275 KV Power Main Transformer

275kV Power Transformer Solution

I. 275kV Power Transformer Selection Scheme

The 275kV three‑phase oil‑immersed power transformer is core ultra‑high‑voltage equipment for national backbone transmission grids, large‑scale industrial bases, major renewable energy hubs, and large power plant main step‑up applications. It is designed for long‑distance bulk power transmission, voltage regulation, and efficient power distribution, with a maximum capacity of 500MVA. It has been operating reliably in over 50 countries worldwide. With 30 years of professional manufacturing experience, Hengfengyou Electric delivers a complete 275kV transformer solution compliant with global standards, featuring ultra‑high efficiency, long service life, and superior environmental adaptability.

1. Structure Type & Cooling Mode

• Mainstream Type: Three‑phase two‑winding / three‑winding oil‑immersed power transformer
• Capacity Range: 80MVA – 500MVA
• Cooling: OFAF, ODAF, ONAN/ONAF available
• Applications: Backbone grid substations, heavy industrial complexes, large wind/solar farms, metropolitan bulk supply substations, power plant main step‑up stations

2. Standards, Certifications & Energy Efficiency

• Standards: GB, IEC60076, GOST, EN, NF, ANSI/IEEE (customizable to client standards)
• Certifications: ISO, CE, IEC, SABS, COC, CSA, UL
• Efficiency: Efficiency >99.3%, compliant with EU 2015/2014/548/EC Ecodesign Tier 2
• Loss: Ultra‑low no‑load and load loss for long‑term energy saving and low‑carbon operation

3. Winding Structure Selection (Two‑Winding vs Three‑Winding)

• Two‑Winding Transformer: 275kV + one medium/low‑voltage winding; simple structure, lower cost
• Three‑Winding Transformer: 275kV + two medium/low‑voltage windings; multi‑voltage supply, higher reliability

4. On‑Load Tap Changer (OLTC) Selection

• MR (Germany): Ultra‑high reliability, mechanical life >200,000 operations, for backbone grid and flagship projects
• ABB: Balanced performance, global service network, smart grid compatible
• Huaming (China): Cost‑effective, fast after‑sales service, life ≈100,000 operations
• Principle: Imported brands for 275kV backbone grids and harsh environments; domestic brands for cost‑sensitive heavy industrial projects

5. Environmental Adaptability

• Enhanced ultra‑high‑voltage external insulation and heavy‑duty corrosion protection for high altitude, heavy pollution, coastal salt fog, and extreme temperatures
• Low noise, fire‑resistant design, enhanced heat dissipation for urban/indoor/underground 275kV substations
• Stable performance under severe fluctuating loads from large‑scale PV and wind farms

II. 275kV Transformer Design & Installation Scheme

1. Layout & Connection

• Preferred GIS/HGIS switchgear for compact layout, maximum safety and reliability
• Connected by gas‑oil bushing, GIB or ultra‑high‑voltage power cable
• Complies with strict N‑1 security criterion, supports single/parallel and grid interconnection operation

2. Key Installation Procedures

• Lifting & Placement: Heavy‑duty precision hoisting with qualified large crane
• Accessory Installation: Radiator, ultra‑high‑voltage bushing, conservator, cooling system, OLTC, surge arrester
• Vacuum Oil Filling & Hot Oil Circulation: Strict process to eliminate moisture and gas
• Standing & Venting: Stand ≥72 hours, repeated degassing and inspection
• Grounding: Neutral point, tank body, arrester combined reliable grounding; resistance ≤1Ω

3. Protection Configuration

• Premium zinc oxide lightning arrester on HV side
• CSP HV fuse / ultra‑high‑voltage circuit breaker
• Complete main and backup relay protection: differential, Buchholz, overcurrent, zero sequence, temperature, pressure, gas protection

III. 275kV Transformer Commissioning & O&M Scheme

1. Pre‑Commissioning Tests

• Winding DC resistance, ratio, polarity, vector group test
• Insulation resistance, applied voltage, induced withstand voltage test
• Partial discharge test (strict UHV standard for 275kV)
• Insulation oil test: breakdown voltage, moisture, DGA, furan analysis
• No‑load and load loss test to verify ultra‑high efficiency

2. System Commissioning

• Protection testing: differential and backup protection integrated linkage test
• 5 times no‑load impulse closing test
• On‑load test to verify protection polarity and metering accuracy
• Cooling system and OLTC full‑range linkage test

3. Intelligent O&M & Long Life Design

• Design life >40 years, actual life up to 50 years with professional maintenance
• Standard online monitoring: DGA, core grounding current, winding temperature, partial discharge, bushing monitoring
• Remote monitoring, condition‑based maintenance, intelligent early warning and alarm
• Life extension: control winding hot‑spot temperature ≤58℃, avoid long‑term overload, regular oil analysis and maintenance

4. Environmental Protection & Low Carbon

• FR3 biodegradable vegetable oil available, biodegradability >95%
• High‑proportion recyclable materials, low carbon footprint, aligned with global “dual carbon” goals

5. Delivery Time

• Standard model: 150 days
• Emergency order: 90 days fastest
• Custom model (special impedance, high altitude, special cooling): 7–10 months

IV. Core Specification Summary

V. Summary

Hengfengyou 275kV power main transformer leverages 30 years of ultra‑high‑voltage manufacturing experience, global top‑tier certifications, efficiency over 99.3%, service life over 40 years, and reliable delivery. It is widely applied in national backbone grids, heavy industrial groups, large renewable energy step‑up bases, regional core substations, and large power plants. The products operate reliably in over 50 countries including Tanzania, Zimbabwe, Ghana, South Africa, Kenya, Zambia, Sudan, Libya, Congo, UAE, Saudi Arabia, Iraq, Syria, Bangladesh, etc.

We adhere to standardized ultra‑high‑voltage design, modular precision manufacturing, intelligent O&M, and full life cycle service to provide customers with safe, reliable, energy‑saving and environmentally friendly 275kV power transmission and transformation solutions.

VI. 275KV Power Main Transformer FAQ

Q1: What is a 275kV power main transformer?
A: It is the core equipment of ultra‑high‑voltage transmission grids, used to step down 275kV to 110kV/35kV or step up medium voltage to 275kV for long‑distance bulk power transmission. Capacity range: 80MVA–500MVA. Components: core, winding, tank, heavy‑duty cooling system, ultra‑high‑voltage bushings, protection devices.

Q2: What are the main applications of 275kV transformers?

• Backbone grid hubs: connecting national and regional transmission networks
• Heavy industries: steel, chemical, mining, metallurgy
• Large renewable energy: utility‑scale PV and wind farm main step‑up
• Metropolitan core substations: bulk power supply for large cities
• Large power plant main step‑up stations

Q3: Difference between two‑winding and three‑winding 275kV transformers?

• Two‑winding: 275kV + one medium/low‑voltage winding; simple structure, lower cost
• Three‑winding: 275kV + two medium/low‑voltage windings; multi‑voltage supply, higher reliability, higher cost

Q4: How to choose OLTC brands: MR, ABB, Huaming?

• MR: >200k operations, highest reliability, for 275kV backbone grid projects
• ABB: balanced performance, global service network, smart grid compatible
• Huaming: cost‑effective, fast service, for heavy industrial projects
• Imported for backbone grids and harsh environments; domestic for cost‑sensitive industrial projects

Q5: What is the delivery time for 275kV transformers?

• Standard: 150 days
• Emergency: 90 days fastest
• Custom (high impedance, high altitude, special cooling): 7–10 months

Q6: What is the design life of 275kV transformers?

• Design life: >40 years (IEC ultra‑high‑voltage standard)
• Actual life: up to 50 years
• Key factors: load rate, maintenance, environment; control winding temp ≤58℃

Q7: What is the warranty term?

• Warranty: 24–36 months after delivery (per contract)
• Coverage: manufacturing defects
• Consumables (OLTC, bushings): usually 2‑year separate warranty
• Exclusions: man‑made damage, natural disasters, misuse

Q8: What after‑sales service is provided?

• Installation guidance, commissioning support, professional operation training
• Periodic maintenance: oil test, preventive test, condition assessment
• Emergency response: on‑site within 48 hours
• Upgrade: intelligent monitoring, capacity expansion, noise reduction

Q9: How to protect against lightning and short circuit?

• Install premium zinc oxide arresters
• Equip ultra‑high‑voltage CSP fuses or circuit breakers

• Reliable grounding system (≤1Ω)
• Complete main and backup relay protection system