Can You Use DC on a Current Transformer?

Current transformers are a staple tool in any industry that uses electricity. Basically, a current transformer takes in a current that is too powerful and reduces it (“step down”) to a more manageable quantity. It does this by using coils or windings, with the primary one accepting the input current and the secondary winding producing the output current. Since the output current is proportional to the input one, you can easily measure the former by noting the number of coils the secondary winding has.

Of course, the type of current you introduce into the transformer plays a vital role, too. As it happens, many people wonder why you can’t use a direct current (DC) power system with transformers for power distribution.

The answer is simple: electromagnetic induction. A direct current is unidirectional, so the magnetic field it creates in the primary and secondary coils are unchanging. Unfortunately, without a changing magnetic field, electrons will not travel from one coil to the other, and thus the current cannot be “stepped down.”

What can you do to measure and reduce a direct current? One way to do this is to pulse the DC voltage supplied to the transformer. Another method is to transform the DC to an alternating current or AC. As the name suggests, an AC naturally creates a changing magnetic field, making it ideal for use with transformers.