When performing preventive maintenance on an oil-immersed transformer, it's good to know what kind of problem you're looking for. Oil-immersed transformers have some common operational problems. Understanding what these are and how they manifest themselves can help you identify any signs of impending failure. You can then stop the failure before it starts, which saves money and reduces unplanned downtime.
Here are some standard questions that can tell you when to repair or replace a transformer:
Presence of sludge: Sludge formation is caused by chemical reactions such as polymerization and decomposition, which produce solids that accumulate in the winding structure. Moisture can also cause oxidation and deterioration of the oil.
Signs of aging: Signs of aging such as aging insulation can be clues to the overall condition of the machine. Components wear out naturally and require more maintenance over time, so it's a good idea to consider upgrading your system.
Oil Leaks: Oil leaks can come from gaskets, cooling radiators/fins, tanks, gaskets, and various other transformer components. If they are small and do not occur often, they can be fixed, but if they occur frequently, they indicate a bigger problem.
Radiator clogging: When you photograph the radiator clogged or turned off with an infrared camera, the radiator will appear cold. If your heatsink has this problem, solve it as soon as possible. If the operating temperature of the transformer increases by 46.4 to 50 degrees Fahrenheit, its life will be cut in half. This is because the material of the insulating windings and structures begins to degrade.
Mineral deposits: Avoid water ingress into transformer tanks or radiators. These minerals will form deposits on the surface of these parts and are extremely difficult to remove. These can also reduce the efficiency of the cooling system, making your equipment more prone to overheating and failure.
Electrical failures: Electrical problems are often a common cause of transformer failures. They can be triggered by line faults and voltage spikes. A high-quality surge protection system can prevent this from happening.
Paper degradation: When cellulose paper ages, it releases furans that accumulate in oil, resulting in sludge. This process can be faster if the paper is exposed to contaminants, which is why a tight seal is required.