In power systems, transformers are a vital device and are widely used in voltage conversion and power transmission. Two-winding transformers and autotransformers are two common types of transformers. They have significant differences in structure, working principle and application scenarios. Understanding the differences between these two transformers is of great practical significance to power engineers and related technicians.

1. Basic structure and working principle

A two-winding transformer, as the name suggests, has two independent windings: a primary winding and a secondary winding. The double windings are coupled to each other through the iron core to form a complete electromagnetic system. When an alternating current passes through the primary winding, the resulting magnetic field induces an electromotive force in the iron core, thereby generating a current in the secondary winding. Because the primary and secondary windings are completely independent, a two-winding transformer is capable of conversion between different voltage levels.

In contrast, an autotransformer has only one winding, and part of the winding serves as both a primary winding and a secondary winding. Its working principle is similar to that of a two-winding transformer, but due to the partial overlap of the windings, the voltage conversion of the autotransformer is achieved by changing the connection method of the windings. This design makes the autotransformer smaller in size and weight under the same power.

2. Efficiency and loss

In terms of efficiency, autotransformers are generally better than two-winding transformers. This is because the overlapping windings of the autotransformer reduce copper and iron losses, thereby improving overall efficiency. Under the same power conditions, the loss of autotransformer is relatively low, which is suitable for applications requiring high efficiency.

However, a two-winding transformer has better electrical isolation due to its independent winding design. This isolation can effectively reduce the risk of fault propagation, especially in high voltage applications where safety is particularly important. Therefore, although a two-winding transformer may be slightly inferior in efficiency, its safety and reliability are indispensable in certain circumstances.

3. Application scenarios

Double-winding transformers are commonly used in substations, distribution networks and industrial equipment in power systems. These occasions have high voltage conversion requirements and electrical isolation needs to be ensured to protect the safety of equipment and personnel. Especially in high-voltage power transmission, the application of double-winding transformers is particularly common.

Autotransformers are mostly used for voltage regulation and power supply, especially in situations where larger power is required. Due to their small size and light weight, autotransformers excel in applications such as motor starting, power conversion, and voltage regulation. Autotransformers are also commonly used in audio equipment and laboratory equipment to meet specific voltage requirements.

4. Cost and economy

In terms of cost, autotransformers are generally more economical. This is because its structure is simple and material consumption is relatively small. In many applications where high efficiency is required, the use of autotransformers can significantly reduce equipment purchase and maintenance costs.

Relatively speaking, the manufacturing cost of double-winding transformers is relatively high, especially when high voltage and power are required. Nonetheless, due to their superior safety performance and electrical isolation characteristics, two-winding transformers are still recommended in many high-risk environments. In this case, the cost of investment is often worth the security it brings.

There are significant differences between double-winding transformers and autotransformers in terms of structure, efficiency, application scenarios and economy. Selecting the appropriate transformer type depends on specific application requirements and safety considerations. In the future development of power systems, as technology advances and application scenarios change, the types and designs of transformers will continue to evolve to adapt to new challenges and needs.

In the work of power engineers, an in-depth understanding of the characteristics of these two transformers will help improve equipment selection and application efficiency, and ensure the stability and safety of the power system.