What Is a Voltage Transformer?

A voltage transformer is an electrical component that can step up, step down, or transfer a current of electricity between circuits. Designed to control the voltage of a current, especially in high-voltage scenarios, voltage transformers tend to provide a specific level of power. Though most often used for devices needing 500 volts or more, a voltage transformer also can be found in many low-voltage electronic devices.

Regardless of size, a voltage transformer relies on the properties of mutual induction. A current at any voltage is passed through a primary set of transformer coils. The motion of this current past a transformer core creates a variable electromotive force in a secondary set of transformer coils. The amount of turns in the two coils controls whether the current gets stronger, weaker or stays the same. This process is perhaps most useful in high-voltage and long-range circuits.

High-voltage transformers are often used within large electrical grids. The varying levels of voltage needed throughout a grid means that, at various points, the amount of voltage might need to be reduced or increased so equipment can function properly. Substations and power plants often contain significant arrays that include voltage transformers, and civic applications often rely on a high-voltage transformer at some point.

In these large-scale electrical grids, maintenance and metering is often required. High-voltage transformers are often used to reduce power from a grid to the level that metering equipment will be expecting. Stepping down the voltage can reduce the load on such equipment without interrupting the grid's current overall. The same basic concept is often applied to low-voltage equipment.

Many electronics contain power transformers that turn household voltage into an acceptable level for a particular device. These voltage transformers can be external, such as common AC adapters, or internal, such as components inside a computer power supply. Commercial opportunities stem from the range of devices and electrical currents used across the globe.

A low-voltage transformer, for instance, might be helpful when traveling to a country that uses a different voltage for in-home power. Commercial voltage transformers are often designed to convert wall power into a voltage that electronic devices can use. Like high-voltage transformers, low-voltage transformers can be used to step the voltage up or down using transformer coils. Many of the same rules and concepts used in large scale electrical grids apply to consumer electronics.