RU2482564C2 - Three-phase transformer - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: strongly elongated vertical shape enables the transformer placement inside or next to a transmission line pole. The three-phase transformer consists of a pot three-phase magnetic conductor with a central core and heelpieces having an internal and an external part, enclosing the central core and connected to the through insulator on the tank cover. The magnetic conductor and the windings are placed inside the tank filled with a cooling liquid, tightly closed with the cover. The external heelpiece is designed in the shape of a hollow cylinder. The internal heelpiece is shaped as discs with holes for passage of the windings conductors to the through insulators and for the cooling liquid circulation. The top and the bottom covers represent parts of the magnetic conductor. Installed thereon are the through insulators of high and low voltage respectively. The covers, the internal and the external heelpieces and the central core are articulated with minimum gaps and constitute the transformer shorted magnetic conductor.

EFFECT: reduction of the transformer vertical projection overall dimensions.

1 dwg

Description

The invention relates to electrical transformers, and more particularly to a three-phase power oil transformers intended for use in mobile transformer substations.

In land reclamation, mobile electric pumps with transformers are widely used, which make it possible to connect electrical equipment to networks with voltages above 1000 V. Choosing the location of the transformer and switching devices is a problem if there is no free space near the transmission line support. The way out would be a transformer located inside the transmission line support (metal or reinforced concrete special construction). However, typical designs of transformers have dimensions that do not allow them to be placed inside the power transmission towers.

Known transformer according to patent RU 2144229 C1, H01F 30/12, Three-phase symmetrical transformer (published on January 10, 2000), in which the magnetic system contains three identical magnetic cores with a rectangular window, which can be placed one above the other to change the proportions of the transformer.

Known patent RU 2407089 C2, H01F 27/06, H01F 27/26, Clamping, sealing, lifting system for electric transformers and reactors, where the transformer structurally combines parts for different purposes:

the pulling core beam is provided with transport holes for crane hooks.

Closest to the claimed device is an armored three-phase transformer (Kopylov I.P. Electric machines: Textbook for high schools. - M .: Higher school; Logos; 2000, - p.163).

The active part of the transformer contains a core with yokes that close the phase windings that surround the core, while the phase windings are located one above the other, so that the transformer is elongated in the vertical direction with a small projection on a horizontal plane. The core yokes have internal and external parts. The active part of the transformer is placed in a tank with coolant (transformer oil, sovtol, etc.). The tank is hermetically sealed with a lid, on which bushings of higher and lower voltage and other structural parts of the transformer are located (expansion tank, voltage switch, etc.).

The disadvantage of this transformer is the increase in the projection size of the transformer on a horizontal plane due to the size of the outer part of the yoke.

The technical result is to reduce the overall dimensions of the horizontal projection of the transformer.

The technical result is achieved by the fact that a three-phase transformer, consisting of an armored three-phase magnetic circuit with a central rod and yokes having internal and external parts, closing phase windings of higher and lower voltage, which cover the central rod and are connected to bushing insulators located on the tank lid, this magnetic core and windings are placed in a tank filled with coolant, hermetically sealed with a lid, has an external yoke combined with the wall of the tank, made in the form hollow cylinder, the internal yokes are in the form of disks with holes for the passage of the winding conductors to the bushing insulators and coolant circulation, the upper and lower covers also form part of the magnetic circuit, they are equipped with bushing insulators of higher and lower voltage, respectively, while the covers, internal and external yokes and the central rod are articulated with minimal gaps and constitute a closed transformer magnetic circuit.

A useful effect is to reduce the horizontal projection and increase the heat transfer of the transformer and is achieved mainly by changing the design of the magnetic circuit and combining its functions with the wall and lids of the tank.

The invention is illustrated in the drawing, a structural diagram of a transformer.

The transformer magnetic core contains a central rod 1, an upper 2 and a lower 3 of the tank cap, two internal yokes 4 separating the phase windings 5 and the external yoke 6 in the form of a hollow cylinder (pipe). All the described parts of the magnetic system are made of thin-rolled electrical steel sheet with an insulating coating: the outer yoke 6 is wound (rolled up) into a multilayer roll, the inner yokes 4 and the central rod 1 are made of flat plates. The gaps in the interface between the parts of the magnetic system are minimal. The joint of the covers 2 and 3 and the outer yoke of the transformer is sealed. The external yoke simultaneously performs the function of the tank wall. The inner yokes 4 have openings 7 for the passage of the conductors of the windings to the bushing insulators 8 and 9 and the circulation of oil. On the top cover 2 are placed bushings of higher voltage 8; on the lower cover 3 posted low-voltage bushings 9. Phase windings 5 of the higher and lower voltage cover the Central rod 1, located one above the other. The windings are connected in a three-phase circuit (star, triangle or zigzag) and are connected to bushing insulators 8 or 9. respectively. Coolant is poured inside the tank (devices for filling and draining the coolant, expansion tank and other structural elements of the transformer are not shown in the diagram).

The closed magnetic circuit of the transformer is formed by a part of the central rod 1, covers 2 and 3, internal yokes 4 and external yoke 6.

The principle of operation of the claimed transformer is as follows. The windings of the higher and lower voltage 5 conductors through the corresponding bushing insulators 8 and 9 are connected to external electrical circuits (through the corresponding switching devices). The primary winding is connected to a power source (mains); electrical receivers are connected to the secondary winding. When applying a three-phase voltage to the primary winding 5 of the transformer, a magnetizing current and a magnetic field in the magnetic circuit occur in it. The phase winding 5 located in the upper part of the transformer creates a magnetic flux, which closes mainly along the upper part of the central rod 1, the upper cover 2, the upper part of the outer yoke 6 and the upper inner yoke 4; the phase winding 5 located in the middle of the transformer creates a magnetic flux that closes along the middle of the central rod 1, the upper and lower yokes 4 of the middle of the outer yoke 6; The phase winding 5 located at the bottom of the transformer creates a magnetic flux that closes along the bottom of the central rod 1, the lower yoke 4, the lower part of the outer yoke 6 and the lower cover 3.

A three-phase magnetic flux induces an electromotive force in the windings 5 proportional to their number of turns. The transformation coefficient is determined by the ratio of the number of turns of the windings of the higher and lower voltage and the connection diagram of the phase windings. When connected to the secondary winding of electrical receivers in the formed circuit, a secondary current arises, which ensures the operation of the electrical receiver and is transformed into the primary winding.

The dimensions of the projection of the transformer on a horizontal plane are determined by the outer diameter of the windings 5, the thickness of the outer yoke 6 and the gap between them. They are reduced by eliminating the dimensions of the outer part of the yoke of the prototype structure. When constructively placing a switchgear of a higher voltage above the transformer, and under it a lower voltage, the design of the transformer substation acquires a vertically elongated shape, which allows placing the substation inside the supports of power transmission lines (special design) or hanging it on a support and avoiding land allocation for its installation.

Claims (1)

A three-phase transformer consisting of an armored three-phase magnetic circuit with a central rod and yokes having internal and external parts, covering the phase windings of higher and lower voltage, which cover the central rod and are connected to the bushing insulators located on the tank cover, the magnetic circuit and the windings are placed in the tank, filled with coolant, hermetically sealed with a lid, characterized in that the external yoke is combined with the tank wall, made in the form of a hollow cylinder, I have internal yokes the shape of disks with holes for the passage of the winding conductors to the bushing insulators and coolant circulation, the upper and lower covers also form part of the magnetic circuit, they are equipped with bushing insulators of higher and lower voltage, respectively, while the covers, inner and outer yokes, and the central rod are articulated with minimal the gaps and make up a closed transformer magnetic circuit.