An oil type transformer specification defines electrical ratings and oil system requirements. It typically includes power rating, voltage ratio, vector group, impedance, insulation level, temperature rise limits, and tap changer details. On the oil side it specifies oil type and standard compliance, oil volume, dielectric and moisture limits, cooling class (ONAN, ONAF, OFAF), sealing system, conservator design, breathers, pressure relief, and oil sampling provisions. It also includes acceptance tests, oil test requirements, accessories such as gauges and alarms, and environmental requirements like secondary containment for spill control at the installation site.
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