Technical Routes of Pad-Mounted Transformers
Pad-mounted transformers, as core equipment in medium and low-voltage power distribution systems, are widely used in urban residential areas, commercial centers, industrial parks and rural power grids due to their compact structure, safe operation and small floor space. With the acceleration of global urbanization, the promotion of smart grid construction and the increasing emphasis on energy efficiency and environmental protection, the technical routes of pad-mounted transformers are constantly evolving and innovating. Different technical routes have obvious differences in core principles, performance characteristics and application scenarios. The following will systematically elaborate on the main technical routes of pad-mounted transformers to provide a comprehensive reference for industry selection and technical research.
Oil-immersed pad-mounted transformers are the most traditional and widely used technical route. They use insulating oil as the main medium for insulation and heat dissipation, and their technical system has been optimized and upgraded for decades, with high maturity and reliability.
Insulation and heat dissipation mechanism: The transformer core and winding are immersed in insulating oil. The insulating oil not only isolates the internal components from the air to prevent moisture and dust intrusion but also absorbs the heat generated by the core and winding during operation. The heat is transferred to the tank wall through oil circulation and then dissipated to the surrounding environment through natural convection or forced cooling.
Structural design: The tank is usually made of corrosion-resistant steel plates, and the surface is treated with anti-rust coating to adapt to outdoor environments. For areas with harsh conditions (such as coastal areas with high salt spray), stainless steel tanks or special anti-corrosion coatings can be used to extend the service life.
Safety protection: Equipped with multiple protection devices, including pressure relief valves, oil level gauges, temperature sensors and gas relays. When the internal pressure of the tank exceeds the safe range due to faults (such as short circuits), the pressure relief valve will open automatically to prevent tank explosion. The gas relay can detect the gas generated by internal faults and trigger an alarm or cut-off signal in time.
This technical route is suitable for most outdoor power distribution scenarios, especially in areas with stable climate, sufficient installation space and low requirements for environmental protection (non-ecologically sensitive areas). It is widely used in rural power grids, suburban residential areas and industrial parks where the cost control is strict, as it has the advantages of low manufacturing cost and simple maintenance.
In recent years, in response to environmental protection requirements, oil-immersed pad-mounted transformers have gradually upgraded to environmentally friendly insulating oil (such as natural ester insulating oil) instead of traditional mineral oil. Natural ester insulating oil is biodegradable, non-toxic and has high fire resistance, which can reduce environmental pollution caused by oil leakage and improve the safety of the equipment.
Dry-type pad-mounted transformers are a technical route developed to meet the needs of environmental protection and safety. They do not use insulating oil but rely on air or solid insulating materials for insulation and heat dissipation, avoiding the risk of oil leakage and environmental pollution.
Insulation material and heat dissipation method: The winding is mainly insulated with glass fiber, epoxy resin or other solid materials. According to the heat dissipation method, it can be divided into two types: natural air-cooled (AN) and forced air-cooled (AF). The natural air-cooled type relies on the natural convection of air to dissipate heat, which is suitable for small-capacity transformers; the forced air-cooled type installs fans on the tank to enhance air flow, which can improve the overload capacity of the transformer and is suitable for medium and large-capacity scenarios.
Structural characteristics: The tank has good airtightness to prevent the entry of moisture, dust and small animals, ensuring the insulation performance of the winding. The core is made of high-quality silicon steel sheets with low loss, which can reduce the no-load loss of the transformer and improve energy efficiency.
Environmental adaptability: It has strong adaptability to harsh environments. It can operate normally in high temperature, high humidity, high dust and other environments, and does not need to set up oil storage pools (unlike oil-immersed transformers), which saves installation space and reduces engineering costs.
This technical route is the first choice for ecologically sensitive areas and densely populated places, such as urban central residential areas, hospitals, schools, shopping malls and chemical industrial parks. It is also widely used in subway stations, data centers and other places with high requirements for fire safety, as it has no risk of oil combustion and meets the strict fire protection standards.
Compared with oil-immersed pad-mounted transformers, dry-type pad-mounted transformers have obvious advantages in environmental protection and safety. They do not produce harmful substances during operation and use, and the solid insulating materials can be recycled, in line with the concept of circular economy. At the same time, their maintenance workload is smaller, and they do not need to regularly detect the oil quality and supplement insulating oil, which reduces the operation and maintenance cost.
With the development of smart grids, intelligent pad-mounted transformers have become a new technical route. They integrate digital sensing, communication and data analysis technologies on the basis of traditional oil-immersed or dry-type transformers, realizing real-time monitoring, remote control and intelligent diagnosis of the equipment.
Sensing and data collection module: Install multiple types of sensors inside and outside the transformer, including temperature sensors (monitoring the temperature of the core, winding and oil/air), current and voltage sensors (monitoring the load status), humidity sensors (monitoring the internal humidity of the tank) and partial discharge sensors (detecting potential insulation faults). These sensors collect operation data in real time and transmit it to the data processing unit.
Communication module: Adopt wired communication (such as Ethernet, RS485) or wireless communication (such as 4G/5G, LoRa, NB-IoT) technologies to connect the transformer with the upper-level monitoring platform (such as the power grid dispatch center or the enterprise operation and maintenance system). It supports the standard communication protocols (such as IEC 61850) to ensure the interoperability of data between different devices.
Intelligent analysis and control module: Use edge computing or cloud computing technology to analyze the collected data. It can realize functions such as load forecasting (predicting the load change trend according to historical data), fault diagnosis (identifying faults such as winding overheating and insulation aging through data anomaly analysis) and automatic control (adjusting the cooling system or triggering the protection device according to the operation status).
This technical route is mainly used in smart grid demonstration projects, new urban areas with high digitalization level and industrial parks with intelligent power management needs. For example, in smart communities, intelligent pad-mounted transformers can interact with smart meters, energy storage systems and distributed photovoltaic equipment to realize the optimal allocation of power resources and support the construction of "source-network-load-storage" integrated systems.
Intelligent pad-mounted transformers have changed the traditional "passive operation and maintenance" mode of transformers. Through real-time monitoring and predictive maintenance, they can reduce the probability of sudden faults and shorten the fault repair time, ensuring the reliability of power supply. At the same time, the operation data they provide can help power grid enterprises optimize the power distribution network planning and improve the overall efficiency of the power grid.
Compact integrated pad-mounted transformers are a technical route developed to meet the needs of limited installation space in urban areas. They integrate the transformer, switchgear, metering device and protection device into a single compact cabinet, realizing the miniaturization of the power distribution system and reducing the floor space.
Integration of functional modules: The cabinet is divided into multiple functional compartments (such as transformer compartment, switch compartment and metering compartment) according to the functional requirements. Each compartment is designed with independent insulation and protection measures to ensure the safety and reliability of the equipment. For example, the switch compartment is equipped with vacuum circuit breakers or load switches to realize the on-off control of the circuit; the metering compartment is equipped with smart meters to realize the accurate measurement of electric energy.
Space optimization: Adopt a three-dimensional layout to reduce the horizontal floor space. For example, the transformer is placed in the lower part of the cabinet, and the switchgear and metering device are placed in the upper part. At the same time, the size of the internal components is optimized (such as using low-loss and small-volume cores and windings), and the pipeline and wiring are simplified to further compress the cabinet volume.
Easy installation and maintenance: The cabinet is designed as a whole, which can be transported to the site as a single unit and installed quickly (only need to connect the incoming and outgoing cables). The compartments are equipped with detachable doors and observation windows, which facilitate the inspection and maintenance of internal components without disassembling the whole cabinet.
This technical route is especially suitable for urban central areas, old residential area reconstruction projects and road lighting power distribution systems where the installation space is limited. It is also widely used in temporary power supply scenarios (such as construction sites and temporary exhibition halls) because of its fast installation speed and high mobility.
Compared with the traditional "transformer + independent switchgear" mode, the compact integrated pad-mounted transformer can reduce the floor space by 30%-50%, save the land cost and simplify the on-site construction process. At the same time, the integrated design reduces the number of external connections, which can reduce the fault points caused by wiring errors and improve the overall reliability of the system.
Under the background of global carbon neutrality, low-loss and energy-saving pad-mounted transformers have become an important technical route to promote energy conservation and emission reduction in the power industry. They achieve the goal of reducing energy consumption by optimizing the core, winding and structural design.
Low-loss core material: Adopt high-grade non-oriented silicon steel sheets (such as 30Q130, 25Q120) with low iron loss. The silicon steel sheets have high magnetic permeability and low hysteresis loss, which can reduce the no-load loss of the transformer (the loss generated when the transformer is under no-load operation). Some advanced enterprises even use amorphous alloy materials to make the core. Amorphous alloy has extremely low no-load loss (only 1/3-1/5 of that of traditional silicon steel sheets), which is suitable for scenarios with long no-load operation time (such as rural power grids).
Optimized winding design: Use copper conductors with high conductivity instead of aluminum conductors to reduce the load loss (the loss generated when the transformer is under load operation). At the same time, optimize the winding structure (such as using a multi-layer cylindrical winding or a continuous winding) to reduce the winding resistance and leakage reactance, further reducing the load loss.
Efficient heat dissipation system: Optimize the tank structure and cooling device to improve the heat dissipation efficiency. For example, the oil-immersed type adopts a corrugated tank or a plate-type radiator to increase the heat dissipation area; the dry-type adopts a variable-frequency fan (the fan speed is adjusted according to the temperature) to reduce the power consumption of the cooling system.
This technical route is widely used in all types of power distribution systems, especially in areas with high electricity consumption and long operation time (such as industrial parks, commercial centers and large residential areas). It is also the key promotion product in the energy-saving transformation projects of existing power grids (such as the transformation of old transformers in rural areas and urban suburbs).
Many countries and regions have issued policies to promote the application of low-loss and energy-saving transformers. For example, China has formulated the national standard GB 20052-2020 "Limited Values of Energy Efficiency and Energy Efficiency Grades for Power Transformers", which classifies the energy efficiency of pad-mounted transformers into three grades (Level 1 is the highest) and prohibits the production and sale of transformers below Level 3. The European Union has also formulated strict energy efficiency standards (such as Ecodesign Directive) to promote the popularization of low-loss transformers. With the strengthening of global energy conservation policies, the market share of low-loss and energy-saving pad-mounted transformers will continue to increase.
The technical routes of pad-mounted transformers are diversified and differentiated, and each route has its own unique advantages and application scenarios. The oil-immersed type is suitable for traditional and cost-sensitive scenarios; the dry-type is suitable for environmentally friendly and safe scenarios; the intelligent type is suitable for digital and interactive scenarios; the compact integrated type is suitable for space-limited scenarios; and the low-loss energy-saving type is suitable for green and efficient scenarios.
With the continuous advancement of technologies such as new materials, digitalization and intelligence, the technical routes of pad-mounted transformers will further integrate and innovate. For example, the combination of "intelligent + low-loss" will become a mainstream direction, and the combination of "dry-type + compact integrated" will better meet the needs of urban smart power distribution. For enterprises in the industry, it is necessary to choose the appropriate technical route according to the market demand and application scenarios, and increase investment in technological research and development to promote the continuous upgrading of pad-mounted transformer technology and contribute to the construction of a green, efficient and intelligent power system.
I can further help you make a comparative table of technical routes of pad-mounted transformers, which will clearly show the differences in core features, application scenarios, advantages and disadvantages of each route, making it easier for you to quickly compare and select. Do you need this table?
