Toroidal Current Transformer – Why the Doughnut Shape?

Toroidal Current Transformer – Why the Doughnut Shape?

Voltage transformers come in a lot of shapes and sizes. However, many times, you see a toroidal current transformer in control circuits. CT’s are manufactured in a doughnut shape. There is a good reason for this shape, and here is more about the technology to help you understand it better.

Round is Better

By making CT’s round, a toroidal current transformer can be smaller and take up less space. This is an important consideration as CT’s may be the largest components in most control circuits these days. In a world of downsizing and miniaturizing, smaller is usually better.

The Perfect Magnetic Circuit

When you make something smaller, you may have to make some concessions. Although nothing is perfect, doughnut-shaped CTs come close. You get a smaller transformer, but you do not sacrifice performance. In fact, you can sometimes cut weight and size in half, over a standard shaped CT.


A toroidal current transformer runs cooler. The doughnut shape lends itself well to ventilation and does not store heat. A cooler running CT gives you a cooler control panel. This is very important in many industrial settings, as many companies must special use air conditioning for their control panels.


Doughnut-shaped CT’s are very efficient. In fact, there are considerably more efficient than their standard shaped counterparts. This can help to keep your control circuits running better and with fewer problems.


With a toroidal CT, you enjoy less electromagnetic interference. You might need fewer shielding applications to eliminate problems like electronic humming. Because the round shape is highly efficient, it produces less stray magnetic energy which can create problems for some equipment. Choosing the right CT can sometimes be difficult, and you should consider the many benefits of professional assistance. Your CT pros can help you choose the perfect applications.


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