UA44616C2 - Three-phase switch for switching transformer winding taps under load - Google Patents

Abstract

A three-phase switch for switching transformer winding taps under load contains a casing made of dielectric with bottom and lid, contactor mechanism with commutating and additional contacts, forming contacting groups, resistors installed in the casing, immobile contacts disposed on the casing walls and connected to the transformer and to the phases taps removers, switching mechanism installed in the lid. The mechanisms of the three phase contactors are disposed in the common casing, and their contact groups are displaced phase by phase each along the casing axes by mounting of one or two phases on the dielectric stands. As the stands the resistors are used disposed in the dielectric housings and set under the contact group of the contactor mechanisms, distant from the casing bottom. Between the phase contact groups of the contactor mechanisms the dielectric partitions are installed. The three phase taps removers are installed in the common casing, and their contacts are disposed on the planes distanced one from another at a gap equal to the distance for an insulation between the phases.

Description

The invention relates to electrical engineering and can be used in the construction of three-phase branch switches of windings of power transformers under load.

A well-known device for switching branches (unsoldering) of transformer windings under load according to Japanese patent Meob2-62443, class. NOTE 29/04, 1987 contains a contactor and a desoldering selector.

The contactor and selector have their own housings, located one above the other and designed for single-phase voltage regulation.

The disadvantage of the known design is the need to have three such switching devices to regulate the voltage of three phases, accordingly, material costs and the cost of the transformer are significantly increased.

The known contactor of the switching device for regulating the voltage of the transformer under load according to the author's certificate of the USSR Mo520686, cl. НО2гР13/06, NOTE29/04, 1976. contains switching, auxiliary and arc extinguishing contacts with a resistor.

The disadvantage of the contactor of the known device is the complexity of the design, while the contactor is also designed to regulate the voltage of one phase, and three contactors are needed to regulate three phases, which increases material costs.

The well-known three-phase branch switch (unsoldering) in the transformer winding under load according to the European patent Me0185530, cl. NOTNO/00, 1986 contains contactors and desoldering selectors.

The contactor of each phase contains a housing made of dielectric with a bottom and a cover, in which the contactor mechanism is installed with switching and additional contacts that form a contact group, and resistors.

The contactor mechanism is installed on the bottom of the housing, and on the walls of the housing, fixed contacts are installed for connection with the transformer and selector.

Contactors and selectors of three phases are located in two nodes, while contactors of two phases are axially located in one node, and below them is a selector of one phase, electrically connected to the contactor closest to it.

In another node, the contactor of the third phase and selectors of two phases are located axially.

The lower selector is electrically connected to the upper contactor of the first node, and the upper selector is connected to the contactor located above it.

The kinematic connection of contactors and selectors is provided by the switching mechanism, the elements of which are placed in the covers of the upper contactors and between the contactors and selectors.

This layout of the switch ensures voltage regulation in three-phase systems, reduces the area occupied by the switch in the plan and slightly reduces the consumption of materials.

We take this construction as the closest analogue.

The disadvantages of the closest analogue are increased material consumption and high cost, because for the manufacture of such a three-phase switch, it is practically necessary to manufacture three single-phase contactors and three selectors, then connect them electrically and kinematically into a three-phase system.

The basis of the invention is the task of developing a design of a three-phase branch switch of the transformer windings under load, which provides a simplification of the design, a reduction in material consumption and cost, and an increase in operational reliability.

The solution to the problem is provided by a three-phase transformer winding branch switch under load, which contains a case made of a dielectric with a bottom and a cover, contactor mechanisms with switching and additional contacts forming contact groups, and resistors installed in the case, fixed contacts located on the walls of the case and connected to the transformer and phase branch selectors, the switching mechanism, due to the fact that the three-phase contactor mechanisms are installed in one housing, and their contact groups are phase-shifted relative to each other along the axis of the housing by installing one or two phases on dielectric supports.

To reduce dimensions, resistors located in dielectric housings and installed under contact groups of contactor mechanisms, remote from the bottom of the housing, can be used as stands.

To increase the reliability between the contact groups of the phases of the contactor mechanisms, partitions made of dielectric are installed.

To reduce the number of main nodes, the tap selectors of the three phases are placed in one housing, and their contacts are located in planes separated by phase from each other by a distance corresponding to the interphase insulation distance.

The technical result achieved when using the invention: - reduced consumption of materials, because the mechanisms of the three-phase contactors are made in one general body of the three-phase switch with the switching mechanism installed in the cover; - reduced dimensions of the three-phase switch due to the rational arrangement in plan and height of the contact groups of the contactor mechanisms and the installation of interphase partitions made of dielectric; - the reduced height of the three-phase switch due to the location of the three-phase selectors in one housing in combination with the optimal layout of the three-phase contactor mechanisms; - significantly reduced cost of the switch due to the reduction of the number of main nodes; - increased operational reliability due to simplification of the kinematic connection of nodes and ensured electrical strength of interphase gaps.

The claimed three-phase on-load branch switch of the transformer windings is explained by the following description and drawings, where:

Fig. 1 - a general view of a three-phase switch of branches of transformer windings under load;

Fig. 2 - a sectional view of Fig. 1;

Fig. 3 - the scheme of regulation of one phase of the switch;

Fig. 4 - a version of the configuration of the switch contactor phases;

Fig. 5 - a diagram of the sequence of switching contacts of contactor mechanisms, for example, one phase X.

According to the invention, the three-phase branch switch of the transformer windings contains a contactor 1, located axially above the selectors 2 of the winding branches, a switching mechanism C with a drive 4 and a pre-selector 5 for switching reversal (see Fig. 1).

Contactor 1 has three phases X, MU, 7 contactor mechanisms b, installed in a housing 7 made of dielectric material, with a bottom 8 and a cover 9 (see Fig. 2).

The contactor mechanism 6 has two arms 10, 11 with main (switching) contacts 12, 13 and additional contacts 14, 15, 16, 17.

Contacts 14, 15 are auxiliary, and contacts 16, 17 are arc extinguishing and are connected to the linear inputs хХл, Ул, 7п of the regulating winding (RO) through resistors 18, 19 (see Fig. 3).

The indicated contacts of the contactor mechanisms b form contact groups 20, which are separated in phase relative to each other along the axis of the body 7 due to the installation of one or two contact groups 20 of the contactor mechanisms on the dielectric supports 21 (see Fig. 2).

As supports 21, resistors 18, 19, located in dielectric housings, which are installed in phases above or below the contact groups 20 of the contactor mechanisms (see Fig. 4), can be used.

Fixed contacts 22 for connection to the transformer and contacts 23 for connection to selectors 2 of the phase branches of the transformer windings are installed on the wall of the housing 7 of the contactor 1 (see Fig. 1).

Partitions 24 made of dielectric are installed between the contactor mechanisms of 6 phases (see Fig. 2, Fig. 4).

Selectors 2 of three phases are placed in one case 25 of dielectric with fixed contacts 26, which are connected to the branches of the winding (PO) of the transformer (see Fig. 2).

Fixed contacts of 26 selectors of 2 phases X, M, 2 divided into two rows, even contacts -X2,4,6,8,10,42,4,6, 8,10,272,4,6, 8,10 and odd contacts- X1,3,5,7,9,1,3,5,7,9,21, 3, 5, 7, 9.

Paired contacts in each phase are offset relative to odd ones by the height of the case 25. Contacts of phases X, M, 7 are installed in planes separated from each other along the axis of the case by a distance corresponding to the interphase insulation distance.

Along the axis of the housing 25, a bakelite shaft 27 with current-collecting rings 28 connected to the corresponding arms 10, 11 of the contactor 1 is installed. The movable contacts 29 of the lamella type are installed on coaxial bakelite shafts 30, 31 (see Fig. 2).

The preselector 5 has a shaft 32 with movable contacts 33 fixed on it and a sector 34 with fixed contacts X 11, 13, M 11, 13, 7 11, 13.

The kinematic connection of the selector 2 and the preselector 5 with the switching mechanism 3 of the contactor 1 is carried out using a shaft 35 and Maltese gears 36 (see Fig. 2).

For the switch to work, it is necessary to switch the contacts of selector 2 and flip the contacts of contactor 1.

The sequence of operation of the contactor is explained in Fig. 5.

Position "a" corresponds to the working position of the switch, contacts 13, 15, 17 are closed, and contacts 12, 14, 16 are open.

Position "b" shows the beginning of switching: the main contacts 12 and 13 are open, and the additional contacts 15 and 17 are closed.

All current passes through auxiliary contacts 15.

In the "in" position, the contacts 15 open, and the current passes through the resistor 19 and the arc extinguishing contacts 17.

The "r" position shows the "bridge" moment, that is, the moment when both arc extinguishing contacts 16 and 17 are closed, which leads to the closing of the winding stages (RO) through resistors 18 and 19.

The magnitude of the circulating current in this stage of the winding (PO) is determined by the value of the resistances of resistors 18 and 19, connected in series in the circuit of the closed stage of the winding (PO).

With further movement of the contacts of the contactor mechanisms in the "d" position, the arc extinguishing contacts 17 of the arm 10 open, and the contacts 16 of the arm 11 remain closed.

When the contacts are next moved to the "e" and "h" positions, the auxiliary contacts 14 and the main contacts 12 of the arm 11 are closed sequentially.

The "w" position corresponds to the working position of the switch on the switched branch of the winding (RO) of the transformer.

In the position of Fig. 3, the main winding of phase X of the transformer is connected to the regulating winding (RO) through the contacts X10 and X11 of the preselector 5, and the regulating one - through the contact X6 of the selector 2 and the contacts of the contactor 1 are connected to the linear contact Xhl.

When moving the movable contacts of selector 2 to contact X 5, the magnetic flux increases, which is directed in accordance with the flux of the main winding.

The proposed three-phase switch allows changing the direction of the magnetic flux of the regulating winding (RO) after the reversal, which occurs when the contacts of the pre-selector switch to the fixed contact X 13, which increases the range of adjustment of the switch.

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Claims (4)

1. A three-phase branch switch of transformer windings under load, which contains a case made of a dielectric with a bottom and a cover, contactor mechanisms with switching and additional contacts forming contact groups, and resistors installed in the case, fixed contacts located on the walls of the case and with connected to a transformer and phase branch selectors, a switching mechanism, which differs in that the three-phase contactor mechanisms are installed in one housing, and their contact groups are phase-shifted relative to each other along the axis of the housing by installing one or two phases on dielectric supports. 2. The switch according to claim 1, which differs in that resistors are used as supports, located in dielectric housings and installed under the contact groups, remote from the bottom of the housing. Q. The switch according to claims 1-2, which differs in that dielectric partitions are installed between the phase contactor mechanisms. 4. The switch according to claims 1-3, which is characterized by the fact that the branch selectors of the three phases are placed in one housing, and their contacts are located in planes separated by phase from each other by a distance corresponding to the interphase insulation distance.