66 KV Power Main Transformer

66kV Power Transformer Solution

I. 66kV Power Transformer Selection Scheme

The 66kV three-phase oil-immersed power transformer is a core high-voltage equipment for regional power grids, industrial power supply, new energy grid connection, and power plant step-up applications. It is used for voltage conversion and efficient power distribution, with a maximum capacity of 200MVA. It has been operating reliably in more than 50 countries and regions worldwide. With 30 years of professional manufacturing experience, Hengfengyou Electric provides a complete 66kV transformer selection solution that meets global mainstream standards, high efficiency, long service life, and strong environmental adaptability.

1. Structure Type & Cooling Mode

• Mainstream Type: Three-phase two-winding / three-winding oil-immersed power transformer
• Capacity Range: 20MVA – 200MVA
• Cooling: ONAN, ONAF, OFAF, ODAF available
• Applications: Grid substations, industrial plants, new energy stations, urban substations, power plant 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%, compliant with EU 2015/2014/548/EC Ecodesign Tier 2
• Loss: Low no-load and load loss for long-term energy saving

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

• Two-Winding Transformer
• Three-Winding Transformer

4. Technical sheet for 66kv Power transformer

66kV level,S(F)10,S(F)11-series three-phase double-winding non-excitation regulator power transformer main technical parameters

66kV level,S(F)Z10,S(F)Z11-series three-phase load tap oil-immersed power transformer main technical parameters

5. On-Load Tap Changer (OLTC) Selection

• MR (Germany): High reliability, mechanical life >100,000 operations, for high-end projects
• ABB: Balanced performance, global service network, compatible with intelligent control
• Huaming (China): Cost-effective, fast after-sales service, life ≈50,000 operations
• Principle: Imported brands for harsh environments; domestic brands for cost-sensitive projects

6. Environmental Adaptability

• Enhanced insulation and corrosion protection for high altitude, heavy pollution, salt fog, high temperature
• Low noise, fireproof, enhanced heat dissipation for indoor/underground/urban substations
• Adapted to fluctuating loads of PV and wind power plants

II. 66kV Transformer Design & Installation Scheme

1. Layout & Connection

• Preferred GIS/HGIS switchgear for compact layout and high reliability
• Connected by gas-oil bushing, GIB or power cable
• Complies with N-1 security criterion, supports single/parallel operation

2. Key Installation Procedures

1. Lifting & Placement: Accurate hoisting with qualified crane
2. Accessory Installation: Radiator, bushing, conservator, cooling system, OLTC
3. Vacuum Oil Filling & Hot Oil Circulation: Remove moisture and gas
4. Standing & Venting: Stand ≥24 hours, repeated degassing
5. Grounding: Neutral point, tank, arrester combined grounding; resistance ≤4Ω

3. Protection Configuration

• Zinc oxide lightning arrester on HV side
• CSP HV fuse / circuit breaker
• Complete relay protection: differential, Buchholz, overcurrent, zero sequence, temperature, pressure

III. 66kV 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
• Insulation oil test: breakdown voltage, moisture, DGA
• No-load and load loss test to verify efficiency

2. System Commissioning

• Protection testing: differential and backup protection integrated test
• 5 times no-load impulse closing
• On-load test to verify protection polarity
• Cooling and OLTC linkage test

3. Intelligent O&M & Long Life Design

• Design life >30 years, actual life up to 50 years with proper maintenance
• Optional online monitoring: DGA, core grounding current, winding temperature, partial discharge
• Remote monitoring, condition-based maintenance, intelligent alarm
• Life extension: control winding hot-spot temperature ≤65℃, avoid long-term overload, regular DGA

4. Environmental Protection & Low Carbon

• FR3 vegetable oil available, biodegradability >95%
• Recyclable materials, low carbon footprint, in line with “dual carbon” goals

5. Delivery Time

• Standard model: 90 days
• Emergency order: 50 days fastest
• Custom model: 4–6 months

IV. Core Specification Summary

V. Summary

Hengfengyou 66kV power transformer features 30 years of manufacturing experience, global certifications, efficiency over 99%, service life over 30 years, and fast delivery. It is widely used in state grids, industrial and mining enterprises, new energy step-up stations, regional substations, and power plants. The products run reliably in more than 50 countries including Tanzania, Zimbabwe, Ghana, South Africa, Kenya, Zambia, Sudan, Libya, Congo, UAE, Saudi Arabia, Iraq, Syria, Bangladesh, etc.

We adhere to standardized design, modular manufacturing, intelligent O&M, and full life cycle service to provide customers with safe, reliable, energy-saving and environmentally friendly 66kV power transformation solutions.

VI. 66 KV Power Main Transformer FAQ

Q1: What is a 66kV main power transformer?

A: It is the core equipment of high-voltage grids, used to step down 66kV to 10kV/35kV or step up low voltage to 66kV. Capacity range: 20MVA–200MVA. Components: core, winding, tank, cooling system, protection devices.

Q2: What are the main applications of 66kV transformers?

• Grid hubs: connecting transmission and distribution networks
• Large industries: steel, chemical, mining
• New energy: PV and wind farm step-up
• Urban substations: reliable power for dense areas
• Power plant step-up stations

Q3: Difference between two-winding and three-winding 66kV transformers?

• Two-winding: 66kV + one low-voltage winding; simple, low cost
• Three-winding: 66kV + two medium/low-voltage windings; multi-voltage supply, higher cost

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

• MR: >100k operations, highest reliability, for high-end projects
• ABB: balanced performance, global service
• Huaming: cost-effective, fast service
• Imported for harsh environments; domestic for cost-sensitive projects

Q5: What is the delivery time for 66kV transformers?

• Standard: 90 days
• Emergency: 50 days fastest
• Custom (high impedance, special cooling): 4–6 months

Q6: What is the design life of 66kV transformers?

• Design life: >30 years (IEC standard)
• Actual life: up to 50 years
• Key factors: load rate, maintenance, environment; control winding temp ≤65℃

Q7: What is the warranty term?

• Warranty: 12–36 months after delivery (per contract)
• Coverage: manufacturing defects
• Consumables (OLTC, bushings): usually 1-year separate warranty
• Exclusions: man-made damage, natural disasters, misuse

Q8: What after-sales service is provided?

• Installation guidance, commissioning support, operation training
• Periodic maintenance: oil test, preventive test, condition assessment
• Emergency response: on-site within 72 hours
• Upgrade: intelligent monitoring, capacity expansion, noise reduction

Q9: How to protect against lightning and short circuit?

• Install zinc oxide arresters
• Equip CSP fuses or circuit breakers
• Reliable grounding system (≤4Ω)
• Complete relay protection system