Abstract: Power transformers (PTs) are important electrical equipment in power plants and substations. A potential fault of the PTs leads to a power outage, a threat of electricity supply, as well as accelerating economic losses and environmental problems. Therefore, one of the basic problems to ensure the operational safety of the PTs is to monitor and diagnose the condition of the equipment, which assures the ability to initial detect the development of defects. From the early 2000s up to now, there have been dozens of reports of sulfur corrosion in PTs and related failures. However, research and monitoring of sulfur corrosion in transformers in the Vietnamese power grid have merely begun to be performed at a limited extent. This article presents an overview of research results on sulfur corrosion in transformers and the observation status of transformers in operation in Vietnam.

Keywords: Insulating oil, insulation paper, copper sulfide, corrosive sulfur, dibenzyl disulfide