1.Types and functional characteristics of generator
A generator is a device that generates electricity when subjected to mechanical power. In this conversion process, mechanical power comes from a variety of other forms of energy, such as wind energy, water energy, heat energy, solar energy and so on. According to different types of electricity, generators are mainly divided into DC generators and AC generators.
1. Functional characteristics of DC generator
DC generator has the characteristics of convenient use and reliable operation. It can directly provide electric energy for all kinds of electrical equipment requiring DC power supply. However, there is a commutator inside the DC generator, which is easy to produce electric spark and low power generation efficiency. DC generator can generally be used as DC power supply for DC motor, electrolysis, electroplating, charging and excitation of alternator.
2. Functional characteristics of alternator
AC generator refers to the generator that generates AC under the action of external mechanical force. This kind of generator can be divided into synchronous AC power generation
Synchronous generator is the most common among AC generators. This kind of generator is excited by DC current, which can provide both active power and reactive power. It can be used to supply power to various load equipment requiring AC power supply. In addition, according to the different prime movers used, synchronous generators can be divided into steam turbine generators, hydro generators, diesel generators and wind turbines.
Alternators are widely used, for example, generators are used for power supply in various power stations, enterprises, shops, household standby power supply, automobiles, etc.
Model and technical parameters of generator
In order to facilitate the production management and use of the generator, the state has unified the compilation method of the generator model, and pasted the generator nameplate at the obvious position of its shell, which mainly includes the generator model, rated voltage, rated power supply, rated power, insulation grade, frequency, power factor and speed.
Model and meaning of generator
The model of the generator is usually a description of the model of the unit, including the type of voltage output by the generator, the type of generator unit, control characteristics, design serial number and environmental characteristics.
In addition, the models of some generators are intuitive and simple, which is more convenient to identify, as shown in Figure 6, including product number, rated voltage and rated current.
(1) Rated voltage
Rated voltage refers to the rated voltage output by the generator during normal operation, and the unit is kV.
(2) Rated current
Rated current refers to the maximum working current of the generator under normal and continuous operation, in Ka. When other parameters of the generator are rated, the generator operates at this current, and the temperature rise of its stator winding will not exceed the allowable range.
(3) Rotational speed
The speed of the generator refers to the maximum rotation speed of the main shaft of the generator within 1min. This parameter is one of the important parameters to judge the performance of generator.
(4) Frequency
Frequency refers to the reciprocal of the period of AC sine wave in the generator, and its unit is Hertz (Hz). For example, if the frequency of a generator is 50Hz, it indicates that the direction of its alternating current and other parameters 1s change 50 times.
(5) Power factor
The generator generates electricity by electromagnetic conversion, and its output power can be divided into two types: reactive power and active power. Reactive power is mainly used to generate magnetic field and convert electricity and magnetism; The active power is provided for users. In the total power output of the generator, the proportion of active power is the power factor.
(6) Stator connection
The stator connection of generator can be divided into two types, namely triangular (△ shaped) connection and star (Y-shaped) connection, as shown in Figure 9. In the generator, the three windings of the generator stator are usually connected into a star.
(7) Insulation class
The insulation grade of generator mainly refers to the high temperature resistance grade of its insulation material. In the generator, the insulating material is a weak link. The material is easy to accelerate aging and even damage at too high temperature, so the heat resistance grade of different insulating materials is also different. This parameter is usually represented by letters, where y indicates that the heat-resistant temperature is 90 ℃, a indicates that the heat-resistant temperature is 105 ℃, e indicates that the heat-resistant temperature is 120 ℃, B indicates that the heat-resistant temperature is 130 ℃, f indicates that the heat-resistant temperature is 155 ℃, H indicates that the heat-resistant temperature is 180 ℃, and C indicates that the heat-resistant temperature is more than 180 ℃.
(8) Other
In the generator, in addition to the above technical parameters, there are also parameters such as the number of phases of the generator, the total weight of the unit and the manufacturing date. These parameters are intuitive and easy to understand when reading, and are mainly for users to refer to when using or purchasing.
3、 Symbol identification of generator in line
Generator is one of the essential components in control circuits such as electric drive and machine tool. When drawing the schematic diagram corresponding to each control circuit, the generator is not reflected by its actual shape, but marked by drawings or diagrams, letters and other symbols representing its function.
Post time: Nov-15-2021
