Quality of supply
A high level of availability on the distribution network is a key factor in ensuring high quality of electricity supply. ElCom produces standard international measurements of the quality of supply each year to assess network availability: System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI). SAIDI quantifies the average duration of interruptions per end user, while SAIFI indicates the average frequency of interruptions per end user. Figures concerning all unscheduled interruptions lasting longer than three minutes and that occur as the result of natural phenomena, human error, operational problems or external influences are factored into the calculations for both indices.