250kVA 500kVA Three Phase Oil Immersed Transformers

250kVA 500kVA Three Phase Oil Immersed Transformers

1. Product Description

250kVA and 500kVA three phase oil immersed transformers are mainstream medium-capacity three-phase distribution transformers widely deployed in municipal power grids, industrial parks and commercial power distribution systems. These energy-efficient oil-filled power transformers adopt mature industrial oil-immersed cooling technology and full copper winding structure, serving as core step-down power conversion equipment for medium and low voltage power distribution projects. Manufactured strictly in compliance with IEC 60076 and international power industry standards, both 250kVA and 500kVA three phase oil immersed transformers undergo full factory routine tests including insulation detection, loss calibration and short-circuit resistance testing to ensure stable and reliable long-term field operation.

Designed with standard Dyn11 vector group configuration, these low-loss three-phase oil immersed transformers effectively solve common power quality problems such as three-phase load imbalance, harmonic interference and zero-sequence current overload in conventional power distribution systems. Equipped with high-performance low-loss silicon steel core and high-purity oxygen-free copper coils, the transformers greatly reduce no-load loss and operational temperature rise during daily full-load and variable-load operation. Adopting fully sealed corrugated oil tank and ONAN natural oil cooling system, the internal insulating oil and core winding components are completely isolated from external dust, moisture and corrosive gases, effectively delaying insulation aging and avoiding oil leakage failure. Covering two conventional mainstream capacities of 250kVA and 500kVA, this series of oil immersed power transformers can flexibly match different load demands of industrial and municipal power distribution scenarios, with strong universality and high cost performance.

2. Technical Parameters

3. Core Purpose

The core purpose of 250kVA and 500kVA three phase oil immersed transformers is to provide stable, energy-saving and safe medium-voltage step-down conversion and power distribution for industrial and municipal three-phase power systems. As essential medium-capacity power transformation equipment in power grid terminals, these oil-filled three-phase transformers convert high medium-voltage grid power into standard 400V low-voltage industrial and civilian power supply, solving the voltage level mismatch between transmission lines and terminal power consumption equipment.

In actual power grid operation, these Dyn11 three-phase oil immersed transformers undertake key functions including three-phase load balancing, power quality optimization, grid voltage stabilization and circuit safety isolation. The 250kVA model is suitable for conventional medium-load power distribution, while the upgraded 500kVA capacity meets higher peak load and continuous full-load operation demands. Both models can effectively suppress grid harmonic interference, reduce zero-sequence current, avoid voltage deviation caused by unbalanced load, and ensure stable and qualified power supply for industrial production, commercial operation and residential centralized power consumption, helping power grids and enterprises reduce long-term operating energy consumption.

4. Application Scenarios

With reasonable capacity matching, stable operational performance and excellent outdoor environmental adaptability, 250kVA and 500kVA three phase oil immersed power transformers cover most mainstream medium-load three-phase power distribution scenarios. They are the preferred equipment for urban and rural grid renovation, industrial supporting, commercial power supply and new energy grid connection projects:

• Industrial Factory Power Distribution: The 250kVA and 500kVA three phase oil immersed transformers are widely used in small and medium-sized processing factories, mechanical manufacturing workshops, food processing plants and light industrial parks. They provide stable three-phase power for production lines, CNC equipment, mechanical operation systems and industrial auxiliary facilities, adapting to long-term continuous industrial power consumption.

• Urban & Rural Power Grid Renovation: Suitable for upgrading and capacity expansion of urban community power grids and rural medium-voltage power grids. They replace outdated high-loss old transformers, effectively improve regional power supply capacity, reduce grid operation loss, and solve the problems of insufficient power supply and unstable voltage in old residential areas and rural areas.

• Commercial Complex Power Supply: The 500kVA high-capacity model is ideal for shopping malls, large supermarkets, office buildings, hotels and community comprehensive service centers. It supports centralized power consumption of commercial lighting, central air conditioning, office equipment and public service facilities to ensure stable commercial operation.

• New Energy Power Station Grid Connection: Matched with distributed photovoltaic power stations, small wind power projects and energy storage systems. These three-phase oil immersed transformers complete stable voltage conversion and grid-connected power regulation for new energy power generation, optimize grid-connected power quality and avoid harmonic impact on public power grids.

• Infrastructure Engineering Supporting: Applied in highway service areas, railway supporting facilities, water conservancy projects, urban municipal engineering and scenic area infrastructure. They provide 24-hour stable and reliable power guarantee for public infrastructure and field engineering equipment.

• Residential Community Centralized Power Supply: The 250kVA model is suitable for ordinary residential clusters and suburban communities, while the 500kVA model matches high-density residential areas. Both ensure balanced three-phase power supply for household electricity, avoiding voltage fluctuation caused by concentrated peak power consumption.

5. Product Features

250kVA and 500kVA three phase oil immersed transformers adopt optimized low-loss design and mature oil-immersed manufacturing technology. With full copper winding configuration, Dyn11 balanced output and fully sealed anti-aging structure, they have obvious comprehensive advantages in energy saving, stability, safety and service life compared with traditional aluminum winding transformers, fully adapting to complex and changeable power grid operating conditions:

• High Energy-saving & Low Loss Performance: Adopting high-permeability low-loss silicon steel core and high-purity oxygen-free copper winding, the transformers effectively reduce no-load magnetic loss and load copper loss. All loss indicators meet international first-class energy efficiency standards, significantly reducing long-term grid operation energy consumption and enterprise electricity costs, with prominent energy-saving benefits.

• Dyn11 Balanced Three-phase Output: Standard Dyn11 vector group design realizes precise three-phase voltage and current balance, effectively inhibiting zero-sequence current and power grid harmonics. It can maintain stable voltage output under unbalanced load conditions, greatly improving terminal power quality and reducing equipment failure rate caused by power imbalance.

• Fully Sealed Leak-proof Structure: Integral welded corrugated oil tank structure with excellent overall sealing performance. It completely isolates internal core, windings and insulating oil from external humid air, dust and corrosive substances, preventing insulating oil aging, moisture ingress and insulation degradation, effectively solving the common oil leakage problem of traditional transformers.

• Stable ONAN Self-cooling System: Adopting oil natural circulation and air natural heat dissipation mode, the cooling is uniform and stable. It can effectively discharge internal heat generated by long-term full-load operation, avoid equipment overheating, and ensure continuous and stable operation of the transformer under variable load and peak load conditions.

• Strong Environmental Adaptability & Durability: The whole machine adopts heavy-duty anti-corrosion and weather-resistant spraying process, which resists ultraviolet aging, rain erosion, frost and snow damage. It can operate stably in high temperature, low temperature, high humidity and dusty harsh outdoor environments, supporting long-term unattended operation.

• High Safety & Low Maintenance Cost: Strict medium-voltage insulation design provides excellent lightning protection, over-voltage resistance and short-circuit impact resistance. The modular standardized structure simplifies daily inspection and maintenance work, with low failure rate and long service life, effectively reducing later operation and maintenance investment.

6. FAQ (Frequently Asked Questions)

Q1: How to choose between 250kVA and 500kVA three phase oil immersed transformers?

The selection of 250kVA and 500kVA three phase oil immersed transformers mainly depends on actual load demand and future capacity expansion plans. The 250kVA model is more suitable for small factories, ordinary residential communities and conventional medium-load municipal projects, with lower no-load loss and higher cost performance for daily stable load operation. The 500kVA high-capacity model is designed for scenarios with large power consumption, frequent peak load fluctuation and future capacity expansion demands, such as commercial complexes, medium-sized industrial parks and high-density residential areas. It has stronger overload resistance and load-bearing capacity, which can avoid equipment overload operation caused by load growth. Reasonable capacity matching can effectively balance power supply stability and long-term energy-saving benefits.

Q2: Are three phase oil immersed transformers suitable for long-term outdoor unattended operation?

Yes, 250kVA and 500kVA three phase oil immersed transformers are fully optimized for outdoor unattended working conditions. The fully sealed oil tank structure prevents internal insulation damp and insulating oil deterioration caused by long-term outdoor exposure. The weather-resistant and anti-corrosion shell can resist extreme weather such as high-temperature aging, low-temperature freezing, heavy rain erosion and wind-sand impact. The mature ONAN self-cooling system ensures stable heat dissipation under continuous full load, and the reinforced internal structure improves short-circuit and overload resistance. With reliable sealing and stable performance, both models can achieve 24-hour uninterrupted all-weather operation, fully meeting the long-term unattended operation requirements of outdoor substations and power grid terminals.

Q3: What routine maintenance do oil immersed three-phase transformers require?

250kVA and 500kVA three phase oil immersed transformers have low daily maintenance thresholds and stable long-term performance. Daily routine maintenance mainly includes visual inspection of oil tank welding seams and sealing points to check for oil leakage, and confirmation that insulating oil level and oil clarity are within the standard range. Operators need to regularly clean dust and sundries on the radiator surface to ensure unobstructed heat dissipation and prevent overheating faults under heavy load. It is necessary to periodically test winding insulation resistance and three-phase voltage balance, and check the tightness of high and low voltage wiring terminals. Long-term overload operation should be avoided in daily use. With standardized simple maintenance, the service life of the transformer can steadily reach more than 25 years.