what is a potential transformer?

A potential transformer (PT) is a type of instrument transformer that is used to measure voltage in an electrical power system. It is designed to provide a voltage in its secondary winding that is proportional to the voltage in its primary winding, while isolating the measuring instrument from the high voltage of the primary circuit. This allows for the use of low-cost, low-power instruments for measuring the high voltages in power transmission and distribution systems.

Potential transformers provide a safe and accurate method of measuring high voltages, the ability to isolate the measuring instrument from the high voltage of the primary circuit, and the ability to be used with a wide range of instruments and equipment. They are also relatively inexpensive, easy to install and maintain.

They have a limited measurement range with accuracy and can become saturated if the primary voltage exceeds their rated capacity. Additionally, potential transformers can be affected by external magnetic fields, which can cause errors in measurement.

Potential transformers are used in a wide range of applications, including power transmission and distribution systems, industrial and commercial power systems, and residential electrical systems. They are typically used in conjunction with current transformers for wattmeters, and other types of measuring instruments to provide accurate and reliable measurements of voltage in electrical power systems.

In power transmission and distribution systems, potential transformers are used to measure the voltage on the high voltage transmission lines and distribution feeders. They are also used in substations and switchyards to monitor the voltage in the primary and secondary circuits. In industrial and commercial power systems, potential transformers are used to measure the voltage in the feeders and branch circuits of the power distribution system. They are also used to measure the voltage in the motor circuits and other equipment.

In residential electrical systems, potential transformers are used to measure the voltage in the main service panel and in the individual branch circuits. They are also used to measure the voltage in the subpanels and other equipment.

In power electronics, potential transformers are used to measure the voltage in the primary and secondary circuits of inverters, motor drives, and renewable energy systems. They are also used in protection and control systems to detect faults in the electrical power system and to trip the breaker in the event of a fault.

Overall, potential transformers are a crucial component in electrical power systems and play a vital role in measuring the voltage in the high voltage transmission and distribution systems, industrial and commercial power systems, and residential electrical systems.