Main parts of an induction alternator. Alternator: design and purpose

Synchronous generator - machine (mechanism) alternating currentthat converts a certain type of energy into electricity. Such devices include electrostatic machines, galvanic cells, solar batteries, thermopiles, etc. The use of each type of the listed devices is determined by their technical characteristics.

Application area

Synchronous units are used as sources of alternating current electricity: they are used at powerful heat, hydro and nuclear power plants, at mobile power plants, transport systems (cars, airplanes, diesel locomotives). A synchronous unit is capable of operating autonomously - as a generator, which feeds any load connected to it, or in parallel with the network - other generators are connected to it.

A synchronous unit can turn on devices in places where there is no central power supply to electrical networks. These devices can be used in farms that are located far from settlements.

Description of the device

The device of a synchronous generator is due to the presence of such elements as:

• The rotor, or inductor (movable, rotating), which includes the field winding.
• An anchor, or stator (immovable), into which the winding is included.
• Unit winding.
• Stator coil switch.
• Rectifier.
• Several cables.
• Electrical compounding structure.
• Welding machine.
• Rotor coil.
• Regulated constant current supplier.

The synchronous generator works as generators and motors. It can move from the generator schedule to the engine schedule - it depends on the action of the rotating or braking force of the device. In the generator schedule, mechanical is included in it, and electricity comes out. In the motor graph, electrical energy enters it, and mechanical energy comes out.

The device is connected to an alternating current circuit of various types of nonlinear resistances. Synchronous units are alternating current generators in power plants, while synchronous motors are used when a motor is needed that operates at a constant rotating frequency.

The principle of operation of the unit

The synchronous generator operates on the principle of electromagnetic induction. During idling, the armature (stator) coil is open, therefore the magnetic field of the unit is formed by one rotor winding. When the rotor rotates from the wire motor, it has a constant frequency, the rotor magnetic field moves through the conductors of the stator phase windings and induces repetitive alternating currents - electromotive force (EMF). EMF is sinusoidal, non-sinusoidal, or pulsating.

The excitation winding is intended to create an initial magnetic fieldto induce electrical driving force into the armature coil. If the armature of the synchronous generator is set in motion by rotating at a certain speed, then excited by a source of constant currents, then the excitation flux passes through the conductors of the stator coils, and variable EMF is induced in the phases of the coil.

Three-phase device

A three-phase synchronous generator is a device that has a three-phase alternating current structure, which is of great practical use. A rotating electromagnet is capable of generating a magnetic flux (alternating), which moves through the three phases of the existing stator winding. And the result of this is that a variable EMF of the same frequency occurs in the phases, the phase shift is carried out at an angle equal to one third of the rotation period of the magnetic fields.

A three-phase synchronous generator is equipped so that the armature on its shaft is an electromagnet and is powered by the generator. When the shaft is rotated, for example from a turbine, the generator supplies electrical current, while the rotor winding is powered by the supplied current. From this, the armature becomes an electric magnet and, performing revolutions with the same shaft, delivers a rotating electromagnetic field.

Synchronous three-phase hydro and turbine generators generate most of the electricity. Synchronous units are also used as electric motors in devices with a power exceeding 50 kW. During the operation of the synchronous unit in the motor graph, the rotor itself is connected to a source of constant currents, while the stator is connected to a three-phase cable.

Excitation structures

Any turbo, hydro, diesel generators, synchronous compensators, motors produced at the moment are equipped with the latest semiconductor structures, such as excitation of synchronous generators. These structures use the method of rectifying three-phase alternating currents of exciters of high or industrial frequency or the voltage of the excited unit.

The generator device is such that the excitation structures can provide such unit operation parameters as:

• The first stage of arousal, that is, the initial.
• Idle work.
• Connection to the network by means of precise synchronization or self-synchronization.
• Work in an energy structure with existing loads or overloads.
• The excitation of synchronous devices can be forced according to such criteria as voltage and current, having a given multiplicity.
• Electrical braking of the apparatus.

Generator design

At the moment, many types are produced induction appliances, but the generator device is designed so that they have the same parts:

• An electromagnet or permanent magnet that produces a magnetic field.
• Variable EMF winding.

To obtain the highest magnetic flux, all generators use a special magnetic structure, which consists of two steel cores.

The windings that create the magnetic field are installed in the grooves of one of the cores, and the EMF-induced windings are installed in the grooves of the other. One of the cores - the inner one - interacts with its winding and revolves around a horizontal or vertical rod. Such a rod is called a rotor. An immovable core with a winding is called an armature (stator).

Instrument characteristics

To evaluate the function of synchronous generators, the same characteristics apply as in generators. direct current... Only some conditions are different and supplemented.

The main characteristics of a synchronous generator are:

• Idling is the dependence of the EMF of the device on the excitation currents, at the same time it is an indicator of the magnetization of the magnetic circuits of the machine.
• The external characteristic is the dependence of the device voltage on the load currents. The voltage of the unit changes in different ways depending on the increase in the load for different types of load. The reasons that cause such changes are as follows:

1. The voltage drop across the inductive and active resistance device windings. It increases as the load of the device, that is, its current, increases.
2. Change in EMF of the unit. Occurs depending on the stator response. With active loads, the voltage decrease will be caused by a voltage drop in all windings, because the stator response entails an increase in the generator EMF. With active-capacitive types of load, the effect of magnetization causes an increase in the current voltage value compared to the nominal value.

• The control characteristics of a synchronous generator are the dependence of the field currents on the load currents. During the operation of synchronous units, it is necessary to maintain a constant voltage at their terminals, regardless of the nature and magnitude of the loads. This is not difficult to achieve if the generator EMF is regulated. This can be done by changing the excitation currents automatically depending on changes in loads, that is, with an active-capacitive load, it is necessary to reduce the excitation current to maintain constant voltage, and with active-inductive and active - increase.

The power of a synchronous generator is determined by the following values:

• Corresponding mains voltage.
• Your EMF.
• Measurement angle.

AC device

A synchronous alternator is an electrical machine that converts mechanical rotational energy into electrical energy of alternating currents. Powerful generators of such currents are installed:

• hydrogenerator turbine generator - at power plants;
• aC devices of relatively low power - in autonomous power supply systems (gas turbine power plant, diesel power plant) and in frequency converters (engine-generator).

Currently, many types of such devices are produced, but they all have a common arrangement of the main elements:

• anchor (stator) - fixed;
• rotor rotating around the axis.

In large industrial generators, an electromagnet, which is a rotor, rotates. At the same time, the windings with induced EMF, laid in the stator slots, remain stationary.

In devices such as a low-power synchronous generator, the magnetic field is generated by a rotating permanent magnet.

Types of synchronous units

There are the following types of synchronous generators:

1. Hydro - in it, the rotor has a difference due to the presence of pronounced poles, it is used in the production of electricity, and operates at low speeds.
2. Turbo - differs in the implicit-pole structure of the generator, it is produced from turbines of various types, the speed of revolutions is quite high, reaching about 6000 rpm.
3. Synchronous compensator - this unit supplies reactive power, is used to improve the quality of electricity to stabilize the voltage.
4. Asynchronous dual power unit - a generator device of this type consists in the fact that it connects both rotor and stator windings from a current supplier with different frequencies. An asynchronous work schedule is created. It is also distinguished by the stability of the work schedule and the fact that it converts different phase currents and is used to solve problems with a narrow specialization.
5. Two-pole shock unit - works in a short-circuit diagram, acts for a short time, in milliseconds. Also tests high voltage devices.

Varieties of aggregates

The synchronous generator (motor) is divided into several models, which are designed for a variety of purposes:

• Step (pulse) - used for drives of mechanisms with a start-stop cycle or continuous motion devices with a pulse control signal (counters, tape drives, drives of CNC machines, etc.).
• Gearless - for use in autonomous systems.
• Contactless - used to work as power plants on ships of the sea and river fleet.
• Hysteresis - used for time counters, in inertial electric drives, in automatic control systems;
• Induction motors - for supplying electrical installations.

Separation by rotor type

By the nature of the rotor device, the generator device is divided into:

• Explicit - with protruding or with pronounced poles. These rotors are used in quiet-running generators whose rotation speed does not exceed 1000 rpm.
• An implicit pole is a cylinder-shaped rotor that has no protruding poles. These armatures are two-pole and four-pole.

In the first case, the rotor consists of a cross, on which the pole cores or field windings are fixed. Secondly - high-speed units with a speed of 1500 or 3000. The rotor is made in the form of a cylinder of fairly high quality steel with grooves, in which an excitation winding is installed, consisting of separate windings of various widths.

History

Systems for generating alternating current have been known in simple forms since the discovery of magnetic induction of electric current. Early machines were developed by pioneers such as Michael Faraday and Hippolyte Pixie.

Faraday developed a "rotating triangle", the action of which was multipolar - each active conductor was passed sequentially through an area where the magnetic field was in opposite directions. The first public demonstration of the most powerful "alternator system" took place in 1886. The large two-phase alternator was built by British electrician James Edward Henry Gordon in 1882. Lord Kelvin and Sebastian Ferranti also developed an early alternator that produced frequencies between 100 and 300 hertz. In 1891, Nikola Tesla patented a practical "high frequency" alternator (which operated at a frequency of about 15,000 hertz). After 1891, multi-phase alternators were introduced.

The principle of operation of the generator is based on the action of electromagnetic induction - the appearance of an electric voltage in the stator winding, which is in an alternating magnetic field. It is created with the help of a rotating electromagnet - a rotor when a direct current passes through its winding. AC voltage converted to constant by a semiconductor rectifier.

Car generator

Automotive alternator. The drive belt is removed.

The alternator is used in modern cars to charge the battery pack and to power the automotive electrical system. AC generators do not use a commutator, which gives a great advantage over DC generators: they are simpler, lighter and cheaper. Automotive alternators use a set of rectifiers (diode bridge) to convert alternating current to direct current. For the production of low ripple DC, automotive alternators have a three phase winding and a three phase rectifier.

Modern automotive alternators have a built-in voltage regulator. Previously, only analog voltage regulators were installed. At the moment, the relay regulators switched to digital channel the so-called CAN bus.

Marine Alternators

Marine alternators in yachts with appropriate adaptation to the saltwater environment.

Brushless Alternators

The brushless generator consists of two generators on one shaft. Small brushless generators may look like one unit, but the two parts are easily identifiable on larger generators. Most of the two are the main generator and the smaller is the pathogen. The exciter has stationary field coils and a rotating armature (power of the coils). The main generator uses opposite rotating field configurations and stationary coils. The bridge rectifier (rotating rectifier) \u200b\u200bis mounted on a plate attached to the rotor. No brushes or slip rings are used, which reduces the number of wearing parts.

Induction generator

Unlike other generators, the operation of an induction generator is based not on a rotating magnetic field, but on a pulsating one, in other words, the field changes not as a function of displacement, but as a function of time, which ultimately (EMF guidance) gives the same result.

The design of induction generators assumes the placement of both a constant field and coils for inducing EMF on the stator, while the rotor remains free of windings, but necessarily has a toothed shape, since the entire operation of the generator is based on the tooth harmonics of the rotor.

Generators for small energy

For powers up to 100 kW, single and three-phase generators with permanent magnet excitation are widely used. The use of high-energy permanent magnets of the composition neodymium-iron-boron made it possible to simplify the design and significantly reduce the size and weight of the generators, which is critical for small wind power.

Alternator design

In the most general case, the most commonly used three-phase alternator consists of a salient-pole rotor with one pair of poles (low-power revolving generators) or 2 pairs of them arranged crosswise (the most common generators with capacities up to several hundred kilowatts. Such a design not only allows more rational use material, but also for an industrial frequency of alternating current of 50 Hz gives an operating frequency of rotation of the rotor 1500 rpm, which is in good agreement with the traction speed of diesel engines of this power), as well as a stator with 3 (in the first case) or 6 (in the second) power windings and poles. The voltage from the power windings is that which is supplied to the consumer.

The rotor can be made on permanent magnets only for very low-power generators, in all other cases it has a so-called winding. field winding, that is, it is a direct current electromagnet fed in a rotating rotor through a brush-collector assembly with simple annular contacts that are more resistant to wear than a split lamellar collector of direct current machines.

In any powerful alternator with an excitation winding on the rotor, the question inevitably arises - how much excitation current should be applied to the coil? After all, the output voltage of such a generator depends on this. And this voltage must be maintained within certain limits, for example, 380 Volts, regardless of the current in the consumer circuit, a significant value of which can also significantly reduce the output voltage of the generator. In addition, the phase load can generally be very uneven.

This issue is solved in modern generators, as a rule, by introducing electromagnetic current transformers into the output circuits of the phases of the generator, connected by secondary windings with a triangle or a star, and giving at the output an alternating three-phase voltage with an amplitude of one - tens of volts, strictly proportional and phase-matched with the magnitude of the phase load current generator - the more current consumed at the moment in this phase, the more stress at the output of the corresponding phase of the corresponding current transformer. This is how the stabilizing and autoregulating effect is achieved. All three control phases from the secondary windings of current transformers are then fed to a conventional 3-phase rectifier of 6 semiconductor diodes, and at its output a constant current of the required magnitude is obtained, and supplied to the rotor excitation winding through the brush-collector assembly. The circuit can be supplemented with a rheostat unit for some freedom of regulation of the excitation current.

In outdated or low-power generators, instead of current transformers, a system of powerful rheostats was used, with the isolation of the operating excitation current by changing the voltage drop across the resistor when the current through it changes. These schemes were less accurate and much less economical.

In both cases, there is the problem of the appearance of the initial voltage on the power windings of the generator at the time of the start of its operation - indeed, if there is no excitation yet, then the current in secondary windings current transformers have nowhere to come from. The problem, however, is solved by the fact that the iron of the rotor yoke has some ability to residual magnetization, this residual magnetization is sufficient to excite a voltage of several volts in the power windings, sufficient to self-excite the generator and reach its operating characteristics.

In self-excited generators, an accidental supply of external industrial voltage is a serious hazard. electrical network to the power stator windings. Although this does not lead to any negative consequences for the generator windings themselves, a powerful alternating magnetic field from the external network effectively demagnetizes the stator, as a result of which the generator loses its ability to self-excite. In this case, an initial supply of excitation voltage from some external source, for example, a car battery, is required, sometimes this procedure completely heals the stator, but in some cases the need for external excitation remains forever.

Main alternator

The main generator consists of a rotating magnetic field, as mentioned earlier, and fixed armature (generator windings)

Hybrid cars

see also

Links

• Alternators. Integrated Publishing (TPub.com).
• Wooden Low-RPM Alternator. ForceField, Fort Collins, Colorado, USA.

For those who are unfamiliar with generators, we explain that this is a unit in which another is obtained from one type of energy. Or, more precisely, from mechanical to electrical. Moreover, these devices can generate both direct current and alternating current. Until the middle of the twentieth century, mainly DC generators were used. They were large machines that didn't work very well. The advent of semiconductor diodes on the market has led to the invention of a three-phase alternator. It is the diodes that allow you to rectify the alternating current.

Principle of operation

The operation of a three-phase generator is based on Faraday's law - the law electromagnetic inductionwhich says that electromotive force will necessarily be induced in a rotating rectangular frame that is installed between the two magnets. In this case, a reservation is made that the magnets will create a rotating magnetic field. The direction of rotation of both the frame and the magnetic field must be the same. But the electromotive force will also arise if the frame remains stationary, and a magnet rotates inside it.

To understand how the generator works, take a look at the figure below. This is the simplest scheme of its work.

Magnets with different poles, a frame, a shaft and slip rings are clearly visible here, with the help of which the current is diverted.

Of course, this is just a diagram, although laboratory generators were created that way. In practice, conventional magnets are replaced by electromagnets. The latter are copper windings or inductors. When passes through them electricity, the required magnetic field is formed. Such generators are installed in all cars (this is for example), in order to start them, a battery is installed under the hood, that is, a direct current source. Some generator models are started on the principle of self-excitation or using low-power generators.

Varieties

The classification is based on the principle of operation, therefore, these AC units are divided into two classes:

• Asynchronous. These are the most reliable generators in operation, small in size and weight, simple in design. They do an excellent job with overloads and short circuits. True, it must be borne in mind that this species immediately fails if a large overload acts on it. For example, starting current electrical equipment. Therefore, it is worth considering this fact, for which you will have to purchase a generator with a capacity three or four times greater than the power consumption of the equipment at startup.
• Synchronous. But this type easily copes with short-term loads. Such a generator can withstand overloading every five or six. True, it does not differ in high reliability compared to the asynchronous options, moreover, it is the owner of large dimensions and weight.

Of course, this division is the principle of operation of the unit. But there are other criteria as well.

• Single phase.
• Two-phase.
• Three-phase.
• Multiphase (usually six phases).
• Welding.
• Linear.
• Induction.
• Stationary.
• Portable.

Three-phase generator device

In principle, the arrangement of a three-phase alternator is quite simple. This is a case with two covers on opposite sides. Each of them has holes for ventilation. The covers have niches for bearings in which the shaft rotates. A transmission element is installed on the front end of the shaft. For example, on car generator a pulley is installed with which rotation is transmitted from the internal combustion engine to the generator. At the opposite end of the shaft, electric current is transmitted, because the shaft in this case acts as an electromagnet with one winding.

The transmission is carried out through graphite brushes and slip rings (they are made of copper). The brushes are connected to an electric regulator (in fact, this is an ordinary relay), which regulates the supply of 12 volts with the required deviations. Most importantly, the relay does not increase or decrease the voltage depending on the speed of rotation of the shaft itself.

So if we talk about three-phase alternators, then these are three such single-phase ones. Only a three-phase unit has a winding not on the rotor (shaft), but in the stator. And there are three such windings, which are phase shifted relative to each other. The shaft, as in the first design, acts as an electromagnet, which is powered by direct current through sliding contacts.

The rotation of the shaft creates a magnetic field in the windings. The electromotive force begins to be induced when the magnetic field of the windings crosses the rotor. And since the windings are symmetrically located on the stator, that is, every 120º, the electromotive force will accordingly have the same amplitude value.

Related entries:

Power generator - one of the constituent elements of an autonomous power plant, as well as many others. In fact, it is the most important element, without which it is impossible to generate electrical energy. An electric generator converts rotational mechanical energy into electrical energy. The principle of its operation is based on the so-called phenomenon of self-induction, when an electromotive force (EMF) arises in a conductor (coil) moving in the lines of force of a magnetic field, which can (for a better understanding of the issue) be called electric voltage (although this is not the same ).

The components of an electric generator are a magnetic system (mainly electromagnets are used) and a system of conductors (coils). The first creates a magnetic field, and the second, rotating in it, converts it into an electric one. In addition, the generator also has a voltage drain system (collector and brushes, connecting the coils in a certain way). It actually connects the generator with consumers of electric current.

You can get electricity yourself, having carried out the simplest experiment. To do this, you need to take two opposite-pole magnets or turn two magnets with different poles towards each other, and place a metal conductor in the form of a frame between them. Connect a small (low-power) light bulb to its ends. If the frame begins to rotate in one direction or the other, the light will start to glow, that is, at the ends of the frame appeared electrical voltage, and an electric current flowed through its spiral. The same thing happens in an electric generator, the only difference is that the electric generator has a more complex system of electromagnets and a much more complex coil of conductors, usually copper.

Electric generators differ in both the type of drive and the type of output voltage. By the type of drive that sets it in motion:

• Turbine generator - driven by a steam turbine or gas turbine engine. Mostly used in large (industrial) power plants.
• Hydro-generator - driven by a hydraulic turbine. It is also used in large power plants operating by the movement of river and sea water.
• Wind generator - driven by wind energy. It is used both in small (private) wind farms and in large industrial ones.
• The diesel generator and the gasoline generator are driven by a diesel and a gasoline engine respectively.

By the type of output electric current:

• DC generators - we get direct current at the output.
• Alternators. There are single-phase and three-phase, with single-phase and three-phase AC output, respectively.

Different types of generators have their own design features and almost incompatible components. They are united only by the general principle of creating an electromagnetic field by mutual rotation of one system of coils relative to another or relative to permanent magnets. Due to these features, only qualified specialists can repair generators or their individual components.

To convert various types of energy into electrical energy, special devices are used. One of the simplest mechanisms is a DC generator, which you can buy at any electrical store or assemble it yourself.

A DC generator is a device that converts mechanical energy into electrical energy for further use in an external circuit. In this case, any mechanical force can serve as a source of mechanical energy: rotation of a special handle, connection of a motor to the device. It should be noted that the overwhelming majority of apartments and houses within the boundaries of any city are supplied with the help of just such generators, only of an industrial type.

Photo - DC generator

An electric current generator can act in exactly the opposite way. Reverse transformation electrical energy into a mechanical one by means of an electric motor. Many motors are equipped with a manual (mechanical) drive, which, if properly connected, can convert energy and networks in the opposite direction.

Principle of operation and device

The DC generator consists of two main parts - the stator and the rotor. Other details:

1. Housing: external generator frame. Often made of cast iron or steel. The housing provides mechanical strength to the entire generator (or motor) structure. It also transmits the magnetic flux generated by the poles;
2. Magnetic poles. They are connected to the body with screws or bolts, a winding is placed on them;
3. The stator, core or yoke is made of ferromagnetic alloys; an excitation coil is installed on this part. The cores are equipped with poles that help determine the direction of flow of charged particles. It is the magnetic tips that generate the magnetic field required for the device to operate;
4. Rotor: generator armature. The core is assembled from individual steel plates to help increase generator efficiency and reduce eddy current generation. When installing the plates, cavities are formed into which the armature winding or self-excitation winding is wound;
5. Switch and brushes. Brushes are made of graphite, and there are at least two of them in the generator. You can find out the number of brushes by counting the poles - this indicator is identical.

Photo - the design of the permanent generator armature

Collector plates are used to connect the terminals of the circuit, they are made from copper, which is known as an excellent conductor of electrical signals.

The principle of operation of a DC generator is based on the formula:

According to him, when a conductor moves in a magnetic field (which makes it possible to reduce magnetic power lines), The EMF of induction is dynamically produced in the conductor. The amount of EMF generated can be specified using the DC generator equation.

One of the main functions of an AC conversion device is to generate an EMF into DC. The direction of the generated EMF will change through each conductor through which energy passes as the rotor rotates. With the help of a switch, a constant flow of charged particles is formed at the generator output. In this case, the output signal looks like this:

Photo - DC generator output signal

Types

There are these types of DC generators: self-excited and working on the principle of independent switching (diagram below). The excitation methods depend on the type of device power supply. A self-excited electric generator works from external sources, it can be a battery or a wind generator. Also, an external excitation system is often implemented on magnets (mainly on devices with low power, up to several tens of watts).

Photo - generator circuit with independent switching

Excitation independent generator produced by power supply from the winding of the device. These devices are also divided into types:

1. Shunt or parallel excitation;
2. Consistent.

The former are distinguished by the parallel connection of the armature winding with the excitation winding, the latter, respectively, by the serial connection of these parts.

Anchor reaction

This is quite common in the idle move generator. It is characterized by the superposition of the resulting magnetic fields by the stator and rotor, which reduces voltage and magnetic field. As a result, the electromotive force of the device falls, there are interruptions in operation, the synchronous generator may even overheat or catch fire due to sparks that appear from improper friction of the brushes.

Photo - generator poles

With this fault, you can do the following:

1. Compensate for the magnetic field with additional poles. This will help to cope with the drop in this characteristic at certain points in the circuit;
2. Repairs are often carried out by simply sliding the collector brushes.

Appointment

Unlike alternators, constant-type devices require an uninterruptible power supply that continually directs DC current into the armature winding. Because of this, the field of application of such devices is rather highly specialized; at the moment they are used in few places.

Photo - the principle of operation of the generator

They are often used to power electric vehicles in cities. Also, DC generators are used to operate an electric car, motorcycle or as ship exciters or welding inverters... They are used as low-speed motors for wind turbines.

The DC diesel generator can be used as an electric motor for powerful industrial machines (traction tractor, harvester, etc.) and a tachogenerator. At the same time, to control the tractor, a powerful unit is required, which specifications are not inferior to indicators of 300 - 400 kW. At the same time, diesel can also replace gas.

Photo - car generator device

The DC generator has the following characteristics (the calculation is performed at n \u003d const):

1. Idling E \u003d f (iв)
2. Formula for sequential excitation U \u003d f (I)
3. Parallel excitation U \u003d f (I)

The study shows that the characteristics can be calculated based on n \u003d 0.

You can find standard indicators in the passport of the device, and they often deviate by several percent (the possible error is also indicated in the instructions for the generator). Self-made generators may have different characteristics from those presented; you can find the necessary data using reference books. You can check them by measuring the available parameters, there is different ways, depending on the type of generator.

DC generator advantages:

1. Unlike a variable-type device, it does not lose energy on hysteresis, as well as on eddy currents;
2. Can work in extreme conditions;
3. Relatively lightweight and lightweight;

This device also has disadvantages. The main thing is the need for an external power source. But sometimes this feature is used as a regulator of an electric machine.

You can buy DC generators in online stores, on import sites, as well as in factories and markets. Sale is also carried out by hand, but we do not recommend using used ones electrical devices... The cost depends on the purpose and power of the device. The price for 4GPEM varies within 30,000 rubles, and for PM-45 - 60,000. When purchasing, a presentation of the work must be made.