scope:

This Technical Report provides guidance on how to calculate continuity of supply indices. These recommended indices are more particularly given for European benchmarking of distribution network performance. For transmission network performance, more representative indices ²⁾ may be used. It presents

- an overview of practices in Europe on long and short interruptions,

- definition of physical interruptions in a harmonized way,

- philosophy and criteria for recommending indices,

- a suggested common approach to continuity indices.

The fact that the networks in different parts of any particular country will be subject to different conditions (e.g. weather and customer density) mean that it is not viable to apply common performance standards to all networks within any one country or any group of countries without making these targets so weak that there is a good prospect of them being achieved in all areas. The present situation where national regulators set performance targets within their own countries is widely regarded as being the most effective mechanism for achieving optimal socio-economic performance. For these reasons this Technical Report does not provide common targets for the number and duration of interruptions that should not be exceeded.

This Technical Report is designed to be a first step towards benchmarking the interruption performance of European countries. Rules on the aggregation of interruptions, in particular short interruptions, have not been considered in this Technical Report, however it is recognised that it might be necessary to describe aggregation rules in a second version of the Technical Report.

²⁾ For example, "Average Interruption Time" is commonly used by TSO (AIT = T _x ENS / E_T).