A potential transformer (PT), also known as a voltage transformer (VT), is a type of instrument transformer used in electrical power systems. Its main purpose is to step down high voltage levels to a lower, measurable voltage suitable for use in meters, relays, protective devices, and other control and monitoring equipment.
The primary function of a potential transformer is to provide an accurate and scaled-down voltage proportional to the voltage on the power system it is connected to. This allows electrical instruments and devices to operate safely and accurately with reduced voltage levels, as the direct measurement of high voltages would be impractical and dangerous.
The construction of a potential transformer typically involves a primary winding connected in parallel with the power line whose voltage needs to be measured and a secondary winding connected to the measuring equipment. The secondary winding has a large number of turns compared to the primary winding, resulting in a reduced output voltage. The turns ratio between the primary and secondary windings determines the voltage transformation ratio of the PT.
Potential transformers are commonly used in electrical substations and power transmission systems, where they enable accurate measurements and provide reference voltages for protective relays and control devices. They play a crucial role in ensuring the safety and efficiency of the power grid by providing reliable voltage measurements for various operational and protective purposes.