For what percent of the year should BA's frequency and ACE metering equipment maintain a minimum accuracy of 0.001Hz?

The requirement for balance authority (BA) frequency and Area Control Error (ACE) metering equipment to maintain a minimum accuracy of 0.001Hz is set to ensure precise monitoring and control of system frequency, which is critical for maintaining reliability in the electric grid. The standard percentage is defined as 99.5% of the time over the year.

This high level of accuracy is important because the frequency of the electric grid can fluctuate due to variations in load and generation. Maintaining an accuracy threshold of 0.001Hz helps to ensure that these fluctuations are detected accurately, allowing for prompt responses to any deviations that could threaten system stability. Achieving this standard 99.5% of the year means that not only is the equipment expected to perform accurately most of the time, but it also allows for a small margin for maintenance or other issues that could affect measurement accuracy.

Therefore, the chosen answer reflects a critical balance between reliability and operational practicality in the context of electric grid management.