The primary purpose of this test is to evaluate how solid materials—such as transformer board, pressboard, paper, plastic films, and varnishes—react when immersed in insulating oil under accelerated aging conditions. Over time, incompatible materials can dissolve into the oil, generate corrosive byproducts, or degrade the dielectric properties of the fluid.
The standard does not give a single "pass/fail" number. Instead, it instructs you to compare the aged oil properties against a blank oil sample (oil heated without the solid material). Key parameters to compare include: astm d3455 pdf