Technical White Paper on Oil-Immersed Transformers: Complete Guide to Selection, Application and Maintenance

Chapter 1: Technical Essentials of Oil-Immersed Transformers

As core equipment in power systems, oil-immersed transformers determine the operational efficiency and stability of entire power grids. Modern oil-immersed transformers incorporate multiple technical optimizations:

1. Magnetic Circuit System:
   • High-quality cold-rolled silicon steel sheets reduce no-load loss by over 40%
   • Step-lap core construction lowers noise below 55dB
   • Amorphous alloy transformers achieve only 20-30% no-load loss of conventional units
2. Winding Structure:
   • Multi-layer cylindrical windings ensure uniform electric field distribution
   • Transposed conductor technology reduces additional losses by over 15%
   • Nomex insulation paper withstands temperatures up to 220℃
3. Oil Circuit Design:
   • 3D oil duct design improves heat dissipation efficiency by 30%
   • Corrugated tank expansion coefficient exceeds 100%
   • New antioxidants extend oil service life to 15 years

Chapter 2: In-Depth Interpretation of Model Parameters

2.1 Detailed Explanation of Model Naming System

Example “SFSZ11-50000/110”:

• S: Three-phase
• F: Forced air cooling
• S: Three-winding
• Z: On-load tap changer
• 11: Design series
• 50000: Rated capacity 50MVA
• 110: High-voltage side 110kV

2.2 Key Performance Parameters

• No-load loss: S13 reduces 20-25% compared to S11
• Load loss: Amorphous alloy transformers reduce 60-70%
• Short-circuit impedance: Standard value 4-10%, must match system
• Temperature rise limits: 55K for top oil, 65K for winding

Chapter 3: Intelligent Maintenance Solutions

3.1 Online Monitoring System

1. Dissolved Gas Analysis:
   • H₂ warning value: 150ppm
   • C₂H₂ attention value: 5ppm
   • Three-ratio method for precise fault diagnosis
2. Smart Terminal:
   • Real-time monitoring of 20+ parameters
   • Edge computing for local diagnostics
   • 4G/5G wireless data transmission

3.2 Predictive Maintenance

• AI-based lifespan prediction models
• Remaining life assessment error <5%
• Smart alarm accuracy >90%

Chapter 4: Analysis of Typical Application Scenarios

4.1 Renewable Energy Power Stations

• Technical Challenges:
  • High harmonic content (THD>5%)
  • Severe load fluctuations
  • Difficult maintenance in remote areas
• Solutions:
  • Reinforced winding design
  • Active filter configuration
  • Intelligent monitoring systems

4.2 Urban Power Grids

• Special Requirements:
  • Fire protection class B1
  • Noise limit 55dB daytime
  • Optimized footprint
• Recommended Models:
  • SFZ11 fully sealed transformers
  • Compact substation solutions
  • Special designs for underground substations

Chapter 5: Full Lifecycle Management

5.1 Cost Optimization Model

5.2 Eco-Friendly Disposal Solutions

• Waste oil recycling rate >95%
• Copper recovery purity 99.9%
• 100% silicon steel recyclability
• Certified environmental disposal system

This white paper was prepared by expert teams from the Power Equipment Research Institute. For complete technical documentation or customized solutions, please contact professional transformer technical service providers. Through scientific full lifecycle management, oil-immersed transformers can improve comprehensive benefits by over 30%, providing reliable support for new power system construction.