8-88/220 PRF 8-88/220 is a three-phase transformer manufactured by the Power Research Facility (PRF). It is an indoor, self-protected pad-mounted transformer with a weatherproof enclosure. It features an aluminum or copper winding, a built-in thermal cutoff device and a 13.33 kV voltage class. Its rated power is 2 MVA with a primary voltage of 13.33kV and a secondary voltage of 240/415V. The transformer has a top mounting, horizontal oil pipeline and a conservator tank. It also features a built-in secondary switch mounted near the tank and a built-in signal card installed inside the terminal box.