HENGFENGYOU TRANSFORMER|ANSI/IEEE STANDARD TRANSFORMER
HENGFENGYOU TRANSFORMER|ANSI/IEEE STANDARD TRANSFORMER
The 345kV three‑phase oil‑immersed power transformer is critical ultra-high-voltage core equipment widely adopted in North American standard power grids, cross-state regional transmission networks, large-scale renewable energy delivery bases, heavy industrial power supply clusters and large utility power plant main step-up projects. Tailored for long-distance, large-capacity bulk power transmission and grid voltage stabilization of 345kV standard voltage class, the product features a maximum design capacity of 660MVA. With highly adaptable and stable operating performance, it has been successfully applied in numerous overseas grid and industrial energy projects. Backed by 30 years of UHV transformer R&D and precision manufacturing experience, Hengfengyou Electric provides full-set, customized 345kV power transformer solutions complying with mainstream international standards, characterized by ultra-low operational loss, extreme environmental adaptability, extended service life and smart grid compatibility.
Mainstream Type: Three‑phase two‑winding / three‑winding / auto-transformer oil‑immersed power transformer
Capacity Range: 150MVA – 660MVA
Cooling Mode: OFAF, ODAF, ONAN/ONAF optional, adaptive to full-load, continuous overload and peak-shaving operation conditions
Core Applications: North American standard 345kV backbone grid substations, cross-regional interconnection transmission hubs, large onshore/offshore wind farms and utility-scale solar power bases, heavy industrial clusters (metallurgy, chemical, mining, energy-intensive manufacturing), metropolitan large-capacity bulk supply substations, thermal power and new energy power plant main step-up stations
Compliance Standards: IEC60076, ANSI/IEEE C57 series (core applicable), GOST, EN, NF, GB 1094 series, fully customizable to meet client national grid specifications and project technical requirements
Authoritative Certifications: ISO quality management system certification, CE, IEC, SABS, COC, CSA, UL, fully meeting international project bidding qualification and grid access standards
Energy Efficiency & Loss Performance: Overall operational efficiency ≥99.45%, compliant with EU Ecodesign Tier 2 and North American grid energy-saving requirements. Adopts advanced low-loss silicon steel sheets and optimized electromagnetic circuit design, achieving ultra-low no-load loss and load loss, effectively reducing long-term grid operational energy consumption and supporting low-carbon power grid operation.
Two‑Winding Transformer: 345kV + single medium/low voltage winding; features simple structure, low failure rate and high cost performance, ideal for single-voltage large-capacity power transmission of independent power plants and single-load industrial energy bases
Three‑Winding Transformer: 345kV + two medium/low voltage windings; supports multi-voltage hierarchical power distribution, enhances grid power supply flexibility and operational redundancy, suitable for multi-load composite substations and regional power dispatch hubs
Auto‑Transformer: Compact optimized structure, light weight, low operational loss and high transmission efficiency, specially designed for 345kV regional grid interconnection and cross-voltage level power transmission and distribution projects
MR (Germany): Ultra-high operational reliability, mechanical service life exceeding 200,000 switching cycles, stable performance under long-term heavy load and frequent voltage regulation, prioritized for core 345kV backbone grid projects and harsh extreme working conditions
ABB: Balanced comprehensive performance, mature global after-sales service network, excellent smart grid compatibility and remote intelligent regulation capability, suitable for international EPC projects and urban core power grid construction
Huaming (China): High cost performance and rapid on-site after-sales response, with a mechanical service life of approximately 100,000 operations, perfect for cost-controlled heavy industrial power supply and conventional regional substation projects
Selection Principle: Imported OLTC brands are recommended for 345kV main backbone grids, cross-regional transmission and extreme environment projects; high-quality domestic brands are adopted for industrial supporting and conventional projects to balance overall performance and project economy.
Equipped with enhanced UHV external insulation system and heavy-duty multi-layer anti-corrosion coating, capable of stable operation in high altitude areas, severe industrial pollution zones, coastal heavy salt fog environments and extreme high/low temperature conditions. Adopts optimized low-noise structural design and integrated fire-resistant & explosion-proof configuration, complying with operational standards for urban built-in, indoor and underground 345kV substations. It features strong anti-fluctuation load capacity, which can adapt to unstable power output of large-scale wind and solar centralized bases, maintaining stable electrical parameters under long-term fluctuating load operation.
Adopts matched GIS/HGIS fully enclosed switchgear to realize compact station layout, reduce floor occupancy and improve overall operational safety and electromagnetic anti-interference capability. Main equipment connections adopt high-reliability gas-oil bushings, GIB closed busbars or UHV special power cables. The entire system strictly follows grid N‑1 safety criteria, supporting single-unit independent operation, multi-unit parallel operation and regional grid interconnection to ensure continuous and stable power supply of the whole system.
Lifting & Placement: Deploy qualified large professional cranes for precise heavy-duty hoisting and positioning, strictly control horizontal deviation and installation precision to avoid structural stress deformation of equipment.
Accessory Installation: Complete standardized installation and commissioning of radiators, 345kV ultra-high voltage bushings, oil conservators, forced cooling systems, on-load tap changers and surge arresters to ensure tight and firm connection of all components.
Vacuum Oil Filling & Hot Oil Circulation: Implement strict vacuum degassing and constant-temperature hot oil circulation process to completely remove internal moisture and residual gas, guaranteeing excellent insulation performance of transformer oil and internal insulation structure.
Standing & Venting: After oil filling, the equipment stands for no less than 96 hours, with repeated degassing and multi-index inspection to eliminate hidden risks of internal air bubbles.
Grounding Construction: Adopt integrated reliable grounding design for neutral point, tank body and arrester, with grounding resistance strictly controlled ≤1Ω, meeting UHV equipment safety operation specifications.
High-performance zinc oxide lightning arresters are installed on the high-voltage side to resist lightning surge and overvoltage impact. Matched with dedicated 345kV CSP high-voltage fuses and UHV circuit breakers for rapid fault isolation. Equipped with complete main and backup relay protection systems, including differential protection, Buchholz gas protection, overcurrent protection, zero-sequence protection, temperature protection, pressure protection and gas linkage protection, realizing full-coverage fault monitoring and automatic safety protection.
Conduct comprehensive factory and on-site pre-commissioning tests in accordance with ANSI/IEEE and IEC UHV unified standards, including winding DC resistance test, voltage ratio test, polarity and vector group verification. Complete insulation resistance test, power frequency applied voltage test and induced withstand voltage test to verify internal insulation strength. Carry out high-standard partial discharge test exclusive for 345kV UHV equipment to eliminate partial discharge hidden dangers. Perform full-index insulation oil detection covering breakdown voltage, moisture content, DGA dissolved gas analysis and furan component analysis. Complete no-load loss and load loss tests to verify the equipment’s ultra-high energy efficiency performance.
Implement integrated linkage test of differential protection and backup protection to ensure accurate and reliable protection action. Complete 5 times no-load impulse closing tests to verify equipment impact resistance and insulation stability. Conduct on-load trial operation to calibrate protection polarity and metering accuracy. Perform full-range linkage debugging of cooling system and OLTC to ensure flexible switching and stable operation of all functional modules.
The equipment adopts long-life optimized design, with standard design life ≥40 years, and the actual service life can reach 50 years under standardized professional maintenance. Equipped with standard online intelligent monitoring system, covering DGA dissolved gas online monitoring, core grounding current monitoring, real-time winding temperature monitoring, online partial discharge detection and bushing operating status monitoring. Supports remote data transmission, condition-based maintenance, intelligent early warning and fault alarm functions. Core life extension measures: strictly control winding hot-spot temperature ≤58℃, avoid long-term overload operation, and carry out regular oil sampling analysis and standardized preventive maintenance.
Optional FR3 biodegradable vegetable insulating oil with a biodegradability rate over 95%, which is green, pollution-free and free of environmental leakage risks. The equipment adopts a high proportion of recyclable metal and insulating materials, with low full-life-cycle carbon emissions, fully adapting to global dual-carbon strategic goals and green smart grid construction requirements.
Standard Model: 180 days production and delivery cycle
Emergency Order: Fastest 120 days delivery
Custom Special Model: Special impedance, high altitude anti-icing, heavy corrosion protection, special cooling configuration, 8–12 months delivery cycle
| Item | Core Content | Recommended Scheme/Standard |
| Type | 345kV three‑phase oil‑immersed power main transformer | Two/three-winding/auto-transformer, 150MVA–660MVA |
| Standards | Global ultra‑high‑voltage universal standards | ANSI/IEEE/IEC/GOST/EN/GB, compliant with international grid energy efficiency standards |
| Efficiency | Ultra‑high efficiency, ultra‑low loss | ≥99.45%, EU Tier 2 & North American grid energy efficiency standard |
| Life | Extra‑long life design | Design life ≥40 years, actual life up to 50 years |
| Eco | Green insulation & low carbon | FR3 vegetable oil optional, biodegradability >95% |
| Cooling | Heavy‑duty cooling modes | OFAF/ODAF/ONAN/ONAF adaptive matching |
| OLTC | Premium brand options | MR, ABB, Huaming (classified selection by scenario) |
| Grounding | Ultra‑high‑voltage safety grounding | Grounding resistance ≤1Ω |
| Delivery | Reliable lead time | Standard 180d, fastest 120d, customized 8–12 months |
Hengfengyou 345kV power main transformer leverages 30 years of professional UHV transformer manufacturing experience, global top-tier certification system, ultra-high energy efficiency and super-long service life design. Optimized for American-standard power grids and international mainstream UHV projects, this product boasts outstanding environmental adaptability and stable operational performance. It is widely applied in 345kV backbone grid projects, cross-regional power transmission interconnection projects, large-scale new energy delivery bases, heavy industrial power supply clusters, urban core bulk supply substations and large power plant main step-up stations worldwide.
Our 345kV series transformers have achieved stable and reliable operation in multiple countries and regions in North America, Africa, the Middle East and Southeast Asia, maintaining zero major failure records for key grid projects. We adhere to standardized UHV structural design, modular precision manufacturing, full-life-cycle intelligent O&M and one-stop customized services, providing global clients with safe, reliable, energy-saving and eco-friendly integrated 345kV power transmission and transformation solutions.
Q1: What is a 345kV power main transformer?
A: As the core UHV equipment for American-standard and international 345kV level power transmission grids, it is mainly used for stepping down 345kV ultra-high voltage power to 110kV/35kV medium and low voltage for regional power distribution, or stepping up medium-voltage power generated by power plants and new energy bases to 345kV for long-distance, large-capacity grid-connected power transmission. Its capacity range covers 150MVA–660MVA. The core structure consists of high-performance low-loss iron core, multi-layer insulated winding, fully sealed fuel tank, heavy-duty cooling system, UHV insulation bushings and complete safety protection devices.
Q2: What are the main applications of 345kV transformers?
- Standard 345kV backbone grid hubs: Core equipment for North American standard cross-state and regional transmission network interconnection
- Heavy industrial power supply: Supporting large-scale steel, chemical, mining and energy-intensive industrial bases
- Large new energy bases: Main step-up equipment for utility-scale onshore and offshore wind farms and photovoltaic power stations
- Urban power supply core: Large-capacity bulk power supply for super-large urban central substations
- Large power plants: Main step-up stations for thermal power, hydropower and centralized new energy power plants
Q3: Difference between two‑winding, three‑winding and auto 345kV transformers?
Two‑winding: 345kV + single medium/low voltage winding; simple structure, low failure rate and high cost performance, suitable for single-scenario large-capacity power transmission
Three‑winding: 345kV + two medium/low voltage windings; supports dual-channel multi-voltage power supply, flexible grid scheduling and high operational reliability with moderate cost
Auto-transformer: Compact integrated structure, small floor area, low operational loss and high transmission efficiency, specially applicable to 345kV grid interconnection and cross-voltage level power transmission projects
Q4: How to choose OLTC brands: MR, ABB, Huaming?
MR: 200,000+ switching service life, top-level reliability, preferred for core 345kV backbone grids, cross-regional transmission and harsh working condition projects
ABB: Balanced comprehensive performance, global service network and smart grid compatibility, ideal for international EPC and urban core grid projects
Huaming: High cost performance and rapid after-sales response, suitable for cost-sensitive industrial supporting and conventional substation projects
Selection rule: Imported brands for key backbone grid projects; high-quality domestic brands for conventional industrial and regional grid projects to balance performance and economy.
Q5: What is the delivery time for 345kV transformers?
- Standard model: 180 days
- Emergency order: Fastest 120 days
- Custom special model (high altitude, anti-corrosion, special impedance, special cooling): 8–12 months
Q6: What is the design life of 345kV transformers?
- Standard design life: ≥40 years (IEC & ANSI/IEEE UHV standard)
- Actual service life: Up to 50 years under standardized intelligent maintenance
- Core influencing factors: Operating load rate, ambient environment and daily maintenance quality; core control index: winding hot-spot temperature ≤58℃
Q7: What is the warranty term?
- Basic warranty period: 24–36 months after delivery (negotiable per formal contract)
- Warranty coverage: All manufacturing quality defects
- Independent warranty for consumable parts (OLTC, UHV bushings): 2 years
- Exclusions: Man-made damage, force majeure natural disasters and improper operation & maintenance
Q8: What after‑sales service is provided?
- On-site installation guidance and full-process commissioning technical support
- Professional operational and maintenance personnel technical training
- Regular periodic maintenance, oil testing and preventive performance inspection
- Global emergency response: On-site service within 48 hours for overseas projects
- Upgrade services: Intelligent monitoring transformation, capacity expansion optimization, noise reduction and energy-saving renovation
Q9: How to protect against lightning and short circuit for 345kV transformers?
- Equip high-performance zinc oxide lightning arresters on HV side to resist overvoltage and lightning surge impact
- Match dedicated 345kV CSP high-voltage fuse and UHV circuit breaker for rapid fault isolation
- Build integrated reliable grounding system with grounding resistance ≤1Ω
- Deploy complete main and backup relay protection system to realize full-coverage fault early warning and automatic protection tripping
