BG112739A - Three-phase on-load tap changer withmotor drive for distribution transformers - Google Patents

Abstract

The on-load tap changer comprises a carrier head (1), aninsulating cylinder of two sectors (2, 3) and a bottom (4). On thecylinder 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 (V1and V2) are mounted radial contact bridges (27, 28) that contact theU-shaped fixed contact elements (29) located on the periphery of theinsulation cylinder (2, 3). The movable contact terminals of (V1 andV2) also have radial contact bridges (39) and an opening and closingsystem of (V1 and V2). The three main vacuum arc-suppressionchambers (V1) are secured to an insulation sector (25) by a pipeconnected to a Maltese gear (21) located in the carrier head (1). Thesupplementary vacuum arc-suppression chambers (V2) are alsosecured to a second insulation sector (22) carrying resistors (R) andconnected to a second Maltese gear (24). The two Maltese gears arerotated in two-step switching by two angled rollers (13) of doubletransmission (12), which is driven unevenly by springs (10) via adisk (9) and a worm gear (11-14). The output shaft (15) is directlycoupled to a motor-driven drive shaft with a motor and belt gearing.The on-load tap changer can be mounted vertically or horizontally in the transformer. It can be used both in linear regulating windingcoil and in coils interrupted in the middle. There is on embodimentwherein the on-load tap changer can be removed for supervisionwithout opening the transformer.

Description

(54) STAGE VOLTAGE REGULATOR WITH MOTOR DRIVE FOR DISTRIBUTION TRANSFORMERS

FIELD OF THE INVENTION

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

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 a three-phase three-phase phase 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 step controller is actuated by a motor drive, which is available in two versions.

1/14

One option is when the mechanical drive system is located in the support head and the electrical system is in a separate box connected to the support head via a cable. There is also a possibility for manual drive with a lever in a safe place. The other option is to use a standard motor drive, which is borrowed from the larger step regulators.

The disadvantage of this step regulator is that there is no option with vacuum arc chambers (VDK). 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. There are also disadvantages in terms of the motor drive that completes it. In the case of the version with a mechanical system in the support head and an electrical system in a separate box, the disadvantages are that for revision of the mechanical system the transformer must be switched off, and also - the requirement of the international standard for step regulators is not met. According to him, the motor drive should be a separate unit. The use of a ready-made motor drive makes the system more expensive.

Another selector under load (4) is known, in which there is one main VDK and one auxiliary VDK per phase, connected by a current-limiting resistor. It also works with two-stage switching. Even and odd Maltese 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 VDK and the auxiliary VDK 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 in number or more, 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 VDK. There is also an additional Maltese gear, which moves an externally located pre-selector via a lever system.

The disadvantage of this voter under load is that it is complex and with large dimensions, which does not ensure the task set here to have a small

2/14 step regulator for distribution transformers. The main VDK and the auxiliary VDK 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 complicated due to the fact that there are variants with different number of positions and side selector.

A step regulator (5) is also known for distribution transformers with a more special construction. It has only one VDK per phase and a two-stage selector. There is no spring-energy battery, and the fast switching is done by the 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 double switching of the VDK in one switch reduces the electrical resource, and the lack of a spring 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. Have a small and simple motor drive that meets the standard. Yes

3/14 there is also a variant with oil-sealed oil tank and 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 an equal angular distance, 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 translation, 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 output shaft is directly coupled to the drive shaft of the motor drive, this shaft being connected to the motor by a large pulley, belt and a small pulley mounted on the motor shaft.

4/14

The movable contact terminal of each vacuum arc 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 corresponding vacuum arc 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 motor drive comprises a worm, part of the drive shaft coupled to a worm wheel, the shaft of which is connected to a command controller. This shaft has a second worm and a helical gear, the shaft of the second worm wheel having an arrow to indicate the positions and actuating a switch. The helical gear is engaged with a second helical wheel, the shaft of which has a di0k, which indicates “normal position.

The switch consists of an insulating sleeve, on the periphery of which there are Hall sensors, and in it rotate carriers with permanent magnets. The command controller can also be contactless with Hall sensors and permanent magnets.

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 connected there.

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 container consisting of a support head, an insulating cylinder and a bottom. The mechanisms are mounted on a bearing flange, under which the contact system is fixed. It is electrically connected to terminal contact elements,

5/14 mounted on the periphery of the insulating cylinder by plug contact assemblies. The inner part can be removed by removing the inspection cover by pulling out the bearing flange.

An advantage of the stepped voltage regulator with motor drive 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 control coil interrupted in the middle. Another advantage is that the step controller can be mounted both vertically and horizontally. It is also an advantage that there is an option for the step controller to be removed for revision without opening the transformer. Another advantage is that the motor drive meets the standard.

EXPLANATION OF THE ATTACHED FIGURES

An exemplary embodiment of a stepped voltage regulator with a motor drive 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) circuit with interrupted regulation winding in the middle.

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- construction of the motor drive, which is an integral part of the step controller.

6/14

Figure 5 - 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 linear control circuit under load comprises a main coil 11, a control coil 12, with contact elements 13 connected to the deviations of the control coil line terminal 14, a main vacuum arc quenching chamber VI and an auxiliary vacuum arc quenching 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 a triangle. In this case, 9 steps can be switched.

The scheme shown in FIG. 1, b has a control winding 12 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 1 in the schematically shown boiler 2 of the distribution transformer. The support head 3 (pos. A) of the step controller is mounted on the cover 4 of the transformer, to which, as is customary, the active part 5 is attached. The motor drive 6 is also attached to the cover 4 and is connected to the support head by a shaft. 7. 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 1 is mounted horizontally under the cover 4 of the transformer. The support head 3 is the same, but with a slightly modified construction. It is connected to the motor drive via an angular gear 3.

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, in order to facilitate installation, and the bottom 4. The supporting head 1

7/14 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 drives 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 a shaft 15, which is connected to the motor drive (Fig. 4). 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 free travel 20 is provided. In the center, along the axis of the oil vessel, on the housing 5 is mounted a lower Maltese wheel 21 connected to 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 suppression chambers V2 are mounted to segment 22, one for each phase X, Y, Z. Three main vacuum arc quenching chambers (VDCs) VI, mirrored to V2, are mounted to segment 25. Phases X and Y implement the scheme of FIG. 1, a (section D-D). To reduce the number of drawings of phase Z, a construction realizing the scheme of FIG. 1, b (section E-E). The fixed terminal of VDK VI is connected to contact bridge 27, and the adjacent fixed terminal of VDK V2 is connected to contact bridge 28. This bridge is isolated from V2 and a resistor R is connected between it and V2, which is attached to segment 22. In phases X and Y, the two bridges are located one below the 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 along the inner surface of the insulating cylinder composed of segments 2 and 3. 30 of the movable contact element of each VDK 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 a flexible connection 37. the contact solution of VDK is made by a special sliding connection 38 mounted on the rocker 31. The flexible connection 37 is connected to a contact bridge 39, which is in contact with a drain ring 40 with terminal 41. Terminals 41 of VDK VI and VDK V2 are connected to an external conductor 42.

8/14

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 VDK VI and are mounted on two adjacent U-shaped fixed contact elements 45 (in this case located at an angle of 36 °). Similar contact bridges are mounted on the two terminals of VDK V2, but a resistor R is connected between them. The U-shaped contact elements 45 of the main VDK VI and of the auxiliary VDK V2 are connected by a wire 46. The lower ends of the two segments 22 and 25 are mounted on axle 47 mounted on the bottom 4.

The construction of the motor drive, which is a part of the step regulator, is presented in Fig. 4. A small three-phase induction motor 3 is mounted on a support plate 1 which is part of a protective box 2. It is coupled to a small toothed pulley 4 mounted on a plate 1 and a housing 5. In the same way a drive shaft 6 bearing is mounted. large toothed belt pulley 7. The two washers are connected to a toothed belt 8. At the front end of the shaft 6 there is a channel 9, to which in manual control an unmarked handle is coupled. Shaft 6 also comprises a worm 10 which is engaged with a worm wheel 11, a shaft 12 on which it is arranged horizontally and is mounted between two brackets 13. The shaft 12 has a gear 14 with inclined teeth and a second worm 15 engaged with a worm wheel. 16. Gear 14 is engaged with a second gear 17 with inclined teeth. The shaft 18 of the worm wheel 16 and the shaft 19 of the gear 17 are arranged horizontally and are mounted between a plate 1 and a smaller plate 20 attached to the brackets 13. On the front face of the shaft 19 there is a pointer 21 to indicate "normal position". On the front face of the shaft 18 there is an arrow 22 to indicate which step is the step regulator and switch 23 consisting of an insulating sleeve 24 and supports 25 of movable contact elements. The contact elements of the switch 23 could be composed of Hall sensors and permanent magnets.

At the end of the shaft 12 is mounted a command controller 26, which may also be composed of Hall sensors and permanent magnets. In the protective box 2, under the electric motor, there is an electrical control panel 27. The electrical circuit can be with contactors or with electronic elements. The protective box 1 is closed with a lid 28.

9/14

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 the power transformers. To revise the step controller, the transformer must be opened. In FIG. 5 shows a variant in which the step regulator of Fig. 3 is placed in an oil-sealed vessel consisting of a support head 1, 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 controller 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 motor drive and the step regulator is as follows:

When the electric motor 3 (Fig. 4) is switched on, the toothed belt drive 4-7-8 reduces the speed of the drive shaft 6. By means of the worm gear 10 - 11 the shaft 12 makes one switching speed. This is provided by the command controller 26. The worm gear 15 -16 drives the shaft 18 in steps of 36 °, the arrow 22 indicating in place the position of the step controller, and the switch 23 providing this remotely.

The drive shaft 6 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. By means of a tooth 16 of the worm wheel 11 it is rotated, by means of a tooth 17, the disk 9 and the switching springs are tightened. When the dead center of the carrier at the movable end of the spring passes, the energy in it is released. Tooth 18 on disk 9 rotates abruptly 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, segment 22 rotates the three auxiliary vacuum arc chambers V2, and segment 25 - the three main vacuum

10/14 arc extinguishing 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 VDK 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 E-E, phase Z) of the main VDK and then of the auxiliary VDK are switched in series. switching sequence is reversed.

Claims (8)

PATENT CLAIMS 1. Motor-operated step voltage regulator for distribution transformers, comprising an oil vessel consisting of a support head, an insulating cylinder and bottom, a spring energy accumulator and a double translation with Maltese wheels located in the support head, one main vacuum arc quenching chamber and one vacuum arc-quenching chamber connected to a resistor, in phase, 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 vacuum arc-quenching chamber (VI) and the auxiliary vacuum arc-quenching chamber (V2) of each phase (X, Y, Z) are arranged along the axis of an insulating cylinder (2, 3) mirrored one below the other with adjacent fixed contact terminals to which they are attached. radial contact bridges (27, 28) in contact with U-shaped fixed contact 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 the drain rings (40) , the three main vacuum arc-quenching chambers (VI) of the three phases (X, Y, Z) being attached to an insulating segment (25) of pipe, and the three auxiliary vacuum arc-quenching chambers (V2) being attached to a second insulating segment (22), on which a resistor (R) is attached, 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 being connected. rotate in two steps by two rollers (13) displaced at a certain angle on a double translation (12), which interacts with a spring energy accumulator (10), and its charging is done by the worm wheel (11) with a worm (14) on an output shaft (14). directly coupled to the drive shaft (6) of the motor drive (Fig. 4), which shaft is connected to the electric motor (3) by a large gear belt (7), a belt (8) and a small gear belt (4). 12/14 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 switching, 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 its motor drive comprises a worm (10), a part of the drive shaft (6) coupled to the worm wheel (11), the shaft of which (12) is connected to a control controller (26) and has a second worm (15) and a helical gear (14), the shaft (18) of the second worm wheel (16) has an arrow (22) to indicate the positions and is connected to a switch ), and the helical gear (14) is coupled to a second helical gear (17), the shaft (19) of which has a disk (21) which indicates' normal position. Motor drive according to claim 4, characterized in that the switch (23) consists of an insulating sleeve (24) with Hall sensors and permanent magnet carriers (25), and the command controller (26) can also be contactless with Hall sensors and permanent magnets. Step voltage regulator according to Claims 1, 2, 3, 4 and 5, 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 both contact bridges (44 and 43) connected to the two terminals of the vacuum arc quenching chambers (VI and 13/14 V2) are displaced at an angle of 36 ° and contact two adjacent fixed contact elements (29), and in the auxiliary vacuum arc quenching chambers (V2) the connection between the two contact bridges (44 and 43) is broken and the resistor (R) is connected there. Step voltage regulator according to claims 1, 2, 3, 4, 5 and 6, 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, 5, 6 and 7, characterized in that the step regulator of FIG. 3 can be installed in another oil-sealed oil 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 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.