Oil-Immersed Transformers: Core Equipment of Power Systems & Technical Analysis

Introduction

Oil-immersed transformers serve as critical components in power transmission and distribution, performing voltage conversion, energy allocation, and system isolation. This article provides an in-depth analysis of oil-immersed transformer working principles, technical advantages .

1. Working Principle of Oil-Immersed Transformers

Oil-immersed transformers utilize mineral oil insulation and cooling systems for efficient energy conversion:

1. Electromagnetic induction: Primary and secondary windings couple via an iron core magnetic circuit to achieve voltage transformation.

2. Insulating oil functions:

   • Dielectric strength up to 30kV/mm (vs. air’s 3kV/mm)

   • Absorbs heat from windings, limiting temperature rise to ≤65K (IEC 60076 standard)

3. Typical structure:

   • Core (cold-rolled silicon steel, loss ≤0.9W/kg)

   • Windings (copper/aluminum conductors)

   • Conservator (with breather for moisture protection)

2. Technical Advantages of Oil-Immersed Transformers

Compared to dry-type transformers, oil-immersed transformers excel in:

Key advantages:

• Ideal for 110kV+ high-voltage grids

• Failure rate <0.3 incidents/unit-year (CIGRE data)

• Compatible with online DGA monitoring systems