The Corrosive Sulfur Test is used to detect corrosive sulfur compounds in transformer insulating oil that may react with copper components inside electrical equipment. In this test, a polished copper strip is immersed in an oil sample and heated under controlled conditions using the Huazheng HZ2831 Corrosive Sulfur Tester, after which the strip is inspected for discoloration or corrosion. The presence of dark or tarnished layers indicates corrosive sulfur in the oil. This test is important for evaluating the chemical stability of transformer oil, as corrosive sulfur can form copper sulfide deposits that may cause insulation failure and reduce the reliability of transformers.