Transformer Winding Types Explained

The winding structure of a transformer has a profound impact on its performance. This article briefly introduces several common winding types and analyzes their behavior in terms of electrical performance, heat dissipation, and mechanical stability.

Layer Winding

Layer winding arranges conductors axially in parallel layers around the winding frame. It is commonly used in distribution transformers and electrical equipment rated at 10kV and below.

• Simple structure: Controllable number of coil layers, suitable for small to medium power applications.
• Good heat dissipation: Insulation layers and oil ducts between layers facilitate cooling.
• Uniform voltage gradient: Ideal for low inter-turn voltage applications.
• Easy to automate: High process controllability in mass production.

Disc Winding

Disc winding consists of multiple flat winding units (called "discs") stacked vertically. It is widely used in medium to high-voltage, high-capacity transformers, such as 35kV and above.

• High mechanical strength: Insulated spacers support individual discs to withstand short-circuit forces.
• Optimized capacitance distribution: Promotes voltage balance and resonance control.
• Efficient cooling design: Segmented oil ducts enable directional heat dissipation.
• Flexible connections: Supports series-parallel combinations for precise impedance control.

Helical Winding

Helical winding is typically used for low-voltage, high-current applications such as rectifier or furnace transformers. It resembles a spiral staircase and uses either multiple parallel conductors or single rectangular wires.

• Low turn voltage, simple insulation: Suitable for high-current, low-voltage use.
• Tight inter-turn coupling, low leakage reactance: Enhances transient response.
• Even stress distribution at terminals: Slanted end-cut design reduces axial stress concentration.
• Robust structure: Performs reliably under shock loads or frequent switching.

Foil Winding

Foil winding uses copper or aluminum foil alternated with insulation, ideal for dry-type transformers, rectifiers, or low-voltage, high-current devices.

• Low inter-layer voltage: No voltage jumps between turns, simplifying insulation.
• High automation: Well-suited for modern smart manufacturing.
• Uniform current distribution: Single lateral current path avoids uneven loading.
• Even mechanical stress: Minimal deformation under thermal expansion or short-circuit forces.

Interleaved and Sectional Winding

These designs are often used in high-frequency or voltage-critical transformers.

• Interleaved winding:
  • Improves coupling between windings, reduces leakage inductance.
  • Minimizes voltage spikes, enhances insulation safety margin.
• Sectional winding:
  • Allows independent control of turns, conductor size, and insulation for each section.
  • Helps regulate voltage gradient and electric field distribution in high-voltage designs.

Impact of Winding Structures on Transformer Performance

• Thermal performance: Heat stability depends on the winding form, cooling path, and conductor cross-section.
• Short-circuit withstand: Windings must endure forces from multiple times the rated current; compactness and rigidity are key.
• Electromagnetic parameters: Layout affects leakage inductance, coupling, and distributed capacitance.
• Manufacturing and maintenance: More complex structures require higher processing precision and increase maintenance costs.

Each winding structure type offers distinct technical advantages and application scenarios. Engineers must consider factors like power level, voltage class, cooling method, and operating conditions to select the most suitable winding design.

If you have further technical requirements for winding design or custom transformer development, feel free to contact us for professional support and tailored solutions.