Power System 20MVA, 33kV/11kV, 50Hz/60Hz
Certifications IEC 62271-200, IEC 694, GB3906, DIN VDE 0670
Huajidian's 33kV 11kV 20mVA power transformer is a core power transmission and distribution equipment for medium- and high-voltage power grids. As a professional domestic power transformer manufacturer, Huajidian leverages years of R&D and production experience to optimize product structure and performance. Unlike small and medium-sized distribution transformers, this large-capacity equipment is primarily deployed in regional central substations, undertaking the core task of 33kV to 11kV step-down distribution. It is adaptable to complex power grid conditions, withstands long-term high-load operation and instantaneous short-circuit impacts, and is widely used in key projects such as urban power grid upgrades, industrial park infrastructure, and new energy grid connection distribution.
The product is ISO quality system certified, meets national energy efficiency standards, and features standardized manufacturing processes and rigorous quality control, meeting the construction and operation requirements of various high-standard substations.
1. Rated Capacity: 20MVA (20000kVA), suitable for medium to large regional power distribution load scenarios.
2. Voltage Level: 33kV on the high-voltage side, 11kV on the low-voltage side; the high-voltage side can be equipped with ±2×2.5% or ±5% off-load/on-load tap changers for flexible voltage adjustment to adapt to grid voltage fluctuations.
3. Phase and Frequency: Three-phase, 50Hz, compatible with domestic and international mainstream power grid standards.
4. Rated Current: Approximately 350A on the 33kV high-voltage side and approximately 1050A on the 11kV low-voltage side (calculated according to standard power formulas, with stable load bearing capacity).
Standard configuration Dyn11/YNd11, effectively suppressing grid harmonics, improving power supply quality, and providing reliable neutral grounding conditions for the low-voltage side; a mainstream configuration in modern power distribution systems.
7%-10%, customizable according to the substation's short-circuit capacity requirements, effectively limiting short-circuit current and ensuring the safety of the power grid and terminal equipment.
Meets the lightning impulse withstand voltage and power frequency withstand voltage standards for 33kV and 11kV systems. The lightning impulse withstand voltage on the 33kV side reaches 170kV, demonstrating excellent insulation and lightning protection performance, suitable for complex outdoor working conditions.
The product supports dual-mode heat dissipation to adapt to different loads and environmental conditions:
- ONAN Oil-Immersed Self-Cooling: Relies on natural convection of insulating oil and passive heat dissipation from the tank fins, suitable for conventional load scenarios, with low energy consumption and low noise.
- ONAF Oil-Immersed Air-Cooling: Combined with an external fan for forced air cooling, significantly improving the equipment's overload capacity and meeting the high-load power supply demands during peak electricity consumption periods.
The equipment core uses high-permeability silicon steel sheets or amorphous alloy low-loss materials, effectively reducing no-load and load losses, meeting national level I and II energy efficiency standards. The overall structure adopts a sealed and corrosion-resistant design, with a reinforced tank shell, suitable for complex scenarios such as indoor and outdoor installation, high altitude, and large temperature differences. The fully sealed oil circuit design prevents insulating oil aging and deterioration, significantly reducing later maintenance costs and ensuring long-term stable operation of the equipment.
The 33kV 11kV 20mVA power transformer is widely used in urban substations, industrial park distribution substations, new energy grid-connected substations, and municipal infrastructure power supply projects. It is suitable for medium to large load power supply scenarios such as densely populated urban residential areas, large industrial plants, airport and railway supporting power supply, wind and solar power station voltage conversion, and power grid upgrades.
Case Study: Brihart 33/11kV GIS Substation Project in Bangladesh
In the Brihart 33/11kV GIS substation EPC project of the Bangladesh power distribution system upgrade, Huadian customized and supplied a 33kV 11kV 20mVA power transformer as the core step-down equipment of the substation. Targeting the harsh environment of high temperature and humidity in the local area, the product has optimized its anti-corrosion, moisture-proof, and heat dissipation performance, and adopts ONAF air-cooling mode to ensure stable operation under continuous high loads.
After commissioning, the equipment successfully completed the conversion from 33kV high-voltage power to 11kV distribution voltage, resolving the issues of insufficient power supply capacity and unstable voltage in the Langpu area. This ensured power supply to surrounding industrial and residential areas, improved the reliability of the regional power grid by 30%, and has maintained stable operation with zero failures since commissioning, earning high praise from the owner and local power authorities.
With the continuous upgrading of power grid energy conservation and consumption reduction requirements, it is advisable to explicitly require equipment to meet national level I and II energy efficiency standards during procurement. Huadian products utilize low-loss iron cores and optimized winding designs, resulting in low operating energy consumption and effectively reducing long-term operating costs.
This model of large-capacity transformer is not readily available and must be customized based on the actual project conditions. Before procurement, key parameters such as installation method, altitude, ambient temperature, and system short-circuit capacity must be confirmed to ensure precise equipment compatibility.
This voltage level transformer requires the use of 33kV/11kV high-voltage switchgear, SF6 gas-insulated switchgear, GIS combined electrical equipment, and relay protection devices to form a complete power distribution system, ensuring the safe and compliant operation of the power grid.
Q1: Is this 33kV 11kV 20mVA power transformer suitable for outdoor high-altitude installation?
A1: Yes. Huajidian can customize the transformer according to the project's altitude and ambient temperature, upgrading it with high-altitude insulation reinforcement, UV resistance, corrosion and moisture protection features. It is suitable for outdoor open-air, high-altitude low-voltage environments and can withstand extreme weather conditions such as high temperatures, strong winds, and rainfall.
Q2: What is the difference between on-load tap changer and off-load tap changer configurations for this transformer?
A2: Off-load tap changers require de-energization for voltage adjustment, suitable for scenarios with stable grid voltage and low tap change frequency; on-load tap changers allow real-time voltage adjustment without de-energization and without affecting normal power supply, suitable for power grid projects with large voltage fluctuations and high power supply reliability requirements. Configuration can be selected as needed.
Q3: What is the equipment's lifespan and routine maintenance cycle?
A3: Under standard installation and normal operating conditions, the equipment's lifespan can reach 30 years. It is recommended to conduct routine maintenance annually, including insulating oil testing, equipment sealing checks, and line parameter calibration. The equipment adopts a fully sealed structure, resulting in low daily maintenance workload, low maintenance costs, and strong long-term operational stability.
As a professional high-voltage transformer manufacturer and service provider in China, Huajidian possesses complete production qualifications, advanced production equipment, and a professional technical team. We can provide global customers with one-stop services including parameter customization, drawing design, accurate quotations, on-site installation guidance, and after-sales maintenance. For substation project support needs, please feel free to contact us to obtain customized technical solutions and procurement quotations.
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