Service Quality

Service quality in 2010 recorded decidedly positive figures for Regulated Energy Not Supplied (RENS) and the Number of Supply Failures per User (NSFU), falling below the averages seen in recent years: RENS of 1005 MWh vs. quality target of 1241 MWh and NSFU of 0.179 vs. quality target of 0.214.
In 2010, a major incident was recorded in the 150 kV grid in the area of Naples. The forest fires had a limited effect on the availability of the transmission system. This situation meant that low values of energy were not served, albeit slightly above the predefined target.

Critical issues generated by causes not attributable to Terna included storms, strong wind and, in some cases, significant snowfall in the areas of Turin, Naples and Palermo, which led to an increase in the number of supply failures per user, although performance on a national level was above the predefined target. No gas and water availability-related critical issues were recorded.

Although in line with the positive service quality generally, the larger islands continued to face their particular challenges connected with the structure of the transmission system. In conclusion, the following are the four key indices of service quality and performance for Terna’s NTG systems, which are calculated in accordance with Resolution no. 250/04 of the Authority for Electricity and Gas and Terna’s Grid Code and which all show positive results:

  • AIT (Average Interrupt Time attributable to Terna) = 0.99 min/period; Annual national target = 1.00 min/year;
  • SAIFI + MAIFI (System and Momentary Average Interruption Frequency indexes per user directly connected to the Terna NTG, attributable to Terna) = 0.15; Annual national target = 0.22;
  • ENS (Energy Not Supplied attributable to Terna) = 613 MWh; Annual national target = 550 MWh;
  • ASA (Average System Availability of Terna network elements) = 99.225%; Annual national target = 99.05%.