Power:Transformer Load Tap Changers

Transformer Load Tap Changers

A tap changer is a mechanism in transformers which allows for variable turn ratios to be selected in distinct steps. This is done by connecting to a number of access points known as taps along either the primary or secondary winding.

Figure 1 - Load Tap Changer

I. Introduction

The flicker of the house lights in the evening when most people are at home and started using electricity for household chores is a sign of a load tap changer (LTC) tap change. The increase in electrical load on the distribution network causes the voltage to sag below its nominal value. This voltage sage triggers a signal to the LTC to change taps to adjust the voltage back to its nominal value with some tolerance.

There are many applications of transformers in modern electric power systems. The role of a transformer is to convert the electrical energy from one voltage level to another. As power systems become larger and more complex, power transformers play a major role in the efficiency and stability of the power the system. Each transformer installed in a network, there is an optimal voltage ratio for an optimal operation of the system. Unfortunately, this optimal voltage ratio varies depending on the operating conditions of the total network. Early electric power systems, it was evident that for the power systems to operate efficiently, transformer voltage ratios needed to be adjustable without interrupting the flow of energy. This is the role of an LTC.