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AIS substations in Oman desert climate

A desert tale: protecting switchgear from sun, sand and salt

Petroleum Development Oman (PDO) is Oman’s largest producer of oil and gas. It accounts for more than 70 percent of the country's crude oil production and nearly all of its natural gas supply. PDO also operates a 132 kilovolt (kV) power transmission grid that feeds electricity to its production assets via a network of more than 3,000 kilometers of transmission lines and numerous high-voltage substations.

More than 20 of these high-voltage substations are equipped with air-insulated switchgear that controls, protects and isolates the electrical equipment in the substations.

Oman is a demanding environment for electrical equipment. Much of the country is desert, and the climate is hot and dry. Summer temperatures reach 50 degrees Celsius and monsoon winds from the Indian Ocean bring seasonal moisture and fog. It all adds up to a powerful mix of sun, sand and wind-borne salt, which pushes the robustness and durability of electrical equipment to the limit – and sometimes over the limit.

This is what happened to PDO. An increasing number of switchgear failures and flashovers – which in some instances led to blackouts – were traced to conductive contaminants on the porcelain insulators. They were caused by sea salt settling on the surface of the insulators and then dissolving in the moisture of the morning fog. Salt, water, dust and pollution on the surface of porcelain insulators create a conductive path that causes leakage currents and flashovers, and even blackouts.

PDO turned to ABB for a solution.

ABB replaced the high-voltage switchgear and porcelain insulators with new switchgear equipped with high-performance composite insulators and silicone rubber insulation.

Composite insulators with silicone rubber insulation are safer, lighter and offer superior pollution protection and insulation than porcelain. They protect the switchgear from conductive contaminants that can disable the porcelain insulators. The solution has proved to be highly successful and is now being deployed at all PDO’s 132 kV substations in Oman. This is being accomplished with minimal outages thanks to a standardized solution developed by ABB in close cooperation with PDO.

Main data

Refurbishment program ongoing
Rated voltage 132 kV
Material for insulators Composite
Temperature up to 50°C / 122°F
Pollution level
according IEC
very heavy
Connected distance 3000 km

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