What technical data is included in an oil filled transformer specification?

A specification typically includes kVA rating, primary and secondary voltages, frequency, vector group, impedance, cooling class, temperature rise, insulation levels, tap range and tap changer type, losses, efficiency, sound level, and short circuit withstand. For oil systems it includes oil type, oil volume, conservator or sealed tank design, breather type, expansion and pressure relief devices, radiators and fans, and instrumentation such as oil level, top oil temperature, winding temperature, and alarms. It also defines testing requirements, documentation, and environmental containment expectations.