Cerca nel sito per parola chiave

pubblicazioni - Memoria

Live line work on HV lines equipped with composite insulators: state of the art

pubblicazioni - Memoria

Live line work on HV lines equipped with composite insulators: state of the art

La memoria in oggetto si pone lo scopo di realizzare uno stato dell’arte dell’impiego degli isolatori compositi sulle line elettriche aeree di alta tensione nel mondo. In particolare vengono illustrate le moderne tecniche diagnostiche di ispezione (con una approfondita analisi delle potenzialità e degli ambiti di impiego) utilizzate per la valutazione dello stato dei componenti in esercizio e lo stato della normativa per i lavori sotto tensione (IEC 61472), che ancora non copre i componenti in esame. A questo riguardo viene illustrata la proposta per una sua revisione avanzata dal Comitato Nazionale Italiano e vengono forniti contributi all’attività sulla base di una approfondita analisi dei risultati dell’estesa campagna sperimentale realizzata negli ultimi anni da RSE.

At present, non-ceramic insulators (NCI) also called composite insulators are widely used on overhead lines (OHL) all over the world with many advantages, e.g. in terms of weight and performance under polluted conditions. An essential issue that limits an even wider application of NCIs is the difficulty to assess their condition in service before the application of live line working (LLW) techniques for the replacement or repair of the insulators or related hardware. Some utilities already have good experience in inspecting the conditions of NCIs and in working on these components using LLW techniques while others need support in developing of such techniques. Minimal required conditions for LLW are given in [1] [2]. IEC Standard 61472 [2] describes the method for the calculation of working distances in case of porcelain or glass cap-and-pin insulators, and defines the criteria to assess the maximum allowable number of damaged units depending on the voltage class and the overvoltage level considered. Minimum requirements for composite insulators are not covered in the present Standard. A proposal of revision of the abovementioned Standard, in order to include also composite insulators, has been made by the Italian National Committee. Following the proposal IEC 78 demanded to WG 11 and to an ad hoc PT the revision of the Standard. In the following the available information derived from extensive experimental investigations performed is analyzed and discussed as a possible contribution to the foregoing revision. In particular the minimal requirements in case of composites are evaluated with the same methodology used for glass and porcelain insulators and then the methodology to detect the composite insulator defects of interest for LLW is discussed.

Progetti

Commenti