The Principle and Winding Methods of Coil Transformers

Coil transformers are an important device in electrical engineering, widely used in various fields of power transmission and energy conversion. They realize the step-up and step-down of AC voltage and current conversion through the principle of electromagnetic induction. This article will explore in detail the working principle and winding methods of coil transformers, aiming to gain a deeper understanding of their significance in power systems.

Oil-Immersed Power Transformer

Working Principle of Coil Transformers

The basic principle of coil transformers is based on Faraday's law of electromagnetic induction. When alternating current flows through the primary winding of the transformer, it generates an alternating magnetic field around it. This alternating magnetic field passes through the transformer core, forming a closed magnetic circuit, which induces electromotive force in the secondary winding. Specifically, the working principle of the transformer can be broken down into several key steps:

1. Change of Current: When the primary winding is connected to an AC power source, the direction and magnitude of the current change periodically over time.

2. Generation of Magnetic Field: The alternating current in the primary winding flows through the conductors, creating an alternating magnetic field. This magnetic field acts on the transformer core and the adjacent secondary winding in terms of magnetic flux density.

3. Change of Magnetic Flux: According to Faraday's law, any change in the magnetic field will induce electromotive force in adjacent conductors. The change in magnetic flux where the secondary winding is located will result in the generation of induced electromotive force in that winding.

4. Voltage Transformation: The voltage transformation of the transformer is based on its turns ratio. The formula Vp/Vs = Np/Ns illustrates the relationship between the primary voltage Vp and the secondary voltage Vs, where Np and Ns are the number of turns in the primary and secondary windings, respectively. This means that by adjusting the number of turns, different voltage outputs can be achieved to meet the needs of the power system.

Dry-Type Distribution Transformer

Winding Methods

The performance and efficiency of coil transformers largely depend on the quality and method of winding. The rigor of the winding process directly affects the electrical characteristics and mechanical stability of the transformer. Below are commonly used winding methods and considerations:

1. Selection of Materials: First, it is crucial to choose appropriate winding materials. Copper wire with high conductivity is typically used due to its excellent electrical performance and corrosion resistance. In certain high-frequency applications, aluminum wire may also be used as an alternative.

2. Winding Methods:

   - Single-layer winding: This can reduce leakage magnetic losses, but its current-carrying capacity is relatively limited.

   - Multi-layer winding: In transformer manufacturing, multi-layer winding can effectively enhance the coil's current-carrying capacity. However, this method requires ensuring good insulation between layers to avoid short circuits and electric shocks.

   - Dual winding design: For some special transformers, a dual winding structure can be designed, where the primary and secondary windings are independent of each other, reducing mutual inductance effects.

3. Insulation Treatment: After winding, the coils should undergo insulation treatment to ensure good insulation performance between the windings and between the windings and the core. Common insulation materials include phenolic paper and polyester film, which should be selected based on the transformer’s operating environment.

4. Control of Turns and Spacing: During the winding process, the selection of turns must be reasonably calculated according to the design requirements of the transformer. At the same time, ensuring uniform spacing between turns can guarantee the operational performance of the transformer and improve its efficiency.

5. Testing and Adjustment: After winding is completed, the transformer should undergo preliminary testing to ensure there are no short circuits or poor spacing between coils. Data such as voltage ratio and losses should be obtained through testing, and adjustments should be made as necessary to ensure it meets design standards.

As an essential component of power systems, coil transformers operate based on electromagnetic induction and achieve voltage transformation through the turns ratio of the primary and secondary windings. High-quality winding methods are fundamental to ensuring the efficient operation of transformers. With the development of modern power technology, the design, manufacturing, and application of transformers are increasingly moving towards intelligent and efficient directions, highlighting the importance of in-depth research into their principles and technologies.