In modern power systems, High and Low Voltage Switchgear serves as the core equipment for power distribution, control, and protection. Acting as both the "nervous system" and the "safety guard" of the electrical grid, high and low voltage switchgear undertakes the critical functions of power transmission, distribution, and protection. From urban substations and factory production lines to the distribution rooms of large commercial centers, high and low voltage switchgear is ubiquitous.
At the same time, transformers – as the equipment that works most closely with switchgear – together form the complete power transmission and distribution chain. Whether it is an oil immersed transformer or a Dry transformer, both must be used in conjunction with high and low voltage switchgear to achieve reliable power transmission and safe distribution.
This article delves into the application scenarios of high and low voltage switchgear, analyzes the selection differences between oil immersed transformer vs cast resin, and introduces Xinhong Electrical’s professional solutions in the field of switchgear and transformers.
High and low voltage switchgear is a complete set of electrical equipment used to control and protect power devices in electrical systems. Its main role is to perform switching, control, and protection during power generation, transmission, distribution, and energy conversion. The internal components of switchgear include circuit breakers, disconnectors, load switches, operating mechanisms, instrument transformers, and various protective devices.
Complete high and low voltage electrical cabinets are the core hardware in industrial control, with their primary application being the foundation of the power and control systems for industrial automation. High-voltage switchgear can be used in factory main step‑down stations, large workshops, data centers, renewable energy sites (wind farms, photovoltaic stations), and more. Low-voltage switchgear is applicable to most power consumption scenarios, such as factory workshops, production lines, buildings, and infrastructure.
The structure of high and low voltage switchgear typically consists of the cabinet body, main busbar compartment, circuit breaker compartment (also known as the truck compartment), cable compartment, and relay instrument compartment. This modular design provides both high reliability and ease of maintenance and upgrading.
In power systems, high-voltage switchgear and transformers are inseparable. Transformers are responsible for voltage step‑up or step‑down, while switchgear handles power distribution, control, and protection. Together, they form the complete power transmission and distribution chain.
The oil immersed transformer is one of the most widely used transformer types in power systems. It uses mineral oil for cooling and paper insulation, offering superior cooling efficiency and heat dissipation, making it particularly suitable for high‑capacity applications. The global oil‑immersed transformer market was valued at approximately US$40 billion in 2025.
The oil immersed transformer China market continues to grow. As the world’s second‑largest economy, China’s oil‑immersed power transformer market is expected to reach about US$6.2 billion by 2032. Oil‑immersed transformers are widely used in power plants, substations, industrial and mining enterprises, etc., working in tandem with high and low voltage switchgear to achieve efficient power transmission and distribution.
A cast resin transformer uses epoxy resin to encapsulate the windings, providing high mechanical strength and moisture resistance. A cast resin dry type transformer eliminates the need for liquid insulation by encapsulating both primary and secondary windings in epoxy resin.
Dry transformers are widely used in locations with high fire safety requirements. Since dry transformers do not use flammable liquids, cast resin transformers do not spread flames, making them safer than mineral‑oil transformers in crowded areas. Cast resin transformers are commonly found in commercial buildings, industrial facilities, hospitals, airports, and other areas where fire risk and oil leakage are unacceptable.
In switchgear applications, dry transformers are specially designed for use with medium‑voltage switchgear and high‑voltage cabinets, with optimised dimensions that fully meet the installation requirements of high‑voltage switchgear.
When selecting transformers, the comparison between oil immersed transformer vs cast resin is a key decision for many projects. Both have their advantages and are suited to different application scenarios:
Advantages of Oil‑Immersed Transformers:
Higher cooling efficiency and superior heat dissipation, allowing higher power ratings and prolonged overload operation
Better suited for high‑capacity applications
Cost‑effective, especially in large‑capacity scenarios
Advantages of Cast Resin Transformers:
No liquid insulation, eliminating oil leakage risks
Simpler maintenance
More environmentally friendly, with lower environmental impact
Suitable for indoor installation without the need for fire suppression systems
Selection Recommendations:
For outdoor substations and large‑capacity industrial distribution, the oil immersed transformeris an ideal choice
For indoor distribution, commercial buildings, data centers, hospitals, and other locations with strict fire safety requirements, the cast resin transformer is more appropriate
Prefabricated substation manufacturers offer prefabricated substations, which represent a significant innovation in power equipment. These prefabricated substations change the traditional layout, civil construction, and installation methods of substations by manufacturing the entire system in the factory and installing it on‑site. They feature standardisation, modularity, and pre‑fabrication.
The prefabricated substation integrates high-voltage switchgear, transformers, and high and low voltage switchgear into a sealed enclosure, providing a “one‑stop delivery” of the substation’s core functions. All switchgear, primary and secondary equipment, along with the enclosure, are pre‑assembled and tested in the factory, ready for direct hoisting and installation on‑site.
This integrated solution is particularly suitable for:
Rapid construction of renewable energy plants (solar, wind)
Temporary power supply and emergency response
Power supply in remote areas and regions with weak grids
Distribution needs of industrial parks and commercial complexes
In power plants and substations, high and low voltage switchgear is the key equipment for power output. From the generator outlet to the step‑up station, and from high‑voltage transmission to low‑voltage distribution, switchgear runs through the entire power chain. High-voltage switchgearundertakes power distribution and protection at voltage levels of 10kV and above.
In factory workshops and production lines, high and low voltage switchgear provides stable and reliable power supply for various production equipment. From large metallurgical enterprises to precision electronics factories, switchgear works with transformers to ensure continuous production.
With the growth of the digital economy, data centers demand extremely high power reliability. Cast resin transformers – with no liquid insulation and excellent fire safety – are the ideal choice for data centers. High and low voltage switchgear provides advanced distribution functions such as dual‑supply and automatic transfer.
In wind farms, photovoltaic stations, and other renewable energy sites, switchgear is critical for power collection, step‑up, and grid connection. Oil immersed transformers and Dry transformersare flexibly selected according to project needs, working with switchgear as the electrical core of new‑energy plants.
From urban subways and airports to hospitals, schools, and commercial complexes, high and low voltage switchgear is widely used in various infrastructure projects. As the core equipment for power distribution, control, and protection, it underpins the power lifelines of cities.
Xinhong Electrical (Jiangsu Xinhong Electrical Equipment Co., Ltd.) is an enterprise integrating R&D, manufacturing, trade, and service, with a focus on industrial electrical equipment. The company’s main products include Dry transformers, oil immersed transformers, pad‑mounted transformers, prefabricated substations, power complete equipment, High and Low Voltage Switchgear, ring main units, and other power products.
Xinhong Electrical specialises in producing dry type transformers, oil immersed transformers, prefabricated substations, high and low voltage switchgear, ring main units, and more, widely used in various distribution projects. The company covers a total area of 28,000 m², employs 150 staff, and has passed the ISO9001 international quality management system certification.
As one of the oil immersed transformer manufacturers and prefabricated substation manufacturers, Xinhong Electrical is committed to providing customers with one‑stop power solutions – from transformers to switchgear, and from conventional substations to prefabricated substations. The company’s High and Low Voltage Switchgear series plays an essential role in switching, control, and protection in power systems.
Whether it is an oil immersed transformer or a cast resin transformer, a Dry transformer or an oil immersed transformer, Xinhong Electrical can provide the most suitable transformer and switchgear package based on each customer’s specific requirements.
High and low voltage switchgear, as the core of power systems, works together with transformersto form the foundation of modern power transmission and distribution. From oil immersed transformers to cast resin transformers, and from conventional substations to prefabricated substations, continuous technological advancement brings more choices to the power industry.
Xinhong Electrical will continue to deepen its expertise in high and low voltage switchgear and transformers, delivering reliable products and professional services to provide high‑quality power solutions for global customers, and contributing to the safe, stable, and efficient operation of power systems.
