RU146074U1 - TRANSFORMER UNIT FOR ELECTRIFICATED AC RAILWAYS - Google Patents

Abstract

A transformer unit for alternating current electrified railways, comprising a three-phase traction transformer having a three-core magnetic circuit, the rods of which are split into two sections, which are connected by ferromagnetic stops in the upper part of the rod, phases of the secondary winding are connected to the rods, which are connected to the load, on top of the phases of the secondary winding phases of the primary winding connected to the mains are wound, characterized in that the sections of the rod in the lower part are connected by ferromagnetic stops, at ohm, the first section of the secondary winding is wound on the first section of the rod, the second section of the secondary winding is wound on the second section, having a greater number of turns than the first section of the secondary winding, the end of the first section of the secondary winding connected to the beginning of the second section of the secondary winding, on the first section of the rod short-circuited turns are planted.

Description

The utility model relates to electrical engineering, in particular to transformer construction, and can find application in transformer units designed for electrified AC railways.

Known transformer unit for electrified railways of alternating current (RU No. 2321154, H02P 13/06, H01F 29/02, publ.: 03/27/2008. Bull. 9) containing a three-phase traction transformer having a three-core magnetic circuit, the primary winding connected to the supply network, and the secondary winding, the phase windings of which are interconnected, two voltage boosting windings, each of which is located on the middle rod of the three-core magnetic circuit and is connected at one end to the corresponding section of the contact network, and at the other end to one of the windings approx phase secondary winding shaft disposed at the extreme trehsterzhnevogo magnetic circuit, wherein each of the windings is provided with a booster device voltage regulation.

The need to use two additional units - voltage control devices for flexible regulation of the number of turns of boost windings determines the disadvantage of the prototype - its insufficiently high reliability.

The transformer unit for electrified AC railways (RU 2465672 C1; H01F 30/12, H02P 13/10, H01F 29/08, H01F 27/24, 10.27.12), selected as a prototype, contains a three-phase traction transformer having a three-rod magnetic core, the rods of which are split into two sections in the upper part of the rod, the sections are connected by ferromagnetic stops, and movable ferromagnetic anchors are located in the inner spaces between the sections of the rods. The phases of the secondary winding, which is electrically connected to the load, are wound on the rods, the phases of the primary winding connected to the mains are wound on top of the phases of the secondary winding. The phases of the secondary winding protrude beyond the lower ends of the phases of the primary winding.

When the voltage of the primary winding changes, the ferromagnetic anchors accordingly change their position in the inner spaces of the rods, while the magnetic coupling between the primary and secondary windings of the three-phase traction transformer changes, and the voltage of the secondary winding remains unchanged. The mechanical movement of the ferromagnetic anchors to compensate for changes in the voltage of the primary winding is associated with the possibility of their seizing in the inner spaces of the rods, which leads to low reliability of the prototype.

The objective of the utility model is to increase the reliability of the transformer unit for AC electrified railways through the use of a magnetic field created by currents induced in short-circuited turns located in sections of the cores of the magnetic circuit.

The technical result is achieved by the fact that in a transformer unit for electrified railways of alternating current containing a three-phase traction transformer having a three-core magnetic circuit, the rods of which are split into two sections, which are connected by ferromagnetic stops in the upper part of the rod, the phases of the secondary winding are connected to the rods, which are connected with a load, on top of the phases of the secondary winding, phases of the primary winding connected to the mains are wound, sections of the rod in the lower part are connected by ferrom foot, while the first section of the secondary winding is wound on the first section of the rod, the second section of the secondary winding is wound on the second section, having a greater number of turns than the first section of the secondary winding, the end of the first section of the secondary winding connected to the beginning of the second section of the secondary winding, short-circuited turns are planted on the first section of the rod.

The claimed transformer unit for electrified railways of alternating current is illustrated by the drawing. The device contains a magnetic circuit, consisting of two yarns 1 and three rods 2, which are split into two sections 3 and 4, having the same cross-sectional area. In the upper part, sections 3 and 4 of the rods 2 are connected by ferromagnetic stops 5, and in the lower part of the rods 2, sections 3 and 4 are connected by ferromagnetic stops 6. The first section 7 of the secondary winding with a small number of turns and short-circuited turns 8 are wound on the first section 3 of the rod 2. A second section 9 of the secondary winding is wound on the second section 4 of the rod 2, having a greater number of turns than the first section 7 of the secondary winding, the end of the first section 7 of the secondary winding is electrically connected to the beginning of the second section 9 of the secondary winding. Over the secondary winding is wound primary winding 10 connected to the mains. The secondary winding, consisting of sections 7 and 9, is connected to the load 11. Interphase connections are not shown in the drawing

The operation of the transformer unit for electrified AC railways is as follows. Short-circuited coils 8 in the first section 3 act demagnetizing the ferromagnetic material of this section 3, thereby increasing its magnetic permeability, which is equivalent to increasing its cross-sectional area. In this regard, when analyzing the operation of the transformer, we believe that the equivalent cross-sectional area of section 3 is larger than the cross-sectional area of section 4.

The primary winding 10 of the transformer is powered. The alternating current flowing through the primary winding 10 creates an alternating magnetic flux passing through the magnetic circuit, namely: along the sections of the rods 3 and 4 and yokes 1, and at a given nominal voltage value on the primary winding 10, the alternating magnetic flux passes through two sections 3 and 4, is redistributed between them and induces electromotive forces in sections 7 and 9 of the secondary winding, which add up and form a voltage across the entire secondary winding.

With increasing voltage on the primary winding 10, an increase in the current flowing through the primary winding 10, therefore, increases the alternating magnetic flux. Then, due to the high magnetic induction in the second section 4, its material goes into a saturation state and the magnetic resistance of the second section 4 increases, and the magnitude of the alternating magnetic flux passing through the second section 4 decreases. In this case, a large part of the alternating magnetic flux branches off into the first portion 3, since it has a larger equivalent cross-sectional area, and therefore its material is unsaturated and the magnetic resistance of the first portion 3 is small compared to the magnetic resistance of the second portion 4. This portion of the alternating magnetic flux interlocks with the turns of the first section 7 of the secondary winding, induces an electromotive force in it, which mainly generates voltage across the entire secondary winding of the transformer. The decrease in the EMF inducted in the secondary winding section 9 compensates for the increase in the secondary winding voltage due to the increase in voltage on the primary winding 10. As a result, the voltage of the secondary winding, consisting of sections 7 and 9, remains at a given level.

When the voltage on the primary winding 10 decreases, the current flowing through the primary winding 10 will decrease, therefore, it will create a smaller alternating magnetic flux passing through the magnetic circuit, consisting of sections 3 and 4 of the rods 2 and the yoke 1. In this case, the section of the magnetic circuit namely, the second section 4 of the rod 2 with the second section 9 of the secondary winding will exit the saturation state, that is, its magnetic resistance will decrease. The alternating magnetic flux passing through the first 3 and second 4 sections of the rod 2 will be redistributed between them, and will induce in the first 7 and second 9 sections of the EMF, which are added up and generate voltage on the secondary winding, and the magnitude of the EMF induced in the second section 9 will increase, which compensates for the effect of reducing the voltage on the primary winding 10 and the voltage of the secondary winding, consisting of sections 7 and 9, will remain at a given level.

Thus, in comparison with the prototype, the inventive transformer unit for electrified railways is characterized by higher reliability due to the replacement of the action of the mechanical movement of ferromagnetic anchors with the demagnetizing effect of the field of currents induced in short-circuited rings 5.

Claims (1)

A transformer unit for alternating current electrified railways, comprising a three-phase traction transformer having a three-core magnetic circuit, the rods of which are split into two sections, which are connected by ferromagnetic stops in the upper part of the rod, phases of the secondary winding are connected to the rods, which are connected to the load, on top of the phases of the secondary winding phases of the primary winding connected to the mains are wound, characterized in that the sections of the rod in the lower part are connected by ferromagnetic stops, at Ohm, the first section of the secondary winding is wound on the first section of the rod, the second section of the secondary winding is wound on the second section, having a greater number of turns than the first section of the secondary winding, the end of the first section of the secondary winding connected to the beginning of the second section of the secondary winding, on the first section of the rod short-circuited turns are planted.