Transformer and autotransformer type of circuit. What is an autotransformer? Wonder what “autotransformer” is in other dictionaries

There are situations in which it is necessary to change the voltage within very small boundaries. It is easiest to use single-winding transformers, also called autotransformers. In this case, since the transformation coefficient does not differ much from unity, the difference between the strings in the first and second windings will be small. Once we combine the windings, we get a diagram of a basic autotransformer. These transformers belong to the group of devices for special purposes.

The main difference between autotransformers and basic transformers lies in the fact that they have a winding of the lowest voltage and an invisible part of the winding of the highest voltage. In other words, the windings of these windings oscillate, both magnetic and galvanic connections. In order to eliminate voltage shifts or decreases, it is necessary to properly turn on the windings of the autotransformer. It is best to use them in these situations when a minor change in voltage is required. This part of the winding that connects the winding can be made of thin wire, which allows you to protect the metal and, obviously, the property.

Operating principle of autotransformers

Also, with the help of an autotransformer, you can significantly save on steel, which is used to prepare a magnet. If you accept the fact that this plot will cost you a lot of money, then the savings will come out right. In other electromagnetic converters, energy transfer occurs through a magnetic field between two windings. In autotransformers it works both through a magnetic field and through a direct electrical connection.

Similar devices have already begun to show themselves, including from the hot side. Autotransformers compete strongly with traditional double-winding transformers. Only then, if its transformation coefficient does not differ greatly from one. Overall, autotransformers differ little from transformers by design. This is because of the core magnetic circuit on which two windings are installed, from which the windings are taken. Most of the parts that are used in autotransformers are also used in double-winding transformers.

AUTOTRANSFORMER

AUTOTRANSFORMER

a special type of transformer that transforms the data (primary) of the alternating current into the base (secondary) behind only one winding, which plays the role of both the primary and secondary windings. A. replacement of primary transformers is recommended in these surges, if the difference between the primary and secondary voltage is very small.

To eliminate the reduced voltage, the primary voltage is supplied to the ends of the winding; This reduces the voltage coming out of each part of the winding, and the entire winding is under constant tension, and the skin winding is under stress as much less as the number of turns in the entire winding. So. sample, taking the tension from parts of the winding turns, remove the voltage from the secondary winding, which is approximately the same as the voltage of the reduced number of turns. To remove the biased voltage, the primary voltage is supplied to a portion of the turns of the winding and then at the ends it comes out biased. Therefore, the winding has a number of outlets to remove voltages of different sizes.

Technical vocabulary dictionary. - M: State transport service. M. M. Vasilyev, O. M. Isaakyan, N. O. Roginsky, Ya. B. Smolyansky, St. A. Sokovich, T. S. Khachaturov. 1941 .

Wonder what “AUTOTRANSFORMER” is in other dictionaries:

Autotransformer... Spelling dictionary

autotransformer- A transformer, two or more windings of which are galvanically connected so that they create a stink in the hot part [GOST 16110 82] [BAT RAT "IES of Russia" STO 17330282.27.010.001 2008] autotransformer Transformer, in which two more... Adviser of technical translation

Divisor Dictionary of Russian synonyms. autotransformer noun, number in synonyms: 2 divisor (2) ... Glossary of synonyms

An electrical transformer with one winding, which contains a number of pins for connection to the alternating jet and vantagement. Tight autotransformers are used to connect electrical circuits that carry close voltage values. Great Encyclopedic Dictionary

- (Auto transformer) a transformer with one winding, the entire winding is connected to the high-voltage band, and only part of the winding is connected to the low-voltage band. A. there is a decrease in voltage, for example. at the hour when the changer jet engines are started. U ... Marine Dictionary - 3.2 autotransformer: A transformer with two or more windings that are galvanically connected so that stinks are generated on the dirty part.

The purpose and principle of autotransformers

In such situations it is necessary to change the voltage within small limits. The easiest way to do this is not with single-winding ones, called autotransformers. If the transformation coefficient varies little from unity, then the difference between the magnitude of the strims in the first and second windings will be small. What will happen if the offending windings are consumed? See the diagram of the autotransformer (Fig. 1).

The autotransformer is classified as a transformer for special purposes. Autotransformers are differentiated from transformers because the low-voltage winding is part of the high-voltage winding, i.e., both of these windings have magnetic and galvanic connections.

As long as the windings of the autotransformer are switched on, voltage increases and decreases can be eliminated.

Small 1 Schemes of single-phase autotransformers: a - step-down, b - step-up.

As soon as the alternating voltage is applied to points A and X, then there is a changing magnetic flow at the core. Each of the inductive winding turns has an EPC of the same size. Obviously, between points a and X is equal to the EPC of one turn, multiplied by the number of turns laid between points a and X.

If you approach the winding at points a and X, which is important, then the second line I2 will pass in part of the winding and itself between points a and X. And along the line a X, the flow is even small depending on the size of the wires, which is indicated by the difference between these lines. c. This allows part of the winding to be cut from a small cut to protect the copper. If we take into account that this plot becomes the largest part of all turns, then the savings in media turn out to be even more impressive.

Thus, autotransformers are completely modified for a slight reduction or shift in voltage, if in the part of the winding that is lead-in for both windings of the autotransformer, alternating wires are installed, which allows for oscillating with a thinner wire and protect color metal. At the same time, there is a change in the amount of steel spent on the magnetic core, which leads to less output from the transformer.

In electromagnetic energy transformers - transformers - the transfer of energy from one winding to the next is influenced by a magnetic field, the energy of which is concentrated in the magnetic circuit. In autotransformers, the transfer of energy occurs both through a magnetic field and through the electrical coupling between the primary and secondary windings.

Transformer and autotransformer

Autotransformers successfully compete with double-winding transformers if their transformation ratio varies little from one to one or more than 1.5 - 2. With a transformation ratio of at least 3 autotransformers ators cannot tell the truth to themselves.

Structurally, autotransformers differ little from transformers. There are two windings on the magnetic core rods. The pins are taken from two windings and the corner points. Most of the parts of the autotransformer are not structurally different from the parts of the transformer.

Laboratory autotransformers (LATRs)

Autotransformers are also used in low-voltage applications as laboratory low voltage voltage regulators (LAVR). In such autotransformers, voltage regulation occurs when the forged contact is moved by the turns of the winding.

Laboratory regulated single-phase autotransformers are made up of a ring-like ferromagnetic magnetic circuit, wound with one ball of isolated copper dart (Fig. 2).

A number of constant windings have been created around this winding, which allows the installation of devices like autotransformers to step down or move up, with a constant constant transformation coefficient. In addition, on the surface of the winding, cleaned with insulation, there is a narrow track along which to move the brush or roller contact to release the secondary voltage, which is smoothly regulated between zero and 250 V.

When the current turns in the LATR are short-circuited, turn short-circuits are not generated, since the currents and the voltage in the total winding of the autotransformer are close one to one and are directly symmetrical.

Laboratory autotransformers are prepared with a nominal tension of 0.5; 1; 2; 5; 7.5 kVA.

Laboratory autotransformer (LATR)

Three-phase autotransformers

Along with single-phase double-winding autotransformers, three-phase double-winding and three-phase triwinding autotransformers are often found.

In three-phase autotransformers, the phases are connected by a mirror with a designated neutral point (Fig. 3). If it is necessary to reduce the voltage, electrical energy is supplied to the pumps A, B, C and output from the pumps a, b, c, and if the voltage is increased - to the back. They are used as a device for reducing voltage when starting heavy motors, as well as for step-by-step voltage regulation on the pressure of electric furnaces.

Small 3. Diagram of a three-phase autotransformer connecting the phases of the winding with a mirror and a displayed neutral point

Three-phase high-voltage triwinding transformers are also used in high-voltage electrical circuits.

Three-phase autotransformers, as a rule, are connected to a zero-voltage point at the highest voltage. Connection in the mirror will ensure a decrease in voltage, which will ensure that the insulation of the autotransformer is insured.

Stagnation of autotransformers will reduce the efficiency of power systems, reduce the efficiency of energy transfer, and lead to an increase in short-circuit currents.

Few autotransformers

With an autotransformer there is a need to insulate both windings to a higher voltage, winding fragments may cause electrical connections.

The main shortcoming of autotransformers is the galvanic connection between the primary and secondary lancets, which does not allow them to be used as power in the range of 6 - 10 kV at a reduced voltage to 0.38 kV, since the voltage is 380 V p to be brought to the point of mastery on which people operate.

In case of accidents, due to the presence of an electrical connection between the windings in the autotransformer, the voltage may be applied to the lower winding. In this case, all parts of the installation that are operated are connected to the high-voltage part, which prevents maintenance due to the possibility of breakdown of the insulation of the power-conducting parts of the connected electrical installation.

Transformers are equipped with a diverse group of equipment, which has internal functions due to their design features. In addition, different types of work will require different voltages. The average values ​​appear. How to get insurance under the hour of obtaining technical permission for connections. For example, household appliances are rated for 220, or even 110 V. And the power supply axis of the industrial type is 380 V. They have their own options, which are lighter and less expensive. First of all, check out the website to know what the difference is between a transformer and an autotransformer.

Should we reduce the voltage?

Transmission of electricity to distant locations requires high voltage levels, otherwise the wastage of transported energy would make the process unprofitable. In order to use electricity for industrial and, more importantly, everyday purposes, the need for it is reduced. Work on this step-by-step system of transformers, as well as their larger mobile analogues - autotransformers.

Regardless of the fact that all this type of clicking changes the output voltage, transformers can be divided into two types. The first ones - moving ones - increase the tension, supporting sufficient continuation of transportation and recovery for industrial purposes. Others - lowering - by chance, reduce stress, allowing you to harness energy for everyday purposes.

What are insults to devices?

Any transformer is a device of a static type that changes the current flow, frequency, and the number of phases. This device includes two or more windings that are wound around one steel core. One of the windings is electrically connected to the alternating jet. Others may be associated with Kintsev's companions. As a result, there is both an electromagnetic and an electrical connection between them. Additionally, the winding of the autotransformer is equipped with three or more pins, so that it can be connected to different pins and, therefore, pick up different voltage values.

The operating principle is based on electromagnetic induction. Simply put, the magnetic flux that changes when passing through the winding creates an electrically destructive force in it.

This type of transformer is ideal for changing voltage over a very small range.

What is the capacity of a transformer for a car?

The difference between a transformer and an autotransformer is the number of windings. More - for transformers, autotransformers, there is only one copy.

The obvious advantages of auto options are revealed when they are parked at voltage levels of 150 kV or more. They are cheaper, and the cost of windings is significantly less. Autotransformers also sacrifice their size to their static counterparts.

Moreover, autotransformers have a higher coefficient of corrosive action. This is how it is possible for the local community to re-create tension. Warehouses are lined with less wasted materials, and, obviously, less weight and greater compactness.

Its advantages and shortcomings

The main design feature of the autotransformer as a transformer lies in the fact that in the autotransformer part of the HV winding is part of the PN winding. In connection with this, the energy from the primary lancet is transferred to the secondary not only through the magnetic connection between these lances, but through the connection between the central electrical connection between these lances. Let's take a look at the robot of a single-phase lower-cut autotransformer (Fig. 3.2 a).

The section of the winding AX is the furnace for the primary and secondary windings. Nekhtuyuchi strum x. x., let's write down the MDS:

I1 w AX + w aX I2 = 0.

By dividing the level by the number of turns of the winding w AX, we can determine the level of the autotransformer strings:

I 1 + I 2 (w aX / w AX) = 0, or I 1 = - I 2 / k A, (3.5)

de k A = w AX / w aX - transformation coefficient of the autotransformer.-

Along the ground part of the turns AX of the winding of the autotransformer there passes strum I12, equal to the sum of the algebra of strums, then.

I 12 = I 1 + I 2. (3.6)

In a lower autotransformer, the second string is larger than the first one, so I2>I1. This shows that in this transformer strum I12 at the lower part of the turns AH there are traditional differences between the secondary and primary strums:

I12 = I2-I1. (3.7)

Since the transformation coefficient of the autotransformer is three times greater than one, then the flows I1 and I2 differ little from each other, and their difference becomes small. This allows you to remove part of the winding of the autotransformer with a smaller overcut.

Let us introduce the concept of the feed-through voltage of the autotransformer, which represents the entire voltage Spp=U2I2 that is transmitted from the primary to the secondary. In addition, the tension between the primary and second limbs is divided by the magnetic field. This tension is called the fact that the size of the transformer voltage lies within the magnitude of this tension. In a transformer, the entire flow pressure is of the same type, and the fragments between the windings of the transformer are free of magnetic connections. But in the autotransformer between the first and second lances, the magnetic coupling is still electrical. Therefore, the internal tension becomes less of a part of the passing pressure, the other part is transmitted between the lancets without the participation of a magnetic field. To confirm this, we lay out the feed-through tension of the autotransformer Spr=I2U2 in the warehouse. The rate for which is expressed by (3.7), which means that I2 = I1+I12. Substituting this expression in the formula for passing tension, we can reject

S np = U2I2 = U 2 (I 1 + I 12) = U 2 I 1 + U 2 I 12 = S e + S open (3.8)

Here S e --U 2 I1- The tension that is transferred from the primary lance of the autotransformer to the secondary electrical connection between these lances.

Thus, the tension in the autotransformer S dis = U 2 I12 becomes deprived of part of the flow path. This makes it possible to manufacture an autotransformer by rotating the magnetoconductor with a smaller overcut, lowering the transformer's tension.

The middle turn of the winding also becomes smaller; Then, the copper loss on the winding of the auto-transformer changes. Magnetic and electrical losses change simultaneously, and the CCD of the autotransformer moves up.

Such a rank, the autotransformer Porivnyano by the transformer of the RINENSTICAL MAHNITISH Perevgi: Menchu ​​with a vitrati active mother (mіd і Elektrochnaya steel), Bilsh of the Time KKD, Men Rosemors I Vartystya. For high-pressure autotransformers, the CCD reaches 99.7%.

The transfer of the autotransformer is determined to be more significant due to the greater tension S E and, therefore, to the lesser part of the flow force.

The tightness S E, which is transmitted from the primary to the secondary lancet to the electrical connection between these lancets, is indicated by the virus

Se = U2I1 = U2I2/kA = S pr /k A , (3.9)

i.e. the magnitude of the tension S e back is proportional to the transformation coefficient of the autotransformer k A .

From the graph shown in Fig. 3.3 it is clear that the stagnation of the autotransformer gives significant advantages equal to those of a double-winding transformer at low values ​​of the transformation coefficient. For example, with k A = all the tension of the autotransformer is transferred to the second lanyard with the help of an additional electrical connection between the lancers (S e / Spr = 1).

The most important is the stagnation of autotransformers with a transformation coefficient k A 2. With a high value of the transformation coefficient, the small parts of the autotransformer that are present are more important:

Veliki strumi k.z. at the taps of a step-down autotransformer: when points a and X are closed (div. Fig. 3.2, a), voltage U1 is supplied only to a small part of the turns Aa, which draw even a small short-circuit support. In this case, autotransformers cannot be protected from the ruinous action of short-circuit currents, then short-circuit currents. must be interconnected by the support of other elements of the electrical installation, which are switched on before the autotransformer lance.

Electrical connection between the HV side and the PN side; This relies on enhanced electrical insulation of all windings.

When the autotransformers fail in circuits to reduce the voltage between the voltage supply wires and the ground, a voltage appears that is higher than the voltage between the wire and the ground on the HV side.

To ensure electrical safety for service personnel, it is not possible to install autotransformers for the supply of PN circuits in the HV circuit.