The 20kV dry-type step-up transformer plays a vital role in modern solar photovoltaic (PV) power systems. It steps up the inverter output voltage from low voltage (typically 400V–1000V) to a 20kV medium-voltage level suitable for grid connection. With a compact structure, low loss design, and oil-free insulation, it ensures high efficiency, environmental safety, and long-term reliability across all types of solar power applications.
What Is a 20kV Dry-Type Step-Up Transformer?
A dry-type transformer operates without using insulating oil. Instead, the windings and magnetic core are encapsulated with epoxy resin, cooled through natural air (AN) or forced air (AF) circulation. As a step-up transformer, it boosts the inverter output to 20kV, enabling efficient energy transmission and grid integration. Its fire-safe, leak-free, and compact design makes it ideal for rooftop systems, containerized substations, and utility-scale PV stations.
Why Compact and Low-Loss Design Matters
High Efficiency: Advanced magnetic materials such as silicon steel and amorphous alloys minimize both no-load and load losses. This reduces heat generation, improves total system efficiency, and enhances overall power yield in PV systems.
Compact Structure: The absence of oil tanks and radiators allows for a smaller footprint and lighter weight, reducing installation costs and saving valuable space in containerized inverter stations and commercial rooftops.
Environmental Safety: Oil-free operation eliminates leakage and fire hazards, making it suitable for installations under strict environmental and fire protection standards.
Quiet Operation: Optimized core structure and resin-encapsulated windings minimize noise and vibration, ensuring smooth operation in residential or urban solar projects.
Typical Technical Specifications
| Parameter | Typical Value / Range |
| Primary Voltage | 20 kV |
| Secondary Voltage | 400V–1000V (customized) |
| Rated Capacity | 500–5000 kVA |
| Insulation Class | F or H Class (epoxy resin cast) |
| Cooling Method | AN (Air Natural) / AF (Air Forced) |
| Impedance Voltage | 4%–6% |
| Noise Level | Below 60 dB |
| Standard Compliance | IEC 60076-11, ANSI/IEEE, GB/T |
Applications in Solar PV Systems
The 20kV dry-type transformer is widely used in various renewable energy setups, including:
1. Utility-Scale Solar Farms: Used at inverter stations to step up low-voltage output to 20kV for efficient medium-voltage transmission.
2. Commercial Rooftop Systems: Compact and safe design enables installation in confined or indoor spaces where oil-filled transformers are unsuitable.
3. Hybrid Microgrids: Provides reliable power transformation in distributed energy systems that integrate solar, wind, and storage units.
Design and Installation Considerations
When designing a PV system, transformer capacity must be carefully matched with the inverter output while allowing room for expansion. Adequate ventilation is crucial to maintain cooling efficiency. Installation surfaces should be level and vibration-free, with proper grounding and overcurrent protection. Regular inspection of terminals, sensors, and ventilation ducts helps extend service life and ensures stable operation.
Key Benefits of 20kV Dry-Type Step-Up Transformers
1. Energy Efficiency: Reduced copper and core losses improve annual power yield and decrease heat-related degradation.
2. Fire Safety: Non-flammable resin insulation ensures compliance with IEC and building safety standards.
3. Minimal Maintenance: No oil handling, testing, or filtration required; simple cleaning and visual inspection suffice.
4. Eco-Friendly: Recyclable materials and zero oil contamination contribute to sustainable and clean power generation.
Standards and Certifications
Each transformer complies with IEC 60076-11 (Dry-Type Transformers), IEC 62271 (Medium-Voltage Equipment), and ISO 9001/14001 quality management systems. Factory acceptance tests, routine tests, and type tests guarantee its electrical, mechanical, and thermal performance under global standards.
Example Application
In a 50MW solar PV power plant, multiple 2500kVA 20kV dry-type step-up transformers are installed at inverter stations. Compared with traditional oil-filled models, power loss is reduced by 2.5%, resulting in higher annual energy yield and lower cooling energy consumption. The transformers are integrated into modular enclosures with smart temperature control, simplifying operation and maintenance.
Operation and Maintenance
Maintenance of dry-type transformers is simple and low-cost. Routine procedures include cleaning ventilation channels, checking electrical connections, and monitoring temperature sensors. Smart monitoring systems can log real-time temperature, voltage, and current data, enabling predictive maintenance that reduces downtime and operational risk.
Lifecycle Cost and Investment Value
Although initial purchase cost is higher than oil-immersed alternatives, the total cost of ownership (TCO) of dry-type transformers is significantly lower. Reduced power losses, maintenance-free operation, and extended service life make them a cost-effective and sustainable investment for solar developers and EPC contractors.
The 20kV dry-type step-up transformer offers unmatched efficiency, safety, and environmental performance for solar PV applications. With its compact design, oil-free insulation, and low energy loss, it supports clean and reliable power conversion in both utility-scale and distributed renewable systems. For long-term sustainability, safety, and energy optimization, this transformer remains the preferred choice for medium-voltage solar infrastructure.
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