Which index represents the total number of momentary customer power interruptions within a period?

The Average Interruption Frequency Index (MAIFI) is the correct choice, as it specifically measures the frequency of momentary interruptions experienced by customers over a defined period. This index counts how many times power outages occur, regardless of their duration, effectively capturing the total number of momentary interruptions.

Understanding the context of the other indices highlights the uniqueness of MAIFI. The System Average Interruption Duration Index (SAIDI) focuses on the total duration of outages, measuring how long customers are without power on average. The Customer Average Interruption Duration Index (CAIDI) looks at the average duration of interruptions that customers experience, derived from the total outage duration over the number of sustained interruptions. The System Average Frequency Index (SAFI) primarily assesses the average frequency of all types of interruptions, but it does not specifically highlight momentary interruptions like MAIFI does.

Thus, MAIFI is tailored to reflect the count of brief interruptions, making it the appropriate index for the question at hand regarding momentary power interruptions.