The effect of moisture on the breakdown of aged oil in underground load interrupter switches

Breakdown tests on aged oil from underground load interrupter switches were conducted under various moisture conditions for different gap designs. Water drops, causing large electric field distortions, especially for uniform gap systems, showed the most adverse effect on the breakdown strength of oil. Dissolved water and fine droplets, with minor impact on breakdown strength, can result in dramatic increases in leakage current that may be used to detect the formation of large water drops and potential switch failures.<
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