BG113306A - Three-phase on-load tap changer for distribution transformers - Google Patents

Abstract

The on-load tap changer comprises a carrier head (1), an insulating cylinder of two sectors (2, 3) and a bottom (4). On the cylinder axis are located one main vacuum arc-suppression chamber (V1) and one supplementary vacuum arc-suppression chamber (V2) for each phase (X, Y, Z). On the inverted mirror imaged (V1 and V2) are mounted radial contact bridges (27, 28) that contact the U-shaped fixed contact elements (29) located on the periphery of the insulation cylinder (2, 3). The movable contact terminals of (V1 and V2) also have radial contact bridges (39) and an opening and closing system of (V1 and V2). The three main vacuum arc-suppression chambers (V1) are secured to an insulation sector (25) by a pipe connected to a Maltese gear (21) located in the carrier head (1). The supplementary vacuum arc-suppression chambers (V2) are also secured to a second insulation sector (22) carrying resistors (R) and connected to a second Maltese gear (24). The two Maltese gears are rotated in two-step switching by two angled rollers (13) of double transmission (12), which is driven unevenly by springs (10) via a disc (9) and a worm gear (11-14). The output shaft (15) is directly coupled to a motor-driven drive shaft. The on-load tap changer can be mounted vertically or horizontally in the transformer. It can be used both in linear regulating winding coil and in coils interrupted in the middle. There is on embodiment wherein the on-load tap changer can be removed for supervision without opening the transformer.

Description

(54) STEP VOLTAGE REGULATOR FOR DISTRIBUTION TRANSFORMERS

FIELD OF THE INVENTION

The invention relates to a three-phase step voltage regulator operating as a selected load, used to regulate the voltage under load of transformers with relatively low power. Vacuum arc quenching chambers can be used in such step regulators.

BACKGROUND OF THE INVENTION

A step controller (1) is known with an electrical control circuit under load interrupted in the middle. It has a contact bridge of two main arc-quenching contacts and a contact bridge of two auxiliary arc-quenching contacts with a resistor connected between them. The switching according to this scheme is done (2) by means of a two-stage spring-energy accumulator, which contains one main spring with levers connected by a vertical insulating shaft, which carries the main contact bridge and an auxiliary spring, with levers connected by a vertical insulating shaft, which carries the auxiliary contact. bridge with resistors. A two-step switching is performed. The step controller is three-phase with three phases located one below the other in an insulating cylinder attached to a support head (3). This step regulator is built into the oil space of a distribution transformer.

The disadvantage of this step regulator is that there is no option with vacuum arc chambers. Another disadvantage is that it cannot be used for a linear control circuit. Another disadvantage is that the spring-energy battery is complex and difficult to adjust.

Another step regulator (4) is known, in which there is one main vacuum arc quenching chamber and one auxiliary vacuum arc quenching chamber in phase, connected by a current limiting resistor. It also works with two-stage switching. Even and odd Malian wheels and a double translation with two rollers are used, which switches them one after the other. Two vertical insulating shafts are rotated by gear pairs, on which the main vacuum arc quenching chambers and the auxiliary vacuum arc quenching chambers for the three phases are mounted separately. The supporting structure consists of a supporting head, a vertical insulating cylinder and a bottom. The mechanisms are located in the support head, and U-shaped fixed contact elements, which can be 10 or more in number, are mounted on the inner surface of the insulating cylinder. There are also movable contact bridges that connect in a certain order these fixed contact elements with vacuum arc quenching chambers. There is also an additional Maltese gear, which moves an externally located pre-selector via a lever system.

The disadvantage of this step regulator is that it is complex and with large dimensions, which does not ensure the task set here to have a small step regulator for distribution transformers. The main vacuum arc quenching chamber and the auxiliary vacuum arc quenching chamber are located next to each other, and the fixed contact elements can be more than 10 pieces. This increases the diameter and transverse gauge of the insulating cylinder. The mechanisms are more and more complex due to the fact that there are variants with different number of positions and side selector.

A step regulator (5) for distribution transformers with a more special construction is also known. It has only one vacuum phase arc quenching chamber and a two-stage selector. There is no spring-free battery, and the quick switching is done by a mechanical system. It is mounted under the cover, above the active part of the distribution transformer, and the electrical system is in a separate box.

The disadvantage of this step regulator is that it does not provide vertical installation, and its placement under the transformer cover complicates the installation of bushings for medium and low voltage. Another disadvantage is that switching the vacuum arc quenching chamber twice in one switch reduces the electrical life, and the lack of a spring-loaded battery can create problems in the event of a sudden power outage during the switch.

Another disadvantage is that the mechanical system and the electrical system of the motor drive are separated, which complicates the revisions and does not meet the requirements of the standard. In order to make an inspection and possible repair, the power supply must be switched off and the transformer must be opened. Another disadvantage is that it does not adjust in a circuit with a break in the middle.

SUMMARY OF THE INVENTION

The object of the invention is to provide a three-phase step voltage regulator for distribution transformers, which has a simplified construction and small dimensions and weight. To be able to work both with a linear regulation scheme and with one interrupted in the middle. Be able to be built into the transformer, both horizontally and vertically. There should also be an option with an oil-sealed oil container and the possibility for revision without opening the transformer.

The problem is solved with a three-phase step voltage regulator, working as a selector under load, containing an oil vessel consisting of a bearing head, an insulating cylinder and a bottom. In the bearing head there is a spring-energy accumulator and a double gear with Maltese wheels. There is one main vacuum arc quenching chamber and one auxiliary vacuum arc quenching chamber which are connected by resistors for each phase. The three main vacuum arc quenching chambers are mounted on an insulating shaft, and the three auxiliary vacuum arc quenching chambers are mounted on a second insulating shaft located parallel to the first. On the inner surface of the insulating cylinder, at equal angular distances, fixed contact elements are mounted, which contact with movable contact bridges connecting them alternately with the vacuum arc-quenching chambers.

According to the invention, a main vacuum arc quenching chamber and an auxiliary vacuum arc quenching chamber for each phase are arranged on the axis of an insulating cylinder, mirrored one below the other, with adjacent fixed terminals to which radial contact bridges are attached. They contact U-shaped fixed contact elements mounted at equal angles on the inner surface of the insulating cylinder. The movable contact terminals of the vacuum arc quenching chambers also have radial contact bridges which contact the drain rings. The three main vacuum arc quenching chambers of the three phases are attached to an insulating segment of pipe, and the three auxiliary vacuum arc quenching chambers are attached to a second insulating segment on which a resistor is mounted. Each segment is connected to a Maltese wheel mounted in a support head. The two Maltese wheels are rotated in two successive steps by two double-shifted rollers of double gear, which interact with a spring-energy accumulator. This battery is charged by a worm wheel connected to a worm, part of the output shaft of the step regulator.

The movable contact terminal of each vacuum arc-quenching chamber has a rocker, a flexible connection and contact springs, the rocker having a roller which, when switching, contacts the front teeth of an insulating disk and opens the respective vacuum arc-quenching chamber. The adjustment of the contact solution of the chamber is done by a special sliding connection mounted on the rocker.

The worm wheel has a tooth that interacts with a tooth on a disk that stretches the switching springs. The connection between this disk and the double translation is made through two of their teeth in a coupling with an angular clearance.

The step controller can regulate under load both transformers with a linear control winding and those with a control winding interrupted in the middle. In this case, the two contact bridges connected to the two terminals of the respective vacuum arc quenching chamber are displaced at an angle of 36 ° and contact two adjacent fixed contact elements. In the auxiliary chamber, the connection between the two contact bridges is broken and the resistor is switched on.

The step controller can be mounted vertically to the active part of the transformer or horizontally above the active part, under the cover.

The described step regulator can be built into an additional oil-sealed oil vessel, consisting of a support head, an insulating cylinder and a bottom. The mechanisms are mounted on a bearing flange, under which a contact system is attached. It is electrically connected to terminal contact elements mounted on the periphery of the insulating cylinder via plug contact assemblies. The inner part can be removed by removing the inspection cover by pulling out the bearing flange.

An advantage of the step voltage regulator according to the invention is that it has a simple construction with small dimensions and weight, suitable for installation in distribution transformers. Another advantage is that it can work both in a circuit with a linear control coil and in a circuit with a discontinuous control coil in the middle. Another advantage is that the step controller can be mounted both vertically and horizontally. Another advantage is that there is an option for the step controller to be removed for revision without opening the transformer.

EXPLANATION OF THE ATTACHED FIGURES

An exemplary embodiment of the step voltage regulator for distribution transformers according to the invention is shown in the attached figures, of which:

Figure 1 represents the two electrical circuits through which the step regulator can regulate the voltage under load:

a) Linear diagram;

b) Scheme with interrupted in the middle regulation winding.

Figure 2 - two possible ways of installation of the step regulator in the boiler of the distribution transformer:

a) Vertical mounting;

b) Horizontal mounting.

Figure 3 - longitudinal section through the step regulator and six cross sections.

Figure 4 - variant in which the step regulator is built into an oil-sealed oil container and can be removed for revision.

EXAMPLES OF EMBODIMENT OF THE INVENTION

Shown in FIG. 1, (a) a linear load control circuit comprises a main winding A, a control winding B, with contact elements C connected to the deviations of the control winding, a line terminal D, a main vacuum arc quenching chamber VI and an auxiliary vacuum arc quenching chamber V2 connected in series with resistor R. This is an electrical circuit of one phase, and the other two phases are like it and are not shown. Most often, the three phases are isolated from each other and connected in triangles. In this case, 9 steps can be switched.

The scheme shown in FIG. 1, b) has a control winding B interrupted in the middle, which in this case provides a range of ± 4 steps. It is characteristic of the step controller according to the invention that with small structural changes of the contact system, both one and the other circuit can be used.

In FIG. 2 shows two possible variants for installation of the step regulator E in the schematically shown boiler F of the distribution transformer. The support head H (pos. A) of the step controller is mounted on the cover K of the transformer, to which, as is customary, the active part L is attached. The motor drive M is also attached to the cover K and is connected to the support head by a shaft N. An advantage of this variant is that it does not change the way of installation of the not shown through terminals for medium and low voltage.

In FIG. 2, b) the step controller E is mounted horizontally under the cover K of the transformer. The bearing head H is the same, but with a slightly modified construction. It is connected to the motor drive by means of an angular gear P.

In FIG. 3 shows the construction of the step controller, in the case of vertical mounting. Carrying are the head 1, the insulating cylinder consisting of two segments 2 and 3, to facilitate installation, and the bottom 4. The supporting head 1 consists of a housing 5 with a flange 6 and a cover 7. Inside the head there is a vertical axis 8 on which are mounted a disk 9 connected to one end of a switching spring 10, a worm gear 11 and a double gear 12 with two drive rollers 13 located at a certain angle to each other on both sides of the double gear 12. The worm wheel 11 is driven by a worm 14 part of the shaft 15, which is connected to the motor drive (Fig. 2). The interaction between the worm wheel 11 and the disk 9 to tension the switching springs 10 takes place through the two teeth 16 and 17 (solution B-B). The interaction between the disc and the double translation takes place through the two teeth 18 and 19 (solution C-C), between which a free stroke is provided 20. In the center, along the axis of the oil vessel, on the housing 5 is mounted a lower Maltese wheel 21 segment 22 of insulating pipe. In this Maltese wheel is mounted a shaft 23 on which are mounted an upper Maltese wheel 24 connected to a second segment 25 and a digital disk 26.

Three auxiliary vacuum arc chambers V2 are mounted to segment 22, one for each phase X, Y, Z. Three main vacuum arc chambers VI, mirrored to V2, are mounted to segment 25. Phases X and Y implement the scheme of FIG. 1, a) (solution D-D). In order to reduce the number of drawings of phase Z, a construction realizing the scheme of FIG. 1, b) (solution EE). The fixed terminal of the vacuum arc chamber VI is connected to a contact bridge 27, and the adjacent fixed terminal of the vacuum arc chamber V2 is connected to a contact bridge 28. This bridge is isolated from V2 and a resistor R is connected between it and V2, which is fixed of segment 22. In phases X and Y the two bridges are located below each other in a static position and are in contact with one of the ten U-shaped fixed contact elements 29 fixed at equal angular distances on the inner surface of the insulating cylinder composed of segments 2 and 3. The terminal 30 of the movable contact element of each vacuum arc chamber is connected to a rocker 31 with a roller 32 which contacts an insulating disk 33 with front teeth 34. The rocker 31 is connected to the terminal 30 by rollers 35 and has contact springs 36 and flexible connection 37. The adjustment of the contact solution of the vacuum arc quenching chamber is done by a special sliding connection 38 mounted on the rocker 31. The flexible connection 37 is connected with a contact bridge 39 which is in contact with a discharge ring 40 with a terminal 41. The terminals 41 of the vacuum arc quenching chamber VI and the vacuum arc quenching chamber V2 are connected to an external conductor 42.

How is the scheme from FIG. 1, b) can be seen in phase Z and section E-E. Two contact bridges 43 and 44 are connected to the two terminals of the vacuum arc extinguishing chamber VI and are mounted on two adjacent Figured fixed contact elements 45 (in this case located at an angle of 36 °). Similar contact bridges are mounted on the two terminals of the vacuum arc chamber V2, but a resistor R is connected between them. 22 and 25 are mounted on an axle 47 mounted on the bottom 4.

The step controller of FIG. 3 is located in the oil space of the distribution transformer and does not have a separate oil, as is the case with the step regulators of power transformers. In order to revise the step controller, the transformer must be opened. In FIG. 4 shows a variant in which the step controller of FIG. 3 is placed in an oil-sealed vessel consisting of a support head I. an insulating cylinder 2 and a bottom 3. The support head 1 has a housing 4 with a flange 5 and a cover 6. The contact systems 7 of the step regulator of FIG. 3 are fixed under a bearing flange 8, on which the mechanisms marked with the same numbers as those of FIG. 3. The support head of the step controller of FIG. 3 dropped out. The fixed end of the switching springs 10 is attached to a column 9 mounted on the support flange 8. To make a revision when the transformer is off, remove the cover 6 and remove the support flange 8 together with the mechanisms and contact systems 7. The electrical connection is made by ten plug contacts A for each phase X, Y, Z and one or more plug contacts B for the current terminal.

The operation of the step regulator is as follows:

The drive shaft of the motor drive is connected to the input shaft 15 (Fig. 3) of the step controller. The worm 17 rotates the worm wheel 11 one turn. Through the tooth 16 of the worm wheel 11 is rotated, with the help of the tooth 17, the disk 9 and the switching springs are tightened. When a dead center of the carrier at the movable end of the spring is passed, the energy in it is released. A tooth 18 on a disk 9 rotates abruptly a tooth 19 of the double translation 13, which rotates 180 °. The two translation rollers 13 successively move the two Maltese wheels 21 and 24 in an angular step of 36 °. Thus, the segment 22 rotates the three auxiliary vacuum arc quenching chambers V2, and the segment 25 rotates the three main vacuum arc quenching chambers VI. The movable contact bridges 27 and 28 successively pass to the adjacent fixed contact member 29. The roller 32 of the respective rocker 31 through the tooth 34 of the disc 33 opens the respective vacuum arc quenching chamber when rotating and passing from one fixed contact element to the adjacent joint becomes currentless. This is how the power switching takes place.

When adjusting in a coil interrupted in the middle (Fig. 1, b), the two contact bridges 43 and 44 (Fig. 3, solution EE, phase Z) of the main vacuum arc quenching chambers and then of the auxiliary vacuum arc quenching chambers are switched in series. . In reverse switching, the sequence is reversed.

Claims (6)

1. A step voltage regulator for distribution transformers, comprising an oil vessel consisting of a support head, an insulating cylinder and a bottom, a spring energy accumulator and a double transfer is Maltese wheels located in the support head, one main vacuum arc chamber and one auxiliary chamber connected to a phase resistor mounted on two insulating shafts performing two-stage switching, fixed contact elements located on the inner surface of the insulating cylinder and movable contact bridges connecting these contact elements to the vacuum arc-quenching chambers, characterized in that the main vacuum arc chamber (V1) and the auxiliary vacuum arc quenching chamber (V2) of each phase (X, Y, Z) are located on the axis of an insulating cylinder (2, 3) mirrored one below the other with adjacent fixed contact terminals to which radial contact bridges are attached. (27, 28) in contact with U-shaped fixed contacts elements (29) mounted at equal angles on the inner surface of the insulating cylinder (2, 3), the movable contact terminals of the vacuum arc quenching chambers (VI, V2) also have radial contact bridges (39) in contact with drain rings (40), such as the three main vacuum arc quenching chambers (VI) of the three phases (X, Y, Z) are attached to an insulating segment (25) of pipe, and the three auxiliary vacuum arc quenching chambers (V2) are attached to a second insulating segment (22) on which a resistor (R) is also engaged, the segment (25) is connected to a Maltese wheel (21) mounted in the support head (1), and the segment (22) is connected to a second Maltese wheel (24), the two Maltese wheels rotating in two steps of two rollers (13) of double translation (12), which interact with the worm wheel (11) with a worm (14) of an output shaft (14) directly coupled to a motor-driven drive shaft. Step voltage regulator according to claim 1, characterized in that the movable contact terminal (30) of each vacuum arc quenching chamber (VI, V2) has a rocker (31), a flexible connection (37) and contact springs (36), the rocker (31) having a roller (32) which, when switched, contacts the front teeth (34) of an insulating disk (33) and opens the corresponding vacuum arc-quenching chamber, and the adjustment of the contact solution is done by a special sliding connection (38) established. of the rocker (31). Step voltage regulator according to claims 1 and 2, characterized in that the worm wheel (11) has a tooth (16) which interacts with a tooth (17) on a disk (9) which stretches the springs (10), and the connection between the disk (9) and the double translation (12) is made through the teeth (18 and 19) of a coupling with an angular clearance (20). Step voltage regulator according to Claims 1, 2 and 3, characterized in that it can regulate under load, both in the case of a linear control winding and in the case of a control winding interrupted in the middle, in which case the two contact bridges (44 and 43) connected to the two terminals of the vacuum arc chambers (V1 and V2) are displaced at an angle of 36 ° and contact two adjacent fixed contact elements (29), and in the auxiliary vacuum arc chambers (V2) the connection between the two contact bridges and 43) is disconnected and there is a resistor (R) connected. Step voltage regulator according to claims 1, 2, 3 and 4, characterized in that it can be mounted vertically to the active part of the distribution transformer or horizontally above the active part and under the transformer cover. Step voltage regulator according to claims 1, 2, 3, 4 and 5, characterized in that the step regulator of FIG. 3 can be installed in another oil-sealed container (Fig. 5) consisting of a support head (1), an insulating cylinder (2) and a bottom (3), the mechanisms being mounted on a support flange (8), under which it is fixed. contact system (7), which is electrically connected to the terminals of the insulating cylinder (2) by plug contact assemblies (A, B), and the removal for revision is done by pulling the flange (8) with the cover (6) removed.