High Voltage Transformer Operation and Application

applications of high voltage transformer
High Voltage Transformer

A transformer is electrical equipment or device that converts voltage from one voltage level to another while ideally retaining input and output power the same. There are various types of transformers depending on the basis of classification. One way of classification is on the magnitude of voltage it handles, in this case, we have low voltage and high voltage types. In this article, we will discuss the high voltage transformer.

What is the high voltage transformer?

As the name suggests, this transformer has high voltage on at least one of its two sides namely primary and secondary. They are mostly of three-phase types given that they carry large power. The purpose of these transformers is quite wide as this is a broadway of classification. Suffice to say, there are modifications in design depending on the purpose as we will see hereunder.

Construction and Operation

The machine is made basically of the primary winding and secondary windings on a magnetic core. This allows magnetic induction to transfer power from the primary to the secondary side at a given frequency. The voltage transformation ratio equals the turn ratio. The key consideration in design is the insulation of the winding from parts it should not make contact. As such insulation needs make them expensive. High voltage induces high magnetic flux that causes eddy current in the core. This in turn causes heating that is cooled using pumped oil. The following factors are considered in design;

  • Voltage rating in primary and secondary.
  • Current rating in primary and secondary.
  • Power rating
  • The number of phases to be connected.

The operation is simple yet it cannot be seen for this is a static device however a live transformer produces a hamming sound, which is an undesirable outcome. Power flows from the primary coil at one voltage through magnetic linkage and the same power is induced in the secondary winding at another voltage. The fact that the two circuits are magnetically linked but electrically disconnected makes this machine offer isolation that is a desirable phenomenon. It’s worthy to note that no device is ideal and that there are transformer power losses in core heating, hamming sound, and power consumed by the oil pump for cooling. This is however negligible compared with rotary devices.

Applications Of High Voltage Transformer

As mentioned earlier there is quite a wide range of applications of high voltage transformers. Some of them are enumerated below;

  • In power transmission as power transformers- step-up voltage of generated power for transmission and step-down voltage at distribution station.
  • Isolation transformer- they offer electrical isolation of high voltage circuits and low voltage circuits. This helps to protect low voltage circuit equipment from harmful high voltage from the other circuit.
  • Control and instrumentation – potential transformer and current transformer step down high voltage to a low voltage that is measurable.
  • Step-up voltage for special equipment such as plasma generation, x-ray machine, microwave generator. It ensures the high voltage side is isolated from the primary low voltage circuit.
  • Distribution transformer – to step down the voltage for consumption by low voltage devices.


The machine is much appreciated in the power system due to its critical role. The voltage transformation capability allows engineers not to worry about the voltage rating of generators in manufacturing and installed equipment. Provided this device is available for transformation. It has allowed control, monitoring, and measurement in the instrumentation field much easily achieved. Going forward the technology is tending to small, cheaper, more efficient, and higher transformation ratio machines. As the power system grows wider and more complex, the convenience offered by this transformer will be much appreciated. For farther reading grab a book on the same information.

Read More About Transformer

Leave a Comment