Ignazio Mastandrea*, Riccardo Chiumeo*, Francesco Tarsia*, Oscar Ornago*, Guido Carpinelli**, Pierluigi Caramia***, Pietro Varilone***, Paola Verde*** EPQU 2007 – 9th International Conference Electrical Power quality and utilization, Barcellona, Spagna 9-11 Ottobre 2007 * CESI RICERCA **Università di Napoli Federico II *** Università di Cassino The presence of the new liberalized markets has increased interest in power quality disturbances due to their economic value. Customers have more choices; then disturbances are becoming bigger issues and suppliers and customers should regulate them in the frame of power quality contracts. A single global power quality index can be very useful for characterizing the overall level of the voltage waveform quality; in particular, this index can provide global indications regarding different aspects of voltage quality and allows a strong reduction of the measurement data needed to cover all power quality disturbances. in this paper, a global power quality index (GPQI) for discrete disturbances is proposed, based on the discrete severity indicators (DSI). We present the results of a GPQI evaluation of an Italian distribution system on voltage dips, whose measured data are available on the website of the project QuEEN led by CESI Ricerca.