The 345kV three-phase oil-immersed power transformer is engineered for high-capacity transmission networks, utility substations, large power generation facilities, and major grid modernization projects. Designed for demanding extra-high-voltage applications, it provides reliable voltage transformation and efficient power transfer between generation sources and transmission systems.

345kV-class transformers are particularly associated with North American high-voltage transmission networks, making them an important solution for utility-scale grid reinforcement, renewable energy integration, regional transmission expansion, and replacement of aging substation equipment. Depending on the local transmission architecture and utility requirements, similar high-voltage applications can also be found in selected markets across Canada, the United States, Mexico, Chile, Brazil, Argentina, Australia, South Africa, China, India, Kazakhstan, Saudi Arabia, the United Arab Emirates and other countries developing large-scale transmission infrastructure.

• Maximum Capacity: Up to 500MVA, with higher ratings available subject to project requirements
• Voltage Class: 345kV, with customized system and insulation configurations
• Frequency: 50Hz / 60Hz
• Cooling: ONAN / ONAF / OFAF and other customized cooling arrangements
• Tap Changer: OLTC available for automatic voltage regulation and grid voltage control
• Design Life: More than 30 years under properly specified operating and maintenance conditions
• Delivery: Standard production schedule approximately 90 days; expedited manufacturing options available for selected urgent projects

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Product Advantages

High-Voltage Engineering & International Standards

Our 345kV power transformers are engineered for utility and industrial transmission applications and can be configured to meet the technical requirements of different countries, transmission operators, EPC contractors, and power generation projects.

• Applicable Standards: Designed according to relevant requirements of IEC, IEEE/ANSI, GB, GOST, EN and other applicable international or regional standards.
• North American Compatibility: Transformer design, accessories, protection systems, bushings and testing can be configured according to applicable North American utility and project specifications, including IEEE/ANSI-based requirements.
• Testing & Documentation: Factory testing, inspection records, technical documentation and project-specific test reports can be supplied according to the approved technical specification.
• Certification Support: ISO, CE, IEC, CSA, UL, SABS, COC and other relevant certification or compliance documentation can be supported where applicable to the destination market.

Key Product Advantages

Optimized for Extra-High-Voltage Transmission

At the 345kV level, transformer performance directly affects transmission reliability and substation availability. The transformer is designed with optimized magnetic circuits, high-strength windings and carefully coordinated insulation systems to withstand electrical, thermal and mechanical stresses during long-term operation.

The design can be customized according to short-circuit levels, insulation coordination, switching conditions, lightning exposure and utility-specific protection requirements.

High-Capacity Power Transfer

345kV transformers provide an efficient interface for transferring large amounts of electricity across regional transmission networks. They can be used for step-up applications at power plants, step-down applications at transmission substations, and interconnection projects between different transmission systems.

Large-capacity configurations are available for utility projects where power demand, transmission distance and network stability require robust transformer performance.

Renewable Energy Grid Integration

The rapid development of large-scale renewable energy requires high-voltage transmission infrastructure capable of moving electricity from remote generation sites to major load centers.

Our 345kV transformers can be configured for utility-scale solar PV, wind farms, hydropower, battery energy storage systems and hybrid renewable energy projects, supporting high-capacity renewable power evacuation and grid interconnection.

Built for North American Utility Applications

For projects in the United States and Canada, transformer configurations can be adapted to project-specific requirements related to 60Hz operation, utility protection schemes, transformer impedance, grounding arrangements, bushing interfaces, cooling systems and monitoring equipment.

This makes the 345kV transformer suitable for utility substation expansion, transmission corridor upgrades, renewable energy interconnection and replacement of aging high-voltage transformers.

Flexible Environmental Adaptation

Different transmission projects may be located in deserts, coastal regions, cold climates, high-altitude areas or industrial environments. The transformer can therefore be engineered with appropriate solutions for temperature extremes, high humidity, salt contamination, pollution, altitude and corrosive environments.

Optional measures include enhanced cooling, increased creepage distance, anti-corrosion treatment, customized sealing and specialized accessories for demanding site conditions.

Typical 345kV Application Markets

Because transmission voltage architectures differ between countries, the exact use of 345kV equipment should always be confirmed against the local utility grid code and project specification. Typical markets and regions where 345kV-class or comparable extra-high-voltage transmission equipment may be relevant include:

• North America: United States, Canada, Mexico
• South America: Brazil, Argentina, Chile, Peru and other countries expanding high-capacity transmission infrastructure
• Asia: China, India, Kazakhstan, Australia and selected Asian transmission markets
• Middle East: Saudi Arabia, United Arab Emirates, Oman, Qatar and other countries investing in large-scale generation and transmission systems
• Africa: South Africa, Egypt, Morocco, Algeria and other markets developing high-voltage transmission networks
• Other International Markets: Countries implementing renewable energy evacuation systems, regional interconnection projects and major transmission corridor upgrades

For projects outside North America, the transformer can be engineered to the actual system voltage and local standard rather than assuming that 345kV is the applicable nominal network voltage.

Why Choose HENGFENGYOU Electric for Your 345kV Projects?

A 345kV transformer is a critical asset in a transmission substation. Its design must balance electrical performance, thermal capability, mechanical strength, transport requirements, site conditions and long-term maintenance considerations.

Project-Specific Electrical Design

HENGFENGYOU Electric develops transformer configurations according to the actual requirements of each transmission project. Our engineers can evaluate rated capacity, system voltage, frequency, impedance, short-circuit current, insulation level, vector group, neutral grounding and tap range before finalizing the transformer design.

This project-based approach allows the transformer to be matched with the specific requirements of the transmission network rather than relying on a generic standard configuration.

Reliable Winding & Insulation System

For 345kV applications, the winding and insulation system is designed to withstand high electrical stress and repeated operating conditions. Optimized winding structures, high-quality insulating materials and controlled manufacturing processes contribute to stable dielectric performance and long-term service reliability.

Depending on the project, additional insulation and environmental measures can be incorporated for high-pollution, coastal, high-altitude or severe-weather locations.

Advanced Monitoring & Protection Options

To improve operational visibility and preventive maintenance, the transformer can be equipped with a range of monitoring and protection devices, including:

• Buchholz relay
• Pressure relief device
• Oil temperature and winding temperature indicators
• Oil level monitoring
• Online dissolved gas analysis (DGA) systems
• Bushing monitoring systems
• Cooling system monitoring
• Remote communication and condition-monitoring interfaces

The final configuration can be selected according to utility standards and the substation automation architecture.

Comprehensive Factory Acceptance Testing

Each 345kV transformer is subject to strict factory inspection and testing before shipment. Depending on the approved project specification, testing may include:

• Transformer ratio and phase displacement tests
• Winding resistance measurement
• No-load loss and excitation current tests
• Load loss and impedance voltage tests
• Insulation resistance and dielectric tests
• Induced voltage withstand test
• Separate-source AC withstand test
• Lightning impulse test
• Partial discharge measurement
• Temperature-rise test
• Auxiliary equipment and protection function checks

The complete FAT process provides customers with documented verification of the transformer's electrical, insulation and thermal performance before delivery.

Global Logistics & Technical Support

Large 345kV transformers require careful transportation planning because of their weight, dimensions and specialized lifting requirements. HENGFENGYOU Electric can coordinate technical documentation, packing, transportation planning, installation guidance and commissioning support for international projects.

From factory acceptance through site installation and operation, our technical team can provide project documentation and after-sales support to help customers maintain reliable transformer performance throughout the equipment lifecycle.

Ordering Instructions

For an accurate quotation and technical proposal, please provide the following project information:

• Transformer Rating: Rated capacity, primary/secondary voltage, frequency, vector group, impedance and tap range
• Electrical Requirements: System short-circuit level, insulation level, BIL/LI requirements, neutral grounding method and applicable utility standards
• Operating Conditions: Ambient temperature, altitude, humidity, pollution level, seismic conditions and installation environment
• Cooling Requirements: ONAN, ONAF, OFAF or other required cooling configuration
• Tap Changer: OLTC type, tap range, number of positions and control requirements
• Accessories & Monitoring: Bushings, conservator, Buchholz relay, temperature indicators, online monitoring, control cabinet and communication interfaces
• Customization: Oil type, transformer finish/color, enclosure requirements, cable interfaces and other project-specific options
• Quantity: Minimum order quantity is 1 set
• Standard Delivery: Approximately 90 days, subject to final technical configuration
• Expedited Delivery: Accelerated production and international delivery plans can be evaluated for urgent grid and renewable energy projects