Pad-mounted transformers for distribution systems

10kva single phase transformer, generally used in the USA system, are attached to the overhead wires with two different types of connections:If a primary neutral wire is available, a 'wye' or 'phase to neutral' transformer can be used. This usually has only one bushing on top, connected to one of the primary phases. The other end of the primary winding is 'grounded' to the transformer's case, which is connected to the neutral wire of the 3 phase system, and also earth ground. Pad-mounted transformers have secure locked and bolted grounded metal enclosures to discourage unauthorized access to live internal parts. The enclosure may also include fuses, isolating switches, load-break bushings, and other accessories as described in technical standards. Pad-mounted transformers for distribution systems typically range from around 100 to 2000 kVA, although some larger units are also used.