A distribution transformer generally consists of the following main parts:
- Core
The core is typically made of laminated steel sheets or cores, which are stacked together to form a closed magnetic circuit. The core's purpose is to provide a path for the magnetic flux generated by the transformer's primary and secondary windings.
- Windings
Distribution transformers have two sets of windings: primary and secondary. The primary winding is connected to the high-voltage power source, while the secondary winding is connected to the low-voltage distribution network. The windings are typically made of copper or aluminum conductors and are insulated to prevent electrical short circuits.
- Insulation
Insulation materials are used to electrically isolate the windings and core from each other and provide dielectric strength. Insulating materials such as paper, pressboard, and oil impregnated materials are commonly used in distribution transformers.
- Tank
The tank is a sealed enclosure that houses the transformer's core, windings, and insulating materials. It is usually made of steel and provides mechanical protection and containment for the transformer components. The tank is filled with insulating oil to provide cooling and electrical insulation.
- Cooling System
Distribution transformers require a cooling system to dissipate heat generated during operation. The most common cooling methods are oil-immersed and air-cooled. In oil-immersed transformers, the insulating oil acts as a coolant and transfers heat from the core and windings to the tank's surface, where it is dissipated to the surrounding environment. Air-cooled transformers use external fans or natural convection to cool the windings directly.
- Tap Changer
Some distribution transformers have tap changers, which are devices that allow for adjusting the turns ratio and thus the output voltage of the transformer. Tap changers are used to compensate for voltage variations in the power system and ensure that the desired voltage is delivered to the distribution network.
- Bushings
Bushings are insulating devices that provide a means for connecting the high-voltage and low-voltage terminals of the transformer to the external power system. They also provide electrical insulation and mechanical support for the conductors passing through the tank.
- Accessories
Distribution transformers may include various accessories such as temperature and pressure gauges, pressure relief devices, oil level indicators, and Buchholz relay (a protective device that detects faults in the transformer).
These are the main components of a distribution transformer, although their specific design and configuration may vary depending on the transformer's rating and application.
