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11KV 1250KVA Three Phase Low Loss Distribution Transformer

11KV 1250KVA Three Phase Low Loss Distribution Transformer

The 11KV 1250KVA Three Phase Low Loss Distribution Transformer is meticulously engineered for modern power networks, offering exceptional voltage precision and energy conservation. Its innovative oil-immersed architecture combines high-grade oxygen-free copper windings with precision-rolled silicon steel cores to ensure uniform magnetic flux and superior performance under varying load conditions. The transformer’s fully sealed design and natural oil-cooling system provide robust thermal management and low maintenance requirements, making it ideally suited for both densely populated urban grids and heavy industrial installations. With reduced no-load and on-load losses, this transformer delivers consistent, high-quality power while supporting sustainable energy practices and long-term operational reliability.

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Product Accessories

Core (Magnetic Circuit System)
Material: Utilizes high-permeability cold-rolled silicon steel sheets (e.g., Baosteel Q series 0.23-0.30mm), employing a step-lap stacking process with fully oblique joints, significantly reducing no-load losses (S13 series achieves approximately a 30% reduction compared to S11 series).
Features:
Oil Tank Structure: Incorporates a fully sealed corrugated steel oil tank, eliminating the need for an oil conservator. This design compensates for oil volume expansion and contraction due to temperature changes through the corrugated structure, ensuring maintenance-free operation with a service life exceeding 30 years.

Windings (Electrical Circuit System)
High-Voltage Winding: The 11kV side employs a multi-layer cylindrical structure, wound with copper or aluminum conductors. Inter-turn insulation is provided by DMD insulation paper, enhancing mechanical strength and short-circuit resistance.
Low-Voltage Winding: The 0.4kV side features a copper foil winding structure, reducing eddy current losses and improving heat dissipation efficiency.
Insulation Process: Utilizes Vacuum Pressure Impregnation (VPI) combined with Class H insulation materials, capable of withstanding temperatures up to 180°C. The process includes vacuum oil injection to eliminate internal air bubbles, ensuring reliable insulation performance.

Oil Tank and Cooling System
Oil Tank Structure: Features a fully sealed corrugated steel plate oil tank that negates the need for an oil conservator. This design isolates the oil from oxygen and moisture, maintains an IP55 protection rating, and is suitable for harsh outdoor environments.
Cooling Method: Employs Natural Oil Immersion Cooling (ONAN), relying on the corrugated fins for efficient heat dissipation without the necessity for additional fans.

Protection Devices
Pressure Relief Valve: Automatically releases pressure when internal pressure reaches ≥35kPa, preventing oil tank rupture.
Gas Relay (Buchholz Relay): Monitors gases generated from internal faults, triggering alarms or tripping (standard for capacities of 800kVA and above).
Temperature Controller: Equipped with PT100 sensors, supports remote oil temperature monitoring. Models 800kVA and above come standard with a signal thermometer.

Tap Changer
No-Load Tap Changer (NLTC): Provides ±5% or ±2×2.5% voltage regulation on the high-voltage side, requiring de-energized operation, to adapt to grid voltage fluctuations.

Bushings and Terminal Connectors
High-Voltage Bushings: Made of porcelain or silicone rubber composite materials, with creepage distance ≥25mm/kV and anti-pollution flashover design.
Low-Voltage Terminals: Utilize tinned copper bars with anti-oxidation treatment, supporting high current connections.

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Product Specifications

Rated Voltage

Primary Side (High Voltage):11 kV

Secondary Side (Low Voltage):0.4 kV

Rated Power

1250KVA（1.25MVA）

No-Load Loss

≤1156–1200 W

Load Loss

≤12,000 W (at 75°C)

Short-Circuit Impedance

4.5% (Standard Value)

Vector Group

Dyn11 (High Voltage Delta / Low Voltage Wye with Neutral Point) or Yyn0

Cooling Method

ONAN (Oil-Immersed Natural Air Cooling)

Noise Level

≤52 dB (A-weighted sound pressure level at 1 meter from the transformer)

Insulation Level

Primary Side:Power Frequency Withstand Voltage: 35 kV for 1 minute

Secondary Side:Power Frequency Withstand Voltage: 5 kV for 1 minute

Standards Compliance

Meets IEC 60076 & ANSI requirements

Product Applications

Economy is more affordable

The 11KV 1250KVA transformer efficiently steps down high-voltage electricity for manufacturing facilities, ensuring stable and reliable power for heavy machinery and production lines.

Industrial Power Supply
Ideal for urban substations, this transformer distributes electricity to residential and commercial areas, maintaining consistent voltage levels amidst varying load demands.

Urban Power Distribution
Effectively connects renewable energy sources, such as solar or wind farms, to the grid, facilitating efficient energy transfer and supporting sustainable power initiatives.

Renewable Energy Integration
Provides uninterrupted and precise power supply to data centers, supporting critical IT infrastructure with minimal energy loss and optimal performance.

Data Center Operations

Product Advantages

Enhanced Energy Efficiency

Utilizing advanced oil-immersed technology, the transformer minimizes energy losses, contributing to reduced operational costs and improved energy conservation.

Robust and Durable Construction

Designed with high-quality materials and a sealed structure, it offers exceptional overload capacity and a lifespan exceeding 30 years with minimal maintenance requirements.

Flexible Voltage Regulation

Equipped with a no-load tap changer (NLTC), it allows for voltage adjustments of ±5% or ±2×2.5%, accommodating fluctuations in the power grid and ensuring stable voltage delivery.

WellDone Power Transformer Plan Drawing

FAQ

What range of transformer products do you offer and which standards do they meet?

We manufacture a diverse array of transformers including Oil-Immersed Distribution Transformers, Dry Type Transformers, Power Transformers, Three Phase Pad Mounted Transformers, Single Phase Pad Mounted Transformers, Substation Transformers, and Pole Mounted Transformers. Our technical team, with nearly 20 years of industry experience, ensures that our designs comply with international standards such as ANSI, IEEE, DOE, CSA, AS, AZS, GOST, IEC, and more. Additionally, many of our products have obtained UL, cUL, and CSA certifications, affirming their safety and performance in global markets.
How do you ensure the quality and reliability of your transformers?

Our transformers are produced under a rigorous quality management system covering every stage from material selection to final testing. Each product comes with a minimum 24-month warranty, ensuring long-term safety and reliability. This commitment to quality has earned the trust of global customers and leading industry players.
What are your production lead times, customization options, and global market reach?

For standard models, our production lead time is typically 10 to 25 days, and we offer flexible OEM/ODM services for customized projects. We also tailor packaging solutions to meet specific customer requirements. Our transformers are exported worldwide—including North America, Europe, South America, Australia, Asia, and Africa—with successful partnerships involving renowned companies. For more details or personalized support, please contact us via email or WhatsApp.