Reliability Performance

The electric power grid is essential to the economic vitality and well-being of society, making reliability of the system a social priority. It is our responsibility to operate and maintain a reliable, secure and resilient grid for all customers that meets these needs. Overall, the reliability of the power system is excellent. According to reliability metrics measured by AEP and the industry, electricity is available to our customers, on demand, more than 99 percent of the time.

However, there are times when reliability does not measure up to our customers’ expectations. Factors such as falling trees and tree limbs, severe weather and aging infrastructure do cause outages that, depending on the event, can have negative impacts on our customers. We work continually to prevent this from happening, but that is not always possible. The investments we are making in the transmission and distribution system improve reliability for customers and operating efficiency for AEP while preparing the system for new technologies of the future.

With the advent of new technologies such as energy storage, we must reconsider the antiquated view that customer connections only means the distribution service alone. A broader definition is needed to include other technologies that enhance customer reliability even if a distribution outage occurs.

Reliability Metrics

There are three key metrics by which we measure the reliability of our system.

  • The System Average Interruption Duration Index (SAIDI) measures the minutes of an outage that an average customer experiences in a given year. Our performance in 2017 improved by 10.6 percent compared with 2016 (excluding major events). Vegetation growing or falling into power lines accounted for 33 percent of SAIDI results, while 19 percent was related to distribution line equipment issues.
  • The System Average Interruption Frequency Index (SAIFI) measures the number of power interruptions per year experienced by customers. During 2017, SAIFI improved 2.7 percent compared with 2016. Again, vegetation and equipment failures were major contributors to performance.
  • The Customer Average Interruption Duration Index (CAIDI) reflects the time it takes to restore power. In 2017, CAIDI deteriorated by 2.2 percent compared with 2016. The severity of damage to our equipment most often dictates the length it takes to restore service.

The first thing a customer wants to know when the lights go out is when they will be on again. Being able to provide customers with a global estimated time of restoration (ETR) is essential to customer satisfaction. According to the J.D. Power Residential Electric Survey, customer satisfaction increases if power is restored before the ETR. Similarly, it decreases if power is not restored by our estimate.

During the past two years we have developed new tools to make it easier for our customers to report an outage when it occurs and to track estimated times for service restoration. For example, customers can get information about their ETR by text message or email if they sign up for their utility company’s alerts. The ETR alert system is giving customers better information about service restoration timing. Because it is so important to our customers, we are constantly seeking ways to keep customers apprised about outages and to improve the ETR.

In December 2017, AEP debuted a new mobile app. By downloading it onto their smart phones, customers can pay their bill and report and monitor power outages. The app is one example of how AEP is working to make it easier for customers to interact with us. It also provides an important channel for reporting and sharing information during outage events.

In addition to the app, customers can access an online interactive map that makes it easier to get detailed information about power outages. The outage map features:

  • Greater transparency about restoration progress for customers, media and community leaders who need this information.
  • Easily accessible and more detailed information, such as unplanned power outages, always available, without the need to log into a customer account.
  • Interactive maps that are mobile-friendly and allow users to zoom in to see power outages by street or neighborhood. Outages are displayed as color-coded icons and area polygons. Users can search for details by street, city, zip code or county, without logging in.