The high voltage transformer series encompasses a full range of electromagnetic devices that transfer electrical energy between different voltage levels through electromagnetic induction. As the most critical equipment in power transmission and distribution networks, it enables efficient long-distance energy transmission and safe low-voltage power delivery to end users, serving utility grids, industrial plants and renewable energy projects worldwide.

High voltage transformers operate on the principle of mutual induction. An alternating current flowing through the primary winding generates a varying magnetic field in the iron core, which in turn induces an alternating voltage in the secondary winding. By adjusting the turn ratio between primary and secondary windings, the input voltage can be stepped up or stepped down to the required level while maintaining nearly constant power transfer. High-quality transformers achieve energy conversion efficiency above 98%, minimizing transmission losses across the grid.

The high voltage transformer series is mainly divided into two categories based on insulation and cooling methods. Oil-immersed transformers use mineral insulating oil as both insulation and cooling medium, with the core and windings fully immersed in a steel oil tank. They offer excellent heat dissipation performance, high overload capacity and relatively low cost, making them the mainstream choice for outdoor substations, solar and wind farm step-up stations, and industrial distribution systems. Common voltage ratings cover 10kV, 35kV, 110kV and above, with capacity ranging from tens of kVA to hundreds of MVA.

Dry-type transformers use epoxy resin or cast resin as insulation material, with no flammable oil inside. They are fire-resistant, pollution-free and produce low noise, and can be installed directly inside buildings without a dedicated fireproof oil sump. They are the preferred solution for indoor substations in high-rise buildings, shopping malls, hospitals, data centers and densely populated urban areas where fire safety is a top priority. Although their initial cost is higher than oil-immersed equivalents, they eliminate fire risk and reduce civil engineering costs for indoor installation.

When selecting from the high voltage transformer series, several core parameters require careful verification. First is rated capacity, which should be selected based on the total calculated load with a 15–25% margin for future expansion. Second is the voltage ratio and connection group, which must match the local grid standards and system phase requirements. Third is no-load loss and load loss — lower loss values reduce long-term operating costs and improve energy efficiency. Fourth is the insulation level and temperature rise class, which should be selected according to the installation environment and service life requirements.

Additional selection factors include cooling method, protection degree, tap changer configuration and monitoring functions. For renewable energy projects such as solar and wind farms, transformers with enhanced overload capacity and harmonic resistance are recommended to adapt to fluctuating power output. For indoor public places, dry-type transformers with F or H insulation class and low noise design should be prioritized.

We provide a complete high voltage transformer series including oil-immersed and dry-type models, covering 10kV to 220kV voltage levels and customizable capacity specifications. Contact our engineering team for technical parameter sheets, customized design and project quotation.