Faced with the problem of choosing a generator, you will undoubtedly meet such a concept as an asynchronous generator. Not everyone understands its meaning. If we turn to dictionaries for interpretation, then we will find such a definition: an asynchronous generator is an electric machine that operates in generator mode. It is an auxiliary source of electric current of low power and a braking device. The generator rotor is driven by a drive motor. The direction of its rotation coincides with the magnetic field, but occurs at a higher speed. When the rotor slides, which has acquired a negative value, a braking moment appears on the generator shaft, and the machine gives off electricity to the network. For the operation of such a generator, a reactive power generator was required in the network, for which a synchronous machine is suitable.
To choose a generator for the house and provide your home with uninterrupted electricity, you need to get acquainted with its parameters. First of all, it is necessary to take into account the power of the generator and the total load on it, how many devices it will have to provide electricity. These include the most necessary appliances in everyday life: an electric stove, lighting, a kettle, a boiler. All devices do not have to be connected to the network at the same time, the main thing is that the generator power is enough to ensure their operation without emergency shutdowns. When choosing, one should be guided by the following characteristics: asynchronous generator or synchronous, diesel or gasoline, device power and number of phases.
The power of the generator can be calculated as follows: for this it is necessary to value cosφ, which each electrical appliance has, divided by its power indicated in its technical characteristics. You can also calculate the power of the generator.
Generators come in two types: single-phase and three-phase. They are intended for various purposes. If you use a three-phase generator, then it is necessary to ensure a uniform load between the three phases. When using a single-phase generator, this problem does not arise. A gas-powered generator is more convenient to use in the winter, and its uptime is eight hours. In contrast, the diesel generator has large motor resources and is designed for a longer service life.
Before choosing a synchronous or asynchronous generator, you need to decide what the generator is able to provide high-quality work with devices that consume reactive power, and how it can withstand a high inrush current. A synchronous generator is capable of generating both active and reactive power, and it produces electricity more efficiently. Such a generator withstands inrush currents that exceed two to three times the rated currents. At the same time, its price is quite high.
Unlike synchronous, an asynchronous generator is poorly adapted to inrush currents, but is resistant to short circuits, as well as overloads. With an asynchronous generator, the output voltage is less susceptible to non-linear distortion. It is used to power incandescent lamps, stoves, irons, radio equipment, electric heaters, computers and electronic devices. If it is intended to use a generator with reactive loads, then a power margin of two to three times is required. Its cost is lower than that of a synchronous generator.
The positive characteristics of the generator include its low clear factor, which indicates the number of higher harmonics in its output voltage. This value is equal to two percent. Thus, an induction motor-generator is capable of generating only useful energy. The advantages of an asynchronous generator include its lack of parts that are sensitive to external influences, which require replacement and repair. For this reason, the generator is slightly susceptible to wear and is designed for long-term operation.
If you need an induction motor that is functioning in generator mode, then a collector motor with a permanent magnet on the stator is suitable for this purpose. In this case, you do not even need to make any serious alterations. When the motor shaft rotates at a frequency close to the rated value, a constant voltage will be generated. Stepper motors are also suitable as an asynchronous generator , but they will need to be rotated at a low frequency.