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Operating Characteristics Of Generators

Oct 12, 2017

The main performance of the generator is no-load characteristics and load operating characteristics. These characteristics are the important basis for users to choose generators.

No-load characteristics:

When the generator is not connected to the load, the armature current is zero, which is called no-load operation. At this time, the three-phase winding of the motor stator is only the E0 (three relative) of the no-load electromotive force produced by the excitation current if sense, Generators and its size increases with the increase of IF. However, because the magnetic circuit core of the motor saturation phenomenon, Generators so the two are not proportional. The curve that reflects the E0 of no-load electromotive force and excitation current is called the no-load characteristic of generator.

Armature reaction:

When the generator is connected with a symmetrical load, the three-phase current in the armature winding produces another rotating magnetic field, called the armature reaction magnetic field. Its rotational speed is exactly the same as that of the rotor, and the two rotate synchronously. The armature reaction magnetic field of the generator and the excitation magnetic field of the rotor can be approximately distributed according to the sine law. Generators The space difference between them depends on the time phase difference between the no-load EMF E0 and the armature current I. The armature reaction magnetic field is also related to the load condition. When the load of the generator is electrical sensibility, the armature reaction magnetic field plays a demagnetization role, Generators which will cause the voltage of the generator to decrease; When the load is capacitive, the armature reaction magnetic field plays a role in helping to increase the output voltage of the generator.

Load Run Characteristics:

Mainly refers to the outward characteristic and the adjustment characteristic. The external characteristic is the relationship between the voltage U and the load current I of the generator when the speed is the nominal value, the excitation current and the load power factor are constant. The adjustment characteristic is the relation between the speed and the end voltage as the rated value and the load power factor is constant, Generators the excitation current if and the load current I. The voltage variation rate of generators is about $number. General industrial and household loads require that the voltage remain basically unchanged. Therefore, as the load current increases, the excitation current must be adjusted accordingly. Generators Although the change trend of the adjustment characteristic is opposite to the outward characteristic, for the perceptual and the pure resistive load, it is ascending, Generators but under the capacitive load, the general is descending.

Operating Characteristics of generators:

The operation characteristics of the generator are five kinds, such as no-load characteristic, short-circuit characteristic, load characteristic, outer characteristic and adjustment characteristic.

External characteristics and adjustment characteristics are the main operating characteristics, according to these characteristics, Generators can determine whether the operation of the generator is normal, in order to adjust in time to ensure high-quality and safe power generation. No-load characteristics, short-circuit characteristics and load characteristics are the characteristics of testing the basic performance of generators for measuring and calculating the basic parameters of generators.

The generator is mainly composed of rotor (magnetic pole), stator (armature), rectifier, voltage regulator, front and rear end cover, brush and brush frame, and the function of each part is presented below.

1, the function of rotor rotor is to produce magnetic field. The rotor is composed of claw pole, magnetic choke, excitation winding, slip ring and rotor shaft.

2, stator stator installed in the outside of the rotor, and the front and rear end of the generator fixed together, when the rotor in its internal rotation, caused by the stator winding flux change, the stator winding in the induction electromotive force.

3. The function of rectifier rectifier is to convert three-phase alternating current of stator windings into direct current. The rectifier consists of a rectifier plate and a rectifier diode.

4. The voltage regulator regulates the output voltage of the alternator.

5, end cover and brush assembly end cover is divided into front cover and back end cover to support the rotor, stator, rectifier and brush assembly function. An electric brush assembly is arranged on the back end cover. The brush assembly consists of an electric brush, Generators an electric brush holder and an electric brush spring. The effect of the brush is to introduce the power supply through the sliding ring into the excitation windings. The two brushes are mounted in the hole of the brush holder, and the spring pressure is used to keep in touch with the slip ring.