What kind of transformers are used to measure power line voltages?

The correct answer refers to potential transformers, which are specifically designed to measure high voltages in power lines accurately. These transformers step down high voltage levels to a lower, safer level that can be easily measured and utilized by standard measuring instruments.

Potential transformers are utilized in electrical systems for voltage measurement purposes due to their ability to provide a scaled-down replica of the actual voltage, while maintaining the same phase relationship. This transformation is essential for protective and metering purposes, allowing operators to monitor and control the electrical grid without directly exposing measuring equipment to high voltages, thus ensuring safety and accuracy in readings.

In contrast, current transformers are used to measure current, not voltage, by stepping down current levels. Step-up transformers increase voltage levels, while isolation transformers provide isolation between circuits without necessarily measuring voltage. Understanding the purpose and application of each type of transformer clarifies why potential transformers are the correct choice for measuring power line voltages.