in which it is used, as well as the convenience of mounting and positioning in the device. The toroid allows both horizontal and vertical mounting. You can also attach directly to the PCB by pouring and threading the compound into the middle of the torus, not even requiring metal mounting plates. In the case of a type-setting transformer, the plates and the construct are necessary for tightening the laminated core.

There is also a difference in the cooling of an operating toroidal transformer compared to a multilayer transformer. The design of the torus is such that free cooling is often sufficient because most of the winding is evenly in contact with air



The lighter weight of the transformers indirectly reduces the cost and environmental impact of transporting raw materials and transformers from manufacturer to customer.

Why is a toroidal transformer about half the size of a classic transformer?

There are 2 factors that contribute:

In the multilayer core of the stacked transformer, individual E- and I-shaped plates are stamped from grained steel. The magnetic flux travels easily along the grain, but worse travels through the grain as part of the path around the winding coil.

In a toroidal transformer, the core is wound like a roll of grained steel tape. The magnetic flux will go along the grain throughout the whole frame.

As a consequence, a multilayer transformer core with flux densities of 10,000 to 12,000 Gauss (1.0-1.2 Tesla) can be used. The core of a toroidal transformer is typically sized with flux densities between 15,000 and 16,000 Gauss (1.5-1.6 Tesla), resulting in a weight reduction of approximately (1.2 / 1.5 x 100 =) 20%.

On the toroidal core of the transformer, copper wires are wound around the entire circumference, which allows many turns to be made before a new layer of winding has to begin.

With a multilayer transformer, the coil is used to wind the primary and secondary windings. The bobbin width is limited because it must fit into the core window. As a result, many layers of windings need to be wound, and the length of the wire will increase with each layer, and the average turn length will increase as more layers are needed. The weight of one turn of copper increases with the length of that turn, so the total copper weight for the entire winding will be higher than for winding on a toroidal core, where the (virtual) bobbin is much wider and fewer layers are required, with a lower average weight per stroke as a result.

Автотрансформатор маломощный


A secondary, less important effect also comes into play. With a longer average turn length in a multilayer transformer, the resistance in the winding increases, so a heavier wire or more turns must be used to compensate for the voltage drop in the winding.

The actual weight savings for a toroidal winding versus a multilayer winding of a transformer depends on the actual design of the particular transformer, but our many years of experience show that a toroidal transformer is about 50% of the weight of a classic transformer.

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