Working principle and maintenance of synchronous generator (electric ball)

Generator setGenerally, a synchronous generator (also commonly known as an electric ball) is used to convert the rotating mechanical energy of the diesel engine into electrical energy. Various electrical equipment depends on the power generated by it to work, so the working performance requirements of the synchronous generator are very high.

How does a synchronous generator work?

Synchronous generators are manufactured based on the principle of electromagnetic induction. Modern alternators are usually composed of two parts of coils; in order to increase the strength of the magnetic field, part of the coil is wound in a groove on the inner wall of a cylinder made of metal sheets with good magnetic conductivity. This cylinder is fixed on the base and is called stator. The coil in the stator can output induced electromotive force and induced current, so it is also called an armature. The other part of the coil of the generator is wound in the groove of a cylinder made of metal sheets with strong magnetic permeability in the stator cylinder, which is called the rotor. A shaft passes through the center of the rotor and is fastened together. The two ends of the shaft and the machine base form bearing supports. There is a small and uniform gap between the rotor and the inner wall of the stator and it can rotate flexibly. This is called a brushless synchronous generator with a rotating magnetic field structure.

During operation, the rotor coil is supplied with direct current to form a DC constant magnetic field. Driven by the diesel engine, the rotor rotates rapidly, and the constant magnetic field also rotates accordingly. The coil of the stator is cut by the magnetic field lines to generate an induced electromotive force, and the generator emits electricity.

When the rotor and its constant magnetic field are driven by the diesel engine to rotate rapidly, a rotating magnetic field is formed in the small and uniform gap between the rotor and the stator, which is called the rotor magnetic field or the main magnetic field. During normal operation, the stator coil or armature of the generator is connected to a load. The induced electromotive force generated after the stator coil is cut by the magnetic field lines forms an induced current through the load. This current flowing through the stator coil will also generate a magnetic field in the gap, which is called Stator magnetic field or armature magnetic field. In this way, the rotor magnetic field and the stator magnetic field appear in the small and uniform gap between the rotor and the stator. The two magnetic fields interact to form a synthetic magnetic field. The generator generates electricity by cutting the stator coil with the magnetic lines of synthetic magnetic field. Since the stator magnetic field is caused by the rotor magnetic field, and they always maintain a synchronous relationship of one after the other and at the same speed, this generator is called a synchronous generator. Synchronous generators have many advantages in both mechanical structure and electrical performance.

Synchronous generator is a key part of diesel generator set. It is very necessary to establish a suitable working environment for the diesel generator set and perform routine maintenance. How to carry out synchronous generator maintenance in daily power generation equipment operation? As a professional manufacturer of diesel generator sets, Haixing Power has made a basic summary. The following points should be done in the maintenance of synchronous generators.

High temperature, humidity and air pollutants in the generator room are common factors that cause generator failure. The accumulation of dust, dust and other air pollutants will cause the performance of the insulation layer to deteriorate. Not only will it easily form a conductive path to the ground, but it will also increase the friction of the rotor bearing part and generate heat. Moisture and moisture in air pollutants can easily form a leakage path to the ground in the generator, causing generator failure. Excessive temperature in the machine room will make it difficult for the heat generated by the generator set to dissipate, causing its output power to decrease and the unit to overheat. Therefore, sufficient attention should be paid to dust prevention, moisture prevention, ventilation and cooling of the computer room.

Whether it is a single-bearing generator or a double-bearing generator, the coaxiality of the connection between their rotor shaft and the main shaft of the diesel engine is very demanding. After long-term operation, the coaxiality of the unit may sometimes decrease, resulting in an increase in generator noise and excessive temperature. Regular inspection and maintenance should be carried out to maintain good coaxiality.

If the load exceeds the rated load range of the generator, or the three-phase load is very unbalanced, it will also cause the generator to reduce efficiency and overheat.