345 kV 63-400 MVA High Voltage Power Transformer for Utility & Substation Applications

Manufactured by Yawei Transformer, the 345 kV High Voltage Power Transformer (63–400 MVA) is a utility-grade, oil-immersed power transformer designed for high-voltage transmission and substation applications. Engineered to operate reliably under extreme electrical, thermal, and environmental conditions, this transformer plays a critical role in modern power grids, including utility substations, transmission substations, and large-scale infrastructure projects.

With a strong focus on grid reliability, operational safety, and long service life, Yawei Transformer delivers high voltage power transformers that comply with ANSI, IEEE, and IEC standards, making them suitable for North American, European, and global utility markets. Our 345 kV transformer platform is designed to support both new transmission projects and grid modernization or capacity upgrade programs.

345 kV High Voltage Power Transformer Technical Specifications

Parameter	Specification
Rated Voltage	Up to 345 kV (design capability up to 500 kV)
Rated Capacity	63–400 MVA (full product range: 15–1200 MVA)
Transformer Type	High Voltage Power Transformer
Phase	Three-phase (single-phase available on request)
Cooling Method	ONAN / ONAF / OFAF (customizable)
Insulation System	Oil-immersed, full insulation design
Winding Configuration	Delta/Wye, Wye/Wye, or custom vector groups
Frequency	50 Hz / 60 Hz
Tap Changer	Off-circuit tap changer or OLTC
Standards	ANSI / IEEE / IEC
Installation	Outdoor, utility & transmission substations
Supply Mode	Factory direct, OEM / ODM

Designed for Modern Utility and Transmission Networks

The 345 kV high voltage power transformer is specifically developed to meet the increasing demands of high-capacity, long-distance power transmission. Utilities worldwide are facing higher load densities, renewable energy integration, and stricter efficiency requirements. Yawei Transformer addresses these challenges through optimized electromagnetic design, advanced insulation structures, and strict manufacturing control.

Typical applications include:

• Utility transmission substations

• Interconnection substations between regional grids

• High voltage nodes in national power networks

• Industrial substations with large power demand

• Renewable energy transmission corridors

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Advanced Full Insulation System and Low Partial Discharge Design

A key technical advantage of Yawei Transformer’s 345 kV series is its full insulation system design. By combining advanced electrical field simulation, optimized insulation structure layout, and precision manufacturing, our transformers achieve low partial discharge levels and high impulse withstand capability.

Key insulation features include:

• Optimized oil-paper insulation coordination

• Precision-formed pressboard components

• Uniform electric field distribution

• Reduced dielectric stress at critical points

This design significantly enhances long-term operational stability and reduces the risk of insulation aging, making the transformer ideal for ultra-high voltage and EHV transmission systems.

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Manufacturing Excellence and Factory Capability

As a professional high voltage power transformer manufacturer, Yawei Transformer operates advanced production facilities capable of manufacturing transformers up to 500 kV and 1200 MVA. From core stacking and winding to final assembly and testing, every stage is strictly controlled to ensure product consistency and quality.

Our factory capabilities include:

• Large-capacity core cutting and stacking lines

• Precision winding and insulation forming workshops

• Vacuum drying and oil filling systems

• Full routine, type, and special testing laboratories

Factory-direct manufacturing allows us to provide competitive wholesale pricing, stable delivery schedules, and full technical traceability.

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Custom Engineering for Global Standards

Each 345 kV power transformer can be customized to meet specific project and utility requirements. Yawei Transformer supports:

• ANSI / IEEE or IEC design standards

• Customized voltage ratios and impedance

• Special loss and noise level requirements

• Climatic adaptations for extreme environments

This flexibility enables us to serve U.S. utilities, European grid operators, EPC contractors, and international infrastructure projects.

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Landmark Case: China’s First 250 MVA / 345 kV Fully Insulated Transformer Exported to the United States

Yawei Transformer successfully developed China’s first fully insulated ultra-high voltage, large-capacity transformer rated at 250 MVA / 345 kV, marking a major milestone in domestic transformer technology.

This project simultaneously achieved:

• Large capacity (250 MVA)

• Ultra-high voltage level (345 kV)

• Fully insulated transformer architecture

The project covered the entire lifecycle, including design development, batch-production process engineering, and precision forming of transformer insulation structures. Yawei Transformer successfully mastered a complete proprietary technology system with independent intellectual property rights.

This achievement filled the domestic gap in 345 kV fully insulated, large-capacity, low-loss, low partial discharge intelligent transformers for export, and the unit was successfully transported and delivered to the United States, meeting stringent utility, testing, and logistics requirements.

International Project Experience and Global Supply

Beyond this landmark project, Yawei Transformer has supplied high voltage power transformers to multiple international markets, supporting:

• North American utility substations

• European transmission grid upgrades

• Southeast Asian infrastructure expansion

• Middle Eastern industrial power projects

Our experience in global logistics, compliance documentation, and on-site coordination ensures smooth project execution.

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Supporting the Full Range: 15–1200 MVA, Up to 500 kV

Yawei Transformer offers a complete portfolio of power transformers, covering:

• Voltage levels up to 500 kV

• Capacity range from 15 MVA to 1200 MVA

• Utility, transmission, and industrial applications

This allows customers to source single-unit solutions or complete transformer fleets from one trusted manufacturer.

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Quality Assurance and Testing

Every 345 kV transformer undergoes comprehensive testing, including:

• Routine tests

• Type tests

• Special tests (as required)

This ensures compliance with international standards and long-term operational reliability.

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Why Choose Yawei Transformer

• Proven experience in 345 kV and EHV transformers

• Independent intellectual property and proprietary technologies

• Factory-direct supply and wholesale pricing

• Strong U.S. and global project references

• Full lifecycle technical support

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Partner with Yawei Transformer

Whether you are a utility company, EPC contractor, or power infrastructure developer, Yawei Transformer provides reliable, efficient, and future-ready high voltage power transformer solutions.

From 63–400 MVA 345 kV transformers to custom 500 kV EHV systems, we help power grids operate safely and efficiently worldwide.