What does a frequency meter measure?

A frequency meter is a device specifically designed to measure the frequency of alternating current (AC) electrical signals in hertz (Hz). It provides essential information about the number of cycles per second of the electrical waveform. In power generation, maintaining the correct frequency is crucial as it ensures that power systems operate efficiently and can synchronize with the grid.

Measuring frequency is vital for stability in power systems, especially in scenarios where multiple generators are connected. If the frequency drifts too far from the standard (typically 60 Hz in North America and 50 Hz in many other regions), it can lead to system instability or even equipment damage.

In contrast to the other choices, which pertain to different electrical parameters, the frequency meter exclusively focuses on the measurement of frequency, making option C the clear and accurate choice. Other devices are typically used for assessing voltage, current, or power factor; therefore, the other options do not align with the primary function of a frequency meter.