Oil-Immersed Transformers Winding Technology White Paper

This white paper provides a comprehensive technical analysis of winding systems for oil-immersed transformers, covering material selection, manufacturing processes, performance optimization, and emerging technologies. The document serves as a technical reference for engineers, procurement specialists, and maintenance professionals in the power transmission and distribution industry.

I. Scientific Material Selection Guide

1. Conductor Material Performance Matrix

• Cost-benefit analysis: Electrolytic copper (99.95% purity) vs oxygen-free copper (99.99%)
• Advantages of copper foil windings (0.05-0.2mm) in high-frequency oil-immersed transformers
• Feasibility study of aluminum windings for cost-effective oil-immersed transformers

2. Insulation System Specifications

• Selection criteria for oil-resistant insulation paper (0.08-0.13mm)
• Temperature performance of eco-friendly insulating varnish (130-180℃)
• Evaluation of novel composite insulation materials (Nomex+polyimide)

II. Manufacturing Processes

1. Precision Winding Technology

• CNC winding machine accuracy control (±0.05mm)
• Impact of interlayer insulation on partial discharge
• Vacuum Pressure Impregnation (VPI) process optimization

2. Quality Control System

• Critical Control Points (CCP) in production
• Online detection technologies (X-ray, ultrasonic)
• Finished product testing standards (IEC 60076)

III. Failure Analysis

1. Common Failure Modes

• Winding deformation detection methods
• Characteristic gas analysis for insulation aging (CO/CO₂ ratio)
• Correlation between PD signals and defects

2. Preventive Maintenance

• Condition assessment indicators
• Early warning systems using DGA
• Infrared thermography for hotspot detection

IV. Innovative Winding Technologies

1. Smart Winding Systems

• Distributed temperature monitoring with optical fibers
• Lifecycle management using embedded RFID
• Self-diagnosing intelligent windings

2. Eco-Friendly Solutions

• Recyclable winding materials
• Solvent-free insulating varnish research
• Bio-based insulation material development

V. Standardization Framework

1. International Standards Comparison

• IEC 60076 vs GB 1094 requirements
• IEEE C57.12.00 mechanical strength provisions
• EN 50588 industrial transformer specifications

2. Certification Processes

• Type test requirements
• Third-party certification focus (e.g., KEMA)
• UL certification essentials

VI. Application Case Studies

1. Renewable Energy Applications

• Special designs for PV plants
• Corrosion protection for offshore wind
• High-frequency winding optimization for energy storage

2. Industrial Special Cases

• Impact-resistant designs for steel mills
• Explosion-proof solutions for mining
• Chemical-resistant winding systems

VII. Technical Q&A

Q1: When to replace windings?
A1: Consider replacement when: ① DC resistance variation >2% ② Insulation resistance drop >50% ③ FRA deviation >3dB

Q2: Temperature limits at different loads?
A2: Refer to IEC 60076-7: Continuous operation <95℃ (hotspot), Short-term overload <140℃ (maximum)

Q3: Repair vs replacement economics?
A3: Replacement recommended when: Repair costs >60% of new winding or lifespan reduction >30%

VIII. Technology Outlook

1. Material Innovations

• 2D material-enhanced conductors
• Self-healing insulation materials
• Superconducting winding breakthroughs

2. Digital Twin Applications

• Winding modeling methodologies
• Big data-based remaining life prediction
• VR applications for maintenance training

This white paper is prepared by the Winding Technology Center of Power Equipment Research Institute, with data current to Q3 2023. For detailed technical consultation on oil-immersed transformer windings, please contact our engineering specialists.