Why is a transformer oil degasifier used during oil treatment?

A degasifier removes dissolved gases that reduce dielectric performance and can indicate evolving faults. During processing, vacuum degassing strips oxygen and nitrogen that can accelerate oxidation, and it helps remove fault gases that might be trapped after events like overheating or arcing. It also improves breakdown voltage and reduces the probability of partial discharge at sharp edges. Degassing is commonly combined with dehydration because moisture and gases interact, and both contribute to lower dielectric strength. For condition monitoring, degassing is controlled so it does not hide important diagnostic trends.