EGYPTIAN EXPERIENCE OF LIVE LINE WASHING SYSTEM FOR 500KV OUTDOOR EQUIPMENT TO IMPROVE AVAILABILITY

摘要

It was a challenge for the Egyptian Electricity Holding Company (EEHC) to meet the continuoushigh growth rate of electricity demand, the peak demand increased from 3306MW to 23470MWduring the period 1980 /2010, and energy generated from 20 TWH to 139 TWH in the sameperiod. To meet this challenge, EEHC continuously adds annual achievements in the form ofconstruction of power plants.One of the big new power plants is the Nubaria power plant which was executed during the period2005 – 2009. The plant includes three combined cycle modules with total capacity of (3x750)MW. The 500KV air insulated switchgear ( AIS ) of the power plant is made up of 9 identicalbays for generator transformers which are interconnected to the 500kV network through twooverhead transmission lines, each is single circuit and to the 220kV network through two identicalthree single phase 500/220 kV auto transformers plus one phase as spare.As the External insulation of the 500, 220kV outdoor substations is exposed to salt- laden air anddesert dust, high salt content accumulates on insulators at times of high humidity and fogconditions, which can cause insulator flashovers, hence an extensive substation insulator washingprogram was necessary. The system is used regularly for washing the insulators of the outdoorequipment under tension by spray jet water nozzles permanently mounted on the switchyardequipment.This paper discusses the problem associated with the washing system of the 500kV outdoorcurrent transformers (CTs) in the above mentioned power plant. Different processes wererecommended as agreed between the manufacturers of the CTs and the live line washing system.