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Coating Porcelain Line Insulators to Prevent Pollution Flashover

March 16, 2019 • ARTICLE ARCHIVE, Insulators
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The Gulf State of Kuwait is nestled in one of the driest places on earth. A highly urbanized country, it is also one of the highest per capita consumers of energy, mostly for the oil and gas sector as well as for air conditioning and water desalination plants. Electricity demand peaks during the long dry summer when daily highs can reach 55ºC. There are also temperature fluctuations of as much as 25°C between day and night, which raise relative humidity and lead to frequent morning dew and even fog. Among the catalysts for flashover are frequent seasonal dust storms that result in rapid accumulation of pollution on porcelain insulators – especially along the country’s southern grid. T&D insulation coordination specialist, Raouf Znaidi reports on how maintenance and technical staff at Kuwait’s Ministry of Electricity & Water (MEW) implemented countermeasures to combat pollution flashover and enhance system reliability in an environment dominated by combinations of desert, industrial and marine pollution.


As of January 2018, the MEW network comprised 600 substations that connect 9931 circuit-km of overhead lines operating at 400 kV, 300 kV, 132 kV and 33 kV. This network runs along some 500 km of shoreline and also crosses a flat sandy desert to supply regional desalination plants as well as petroleum refineries and related petrochemical industries. Eng. Jassem M. Al-Nouri – Assistant Under Secretary in charge of the transmission network – explains that MEW produces, transmits and distributes electricity and water to serve the needs of an expanding urban population with one of the world’s highest per capita energy demands while also benefiting from among the lowest electricity prices. The power system in Kuwait serves a typical load profile dedicated mainly to extensive air conditioning (A/C) and water desalination. A/C systems alone account for nearly 70% of peak load and over 45% of total electricity consumption.

insulator Coating Porcelain Line Insulators to Prevent Pollution Flashover Pollution from Al Zoor Power Station combines with contaminants from nearby dry salt lake

Pollution from Al Zoor Power Station combines with contaminants from nearby dry salt lake.
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As annual demand grows rapidly, reports Al-Nouri, MEW faces challenges in aligning its strategic decisions to assure more consistent high quality service to citizens and other electricity users. Indeed, starting 2015, MEW management and technical staff in the electrical sector implemented an action plan to improve key performance indicators of the transmission and distribution system. The end goal is to keep the Kuwaiti network among the most reliable and with one of the lowest power outage rates – in spite of being exposed to severe pollution. Among the initiatives is one focused on predictive and preventive maintenance as well as remedial measures, the cornerstone of which is an ambitious program to apply RTV silicone coatings to improve pollution performance of installed porcelain long rods. This program is especially notable since it is the first in the GCC Region to feature live replacement using the latest generation of modified heavy Zoom line along with high-performance techniques in terms of lifting capacity and work speed.

Outdoor Insulation on MEW O/H Network

Eng. Fawaz Al Lanqawi – Director Under-Ground Cable and OHL Maintenance – states that MEW’s overhead system is insulated mainly using anti-fog type porcelain long rods. This applies to the entire 400 and 300 kV network and some 98% of the 132 and 33 kV systems, the balance being served by porcelain cap & pin strings.

To mitigate impact from deposition of contaminants as well as heavy wind loads, he explains that almost all lines in Kuwait are over-dimensioned, leading to unified specific creepage distances of as high as 65 and 63 mm/kV (according to the latest IEC 60815/TS) and to 320 kN and 230 kN minimum failing loads. Coupling size for 400 and 300 kV tension & suspension insulators are 24 mm and 20 mm respectively. Tables 1 and 2 summarize circuit lengths as well as insulation and technical characteristics of long rod insulators being used on each system.

insulator Coating Porcelain Line Insulators to Prevent Pollution Flashover Example of pollution deposition on anti fog profile porcelain long rod in Kuwait

Example of pollution deposition on anti-fog profile porcelain long rod in Kuwait.
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insulator Coating Porcelain Line Insulators to Prevent Pollution Flashover Screen Shot 2018 04 16 at 11

Table 1: Length & Insulation of Kuwaiti T&D System
* Type A* insulated with double 3 long rod insulators
** Type B** insulated with double 4 long rod insulators
*** with extension
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insulator Coating Porcelain Line Insulators to Prevent Pollution Flashover Technical Characteristics of Anti Fog Type Porcelain Long Rods

Table 2: Technical Characteristics of Anti-Fog Type Porcelain Long Rods. CLICK TO ENLARGE

 

1

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