Pole mounted transformer parts

Pole mounted transformer parts

Transformers are critical components in the electrical distribution network, serving as devices that transfer electrical energy between two or more circuits through electromagnetic induction. Among the various types of transformers, pole mounted transformers stand out for their specific application and installation. Mounted on poles, these transformers are primarily used to step down the high voltage from utility lines to a lower voltage suitable for residential and light commercial use. This not only makes electricity more accessible but also safer for end-use applications.

Pole mounted transformers are a common sight in suburban and rural areas, where they become pivotal in bridging the gap between high-voltage transmission lines and the consumer. Their design and installation cater to the need for efficiency, safety, and reliability in power distribution.

Key pole mounted transformer parts

  • Tank: The tank houses the core and coils of the transformer, providing physical protection and helping in the cooling process. It is filled with insulating oil, which acts as a coolant and insulator, preventing overheating and electrical discharges. Additionally, the tank’s structure facilitates heat dissipation, improving efficiency, and its robust design ensures durability against weather, animals, and physical damage.
  • Core and Windings: At the heart of the transformer are the core and windings, where electromagnetic induction occurs. The core, made from high-permeability steel laminations, minimizes energy loss, while the windings, comprised of copper or aluminum coils, efficiently carry the electric current.
  • Insulating Oil: This oil serves dual purposes; it cools the transformer and provides electrical insulation for the internal components. Regular monitoring and maintenance are required to ensure its effectiveness and the overall health of the transformer. Beyond these roles, the oil prevents oxidation of internal components, and its quality is crucial for performance, necessitating periodic testing for dielectric strength, moisture content, and acidity.
  • Tap Changer: The tap changer allows for adjusting the transformer’s output voltage to compensate for varying loads or input voltage levels, crucial for a stable and consistent voltage supply. It can be manual or automatic, with automatic versions adjusting voltage in real-time for immediate response to load changes, enhancing electricity supply reliability.
  • Bushings: These insulated devices provide safe electrical connections between the transformer’s internal components and external power lines, preventing short circuits and leaks. Made with high-grade insulation materials and featuring grading rings, bushings distribute the electrical field evenly, reducing dielectric breakdown risk and ensuring operational reliability under high-voltage conditions.
  • Conservator Tank: Some single-phase pole mounted transformers include a conservator tank to hold excess insulating oil, accommodating volume changes due to temperature fluctuations. This tank is equipped with a diaphragm or bladder to separate oil from atmospheric air, preventing contamination and oxidation, thereby maintaining insulation quality and transformer efficiency.
  • Breather: The breather absorbs moisture, protecting the insulating oil from water vapor which can degrade its properties and cause transformer failure. It contains silica gel or other desiccants that change color when saturated, offering a visual maintenance indicator and thus reducing unexpected downtime and extending the transformer’s lifespan.

Use Cases of Pole-Mounted Transformers

  • Residential Areas: They step down the high voltage from utility lines to levels suitable for home appliances, ensuring safe and efficient power delivery to residential areas.
  • Rural Electrification: Their deployment is crucial in rural electrification, bringing electricity to remote areas where laying underground cables is not feasible or too expensive.
  • Street Lighting: Pole-mounted transformers are used to power street lights, providing the necessary voltage for lighting up roads and public spaces during the night.
  • Light Commercial Applications: Small businesses and light commercial facilities often rely on these transformers for their electricity needs, benefiting from the transformer’s ability to provide stable and reliable power.


Pole mounted transformers play an indispensable role in the electrical distribution network, making electricity accessible and safe for residential and light commercial use. By understanding the key components and their functions, one can appreciate the sophistication and efficiency of these devices. Their widespread use across various applications underscores their versatility and critical role in ensuring uninterrupted power supply, illuminating our homes, streets, and powering our daily lives. Through continuous innovation and maintenance, pole mounted transformers will continue to be a cornerstone of electrical distribution for years to come.

At TTES, we have over 100 combined years of experience manufacturing, maintaining, and repairing pole-mounted distribution transformers with various kva ratings. If you’re looking for industry-leading lead times of just 20 weeks on average, don’t hesitate and reach out to us for a free quote!

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