What does a kilowatt-hours meter measure?

The correct answer is that a kilowatt-hours meter measures the amount of power consumed over time, specifically in kilowatt-hours. This device tracks the total energy usage in a facility by quantifying how much electricity is used over a certain period, often for billing purposes by utilities.

In this context, it is important to note that while a kilowatt-hours meter can help determine the power produced or consumed by a generator, it does not measure the instantaneous power output. Instead, it accumulates the total energy used over time, thus reflecting both the power and the duration of consumption.

The other options relate to parameters that are not the primary function of a kilowatt-hours meter. The speed of the generator and the electrical current do not directly correlate with energy consumption metrics that a kilowatt-hours meter provides. Similarly, while voltage is an essential aspect of electrical systems, it is not what the kilowatt-hours meter specifically measures. This distinction is crucial for understanding how energy meters operate and their role in power engineering.