What current flows through the field winding of a synchronous generator?

Synchronous generator is a common power generation equipment, widely used in power systems, industrial production and scientific research experiments. The excitation winding is an important part of the synchronous generator. Its main function is to provide a magnetic field for the generator to achieve the conversion of electrical energy. This article will introduce in detail the working principle, type, characteristics and precautions of the synchronous generator excitation winding in practical applications.

1. Working principle of synchronous generator

The working principle of synchronous generator is based on the law of electromagnetic induction. When the rotor of the generator rotates in the magnetic field, the coil on the rotor will generate an induced electromotive force, which will generate current in the stator winding. The excitation winding of the synchronous generator is used to generate this magnetic field.

The synchronous generator is mainly composed of two parts: the rotor and the stator. The rotor is equipped with an excitation winding, and the stator is equipped with an armature winding. The excitation winding is usually powered by a DC power supply to generate a DC magnetic field. When the rotor rotates in the magnetic field, the current in the excitation winding interacts with the magnetic field to generate a torque, causing the rotor to continue rotating. At the same time, the magnetic field on the rotor generates an induced electromotive force in the stator winding, thereby generating a current in the stator winding.

2. Types of field windings

The types of excitation windings are mainly divided into two categories: DC excitation and AC excitation.

1. DC excitation

DC excitation is the most common excitation method. The excitation winding is powered by a DC power supply to generate a stable DC magnetic field. The advantages of DC excitation are stable magnetic field and easy control of the output voltage and frequency of the generator. However, DC excitation requires a rectifier to convert AC power into DC power, which increases the complexity of the system.

1. AC excitation

AC excitation is another excitation method. The excitation winding is powered by an AC power supply to generate an AC magnetic field. The advantage of AC excitation is that the system is simple and does not require a rectifier. However, the magnetic field of AC excitation is unstable, and the output voltage and frequency of the generator are difficult to control.

3. Characteristics of the field winding

1. Magnetic field strength

The magnetic field strength of the excitation winding is proportional to the excitation current. The larger the excitation current, the higher the magnetic field strength, and the greater the output voltage and power of the generator. However, excessive excitation current will cause the generator to overheat and affect its normal operation.

1. Magnetic field distribution

The magnetic field distribution of the excitation winding has a great influence on the performance of the generator. The ideal magnetic field distribution should be uniform to reduce the impact of magnetic field inhomogeneity on the performance of the generator. In practical applications, the design of the excitation winding needs to consider the uniformity of the magnetic field distribution.

1. Resistance of the field winding

The resistance of the excitation winding affects the magnitude of the excitation current, and thus the strength of the magnetic field. The smaller the resistance of the excitation winding, the greater the excitation current and the higher the magnetic field strength. However, if the resistance of the excitation winding is too small, the excitation current will be too large, affecting the normal operation of the generator.

4. Matters Needing Attention in Practical Application of Field Winding

1. Control of excitation current

The control of excitation current is the key to ensure the normal operation of the generator. Excessive excitation current will cause the generator to overheat and affect its normal operation. Therefore, in practical applications, it is necessary to reasonably control the excitation current according to the capacity and load of the generator.

1. Heat dissipation of field winding

The excitation winding generates heat during operation and needs to be dissipated. When designing the excitation winding, its heat dissipation performance needs to be considered to ensure the normal operation of the generator.

1. Field winding protection

The excitation winding may be affected by external factors during operation, such as voltage fluctuation, overload, etc. Therefore, in practical applications, the excitation winding needs to be protected to prevent it from being damaged.

1. Maintenance of field winding

The maintenance of the excitation winding is an important part to ensure the normal operation of the generator. In practical applications, it is necessary to regularly check the working status of the excitation winding and replace damaged parts in time to ensure the normal operation of the generator.

V. Conclusion

The excitation winding of a synchronous generator is an important part of the generator, and its performance directly affects the output voltage and power of the generator. In practical applications, it is necessary to reasonably select the excitation method and control the excitation current according to the capacity and load of the generator to ensure the normal operation of the excitation winding. At the same time, the excitation winding needs to be cooled, protected and maintained to extend the service life of the generator.