What Is A Transformer On A Power Pole？

Here's how it works:

High voltage input: Electricity travels long distances from power plants at high voltages (typically 7,200 to 34,500 volts) to reduce energy loss.
Voltage reduction: The pole transformer reduces this high voltage down to the standard 120/240 volts used in most homes in North America (or other local voltage levels depending on the country).
Distribution to homes: The lower-voltage electricity then flows through service wires to homes or buildings.

Primary winding: Receives high voltage.
Core: Magnetic core where voltage transformation happens.
Secondary winding: Outputs low voltage.
Tank: Metal housing filled with insulating oil to cool and insulate the transformer.
Bushings and terminals: Connect the transformer to overhead lines.