12500 KVA Three-Phase Oil Immersed MV&HV Transformer 35kV to 10.5kV
1. Product Overview
The 12500 KVA Three-Phase Oil Immersed MV&HV Transformer 35kV to 10.5kV is a high-capacity, medium and high voltage power conversion device tailored for regional power grid step-down, industrial centralized power supply and new energy grid-connected projects. As a mainstream 12.5MVA class oil immersed power transformer, this equipment features a rated capacity of 12500kVA, a high-voltage primary input of 35kV and a low-voltage secondary output of 10.5kV, adopting mature three-phase double-winding structure and professional oil-immersed cooling and insulation technology. Strictly manufactured in accordance with IEC 60076 international standards and GB/T 6451 national power industry specifications, this 35kV step-down transformer delivers stable voltage conversion, excellent insulation performance and long-cycle continuous operation capability.
This MV&HV grade oil immersed transformer adopts high-grade grain-oriented silicon steel sheet core and high-purity copper winding coils, matched with fully sealed welded oil tank and multi-stage voltage regulation structure. It supports standard ONAN natural oil cooling and optional ONAF forced air cooling modes, adapting to different load rates and ambient temperature conditions. With a standard YN,d11 connection group and stable 8.0% short-circuit impedance, the equipment effectively solves the voltage grade conversion demand between 35kV medium-high voltage main grid and 10.5kV industrial distribution network, and is widely applied in urban power grid renovation, industrial park substations and new energy power generation supporting projects across the globe.
2. Core Product Features
2.1 Ultra-Low Loss & High Energy Efficiency
Optimized with 45° full inclined core lamination and staggered assembly technology, this 12500 KVA 35kV to 10.5kV oil immersed transformer effectively minimizes magnetic leakage and no-load loss. The no-load current is controlled below 0.4%, and the overall power conversion efficiency reaches over 99% under rated load. Compared with traditional old-model transformers, it reduces comprehensive operating power consumption significantly, fully meeting EU Eco Design Tier 2 and national energy-saving standards. The low-loss design cuts long-term grid operation costs for power stations and large industrial users, making it a high-efficiency energy-saving power transmission and distribution device.
2.2 Outstanding Short-Circuit Resistance & Structural Stability
The three-phase winding adopts integral reinforcement positioning and high-strength A-grade insulating material wrapping, with an optimized internal support structure to resist instantaneous short-circuit current impact and electromagnetic force deformation. The one-piece laser-cut steel tank and fully welded sealing process prevent external moisture, dust and corrosive gas from entering the internal cavity. The whole machine features extremely low partial discharge (controlled below 100pC), stable insulation performance and strong overload resistance, ensuring no structural deformation or insulation failure during long-term full-load and peak-load operation in complex power grid environments.
2.3 Flexible Voltage Regulation & Strong Grid Adaptability
Equipped with a ±3×2.5% off-circuit tap changer as standard, this 35kV MV&HV transformer supports multi-range high-voltage side voltage adjustment, which can effectively compensate grid voltage fluctuation and stabilize 10.5kV low-voltage output. It adapts to 50Hz standard power frequency operation, and can stably cope with unbalanced three-phase load, grid harmonic interference and seasonal voltage deviation. Whether for urban grid power supply with frequent load changes or new energy grid-connected scenarios with volatile power generation, the equipment can maintain consistent and reliable output voltage quality.
2.4 Low Noise & Excellent Environmental Adaptability
Through core vibration damping optimization and winding noise reduction design, the operating noise of the oil immersed transformer is controlled below 60dB under ONAN natural cooling status, far lower than industry standard limits. It can operate stably in the ambient temperature range of -40℃ to +45℃, and features good waterproof, rust-proof and aging resistance. The fully sealed oil tank structure avoids insulating oil deterioration and leakage, adapting to outdoor substation open-air installation, high-temperature humid areas and harsh industrial production environments without frequent maintenance.
2.5 Long Service Life & Low Comprehensive Maintenance Cost
Adopting high-temperature resistant insulating materials and anti-aging transformer oil, the equipment has a design service life of more than 30 years. The modular standardized structure simplifies daily inspection and maintenance work, with no need for frequent core lifting and internal overhaul. The stable mechanical and electrical performance greatly reduces equipment failure rate and later replacement cost, delivering excellent long-term cost performance for power grid operation and industrial power distribution projects.
3. Core Working Purposes
As a key core equipment for medium and high voltage power distribution systems, the 12500 KVA three-phase oil immersed MV&HV transformer undertakes the core task of step-down voltage conversion and safe power transmission. Its primary working purpose is to convert 35kV medium-high voltage electric energy from regional main power grids into standard 10.5kV medium-voltage electric energy, providing qualified power source for industrial production, regional power distribution and new energy grid-connected systems.
Beyond basic voltage transformation functions, this 35kV to 10.5kV power transformer also realizes high and low voltage electrical isolation, grid load balancing and voltage stabilization. It can effectively block high-voltage surge impact on low-voltage distribution equipment, improve the safety and stability of the entire power supply system, and reduce power transmission loss during energy distribution. For large-scale industrial enterprises and regional substations, it also supports peak load regulation, ensures continuous power supply during load fluctuation, and improves the overall operating efficiency of regional power grids.
4. Main Application Scenarios
4.1 Urban & Rural Regional Power Grid Substations
This 12500KVA high-capacity oil immersed transformer is widely used in 35kV grade urban central substations, township regional power supply stations and power grid renovation projects. It serves as the main step-down power transformation equipment for regional power grids, converting 35kV main grid power to 10.5kV distribution network power, covering residential living power, urban commercial power and public facility power supply, and supporting stable operation of urban and rural power distribution systems.
4.2 Large Industrial & Mining Enterprise Self-Use Substations
It is the preferred power transformation equipment for heavy industrial enterprises including metallurgy, chemical industry, building materials, mining and machinery manufacturing. Large industrial production lines and mining equipment have high continuous load demands, and this 35kV to 10.5kV MV&HV transformer can undertake the full factory centralized step-down power supply task, ensuring long-term stable and reliable power supply for high-power industrial equipment and avoiding production shutdown caused by voltage instability.
4.3 New Energy Power Station Supporting Projects
The equipment is perfectly matched for supporting power transformation of large-scale photovoltaic power stations, onshore wind farms and energy storage power stations. In new energy grid-connected systems, it completes step-down conversion of high-power new energy generation electric energy, solves the voltage matching problem between new energy units and public power grids, and realizes efficient consumption and safe grid connection of clean energy. It is an essential core device for medium and large-scale new energy power generation projects.
4.4 Industrial Park & Economic Zone Centralized Power Supply
Professional industrial parks, chemical parks and economic development zones have the characteristics of concentrated power consumption and high power supply stability requirements. This high-capacity oil immersed three-phase transformer can be used as the main power transformation unit of park centralized power supply substations, providing unified and stable 10.5kV medium-voltage power for multiple settled enterprises, realizing centralized power distribution and unified grid management, and improving the overall safety and economy of park power supply.
5. Frequently Asked Questions (FAQ)
Q1: What cooling modes are available for the 12500 KVA 35kV to 10.5kV oil immersed MV&HV transformer?
This transformer adopts ONAN natural oil circulation natural air cooling as the standard configuration, which features low operating noise, energy saving and stable heat dissipation, fully meeting the heat dissipation demand of long-term rated load operation under conventional ambient temperature. For projects with high load rate or high ambient temperature, optional ONAF natural oil circulation forced air cooling is available. The dual cooling mode design allows flexible switching according to on-site working conditions, effectively controls equipment temperature rise during peak load operation, and ensures safe and continuous operation of the transformer in all seasons.
Q2: What are the advantages of this 35kV grade oil immersed transformer compared with dry-type transformers of the same capacity?
Compared with same-capacity dry-type transformers, this oil immersed MV&HV transformer has obvious advantages in heat dissipation efficiency, overload capacity and cost performance. The insulating oil has excellent heat conduction and insulation performance, supporting long-term high-load operation and short-time overload impact. The fully sealed oil tank structure has better dust-proof, moisture-proof and anti-corrosion performance, suitable for outdoor substation installation and harsh industrial environments. Meanwhile, its manufacturing and later maintenance costs are lower, with a longer service life, making it more suitable for large-capacity, long-cycle continuous power supply scenarios such as regional substations and industrial self-use power stations.
Q3: How to adjust the output voltage when the on-site 35kV grid voltage fluctuates?
This 12500KVA three-phase transformer is equipped with a ±3×2.5% off-circuit tap changer as standard, which can realize multi-gear voltage regulation for the 35kV high-voltage side. When the on-site grid voltage is too high or too low, staff can adjust the tap gear in a power-off state to compensate grid voltage deviation and stabilize the 10.5kV low-voltage output. For scenarios with frequent grid voltage fluctuation, we can also customize on-load tap changer (OLTC) according to user demands, realizing uninterrupted dynamic voltage regulation and further improving the stability of terminal power supply.
