BG113376A - Load tap changer for step voltage regulator - Google Patents

Abstract

The supporting structure of the selector is composed of an upper body (8), an insulating cylinder (1) and a round bottom (5). An insulating tube (14) is located axially in the middle, on which even (16) and odd (17) contact rings are arranged. In the housing (8) around the tube (14) are mounted even (9) and odd (10) Maltese wheels, which are driven alternately by a double translation (11) connected to a drive shaft (12). Staggered even (2) and odd (3) stationary contact elements are mounted on the insulating cylinder (1). The connection between these elements and the fixed contact rings (16, 17) is made by contact lamellae (18) located on insulating rails (21, 24), which are respectively connected to the Maltese wheels (9, 10). Wires (27) connected to the contact rings (16, 17) pass through the pipe (14). It is characteristic that the insulating cylinder (1) is whole and thin-walled. It is connected to the housing (8) through an upper ring (4), providing the possibility of circumferential rotation. Thus, the assembly is carried out with the contact lamellas (18) rotated in relation to the contact elements (2, 3). Then by turning the cylinder (1) the normal contact is realized. The control is carried out through the holes on the bottom (5). Also, the fixed contact elements (2, 3) are made of rod material by turning, with the possibility of having two or four contact points, according to the regulated rated current.

Description

VOLTAGE STEP REGULATOR SELECTOR

FIELD OF ENGINEERING

The invention relates to step voltage regulators. They are complex electromechanical products that are built into power transformers in order to regulate the voltage of consumers under load, i.e. without interrupting the power supply. Step regulators are most often composed of several main components - an oil pan, a power switch, a selector and a pre-selector. The selector has a certain number of contact nodes to which the deviations from the regulation winding of the transformer are connected. The movable contact system of the selector selects specific deviations depending on the commands of an automatic regulator.

PRIOR ART

A step voltage regulator selector (1) is known comprising a bearing head with a Maltese mechanism and a bottom flange, between which five vertical insulating bars of rectangular cross-section are fixed. Six fixed contact nodes are mounted on each floor level, one even and one odd per phase. In the middle of the selector is located a central insulating tube clamped to the bearing head and flange. Six contact rings, one even and one odd per phase, are fixed around the tube in tiers. Attached to each ring is a current-carrying wire that runs vertically up inside the tube. The wires are wrapped with insulating tape. Fixed contact assemblies are composed of a contact element made of rod material and two shields with a complex shape. The even stationary contact elements and the even contact rings are connected by contact plates carried by an even vertical drive shaft attached to an even Malt wheel. The construction of the odd current-carrying loop is also analogous. The contact plates are of a complex shape providing four each

1/7 contact points to the stationary contact element and to the contact ring.

The disadvantage of this chosen one is that it is of increased height and insufficient stability, since it is supported on only five slats, which must be of increased cross-section and have no curvature. Another disadvantage is that the contact elements are complicated. A disadvantage is that the wires in the central tube are bandaged, as a result of which their cooling is significantly impaired.

A step voltage regulator selector (2) is also known, which also has a bearing head with a Maltese mechanism and a bottom flange. They are connected by five insulating columns composed of two insulating rails. The fixed contact elements are made of castings and are arranged in a zigzag pattern on the outer sides of the two rails. Thus, the isolation distances are increased and the height of the selector is reduced. Stability is also improved. There is also a central insulating tube with six contact rings connected by braided wires inside the tube. Even and odd vertical drive isolation shafts connected to Maltese wheels carry movable contact plates. They are two for smaller currents and four for higher currents.

A disadvantage of this selector is that the insulation columns are complicated, since the two insulation rails are additionally strengthened by insulation elements. A disadvantage is that the insulation distances between the fixed contact elements are unevenly distributed, which is why a larger diameter may be necessary in some selectors. Another disadvantage is that the fixed contact elements are made of cast iron, which increases their cost. Also a disadvantage is that the wires in the central tube are bandaged, as a result of which their cooling is impaired.

A third step voltage regulator selector (3) is also known, which also has a bearing head with a Maltese mechanism and a bottom flange. They are interconnected by five insulating segments cut from an insulating cylinder. Three even and three odd fixed contact elements are mounted on each segment, arranged in a zigzag pattern. Each contact element is made of rod material and has two contact rollers located side by side along its axis. The six contact rings are attached to three insulating rails located radially at 120°. The current-carrying wires are attached to the contacts

2/7 rings and are mounted in insulating tubes. With increased requirements for insulation, they are bandaged. There is only one Maltese wheel and one vertical isolation drive shaft. The movable contact system is shaped like a bridge. This one was selected with a simplified construction and increased resistance of the isolation cage. At the same time, it is designed for smaller nominal currents and insulation parameters. The disadvantage is that the fixed contact nodes are complicated. Another disadvantage is that after cutting the insulating cylinder into segments, they may undergo certain deformations as a result of internal stresses obtained during the winding of the cylinder.

TECHNICAL ESSENCE OF THE INVENTION

The task of the invention is to create a selector for a step voltage regulator, which has a simplified construction, with reduced overall dimensions, weight and cost, is strong and stable and at the same time has high technical parameters. To have unified performances for a range of technical parameters.

The task is solved with a selector for a step voltage regulator containing a bearing head with a Maltese mechanism and a lower flange connected by a circular cage of insulating segments. Even and odd fixed contact nodes are installed on them. In the center of the selector there is a central insulating tube with even and odd contact rings stacked around it. These rings are connected to the fixed contact units by means of contact lamellae attached to vertical insulating shafts driven by the Maltese mechanism. Inside the central insulating tube are insulated wires connected to the contact rings.

According to the invention, the cage of segments is replaced by a whole thin-walled insulating cylinder mounted separately on an upper metal ring and a lower flange. Even contact assemblies and odd contact assemblies mounted on the periphery of the insulating cylinder have a spherically shaped contact surface and are secured to the insulating cylinder by an inner plastic washer, an outer plastic washer and a nut. The faces of the contact rings are formed with arcuate contact surfaces so that the two contact lamellae contact the convex surfaces of the contact rings and the fixed contact elements. On the top ring of the insulating cylinder there are tangential arcuate grooves into which bolts enter

3/7 connecting ring and bearing head. The channels allow up to 15° rotation of the isolation cylinder during its assembly to the bearing head. Thus, during assembly, the movable contact lamellae are diverged from the fixed contact nodes, and then by rotating the cylinder, contact is achieved.

The contact rings and wires in the center tube are connected by lugs and a screw connection, mostly with bolts. The conductors are placed in insulating tubes with a slightly larger internal diameter so that there are oil passages for the circulation of the transformer oil. On the upper ends of the wires in the central tube, radial wires are fixed by means of a screw connection.

The contact plate has two mutually perpendicular channels formed at an angle on both ends, which ensure contact of two contact points on both ends of the plate. This is an option when higher rated currents are required. For smaller rated currents, a simplified variant with flat contact plates, with one contact point each, can be used. Two contact points on the spherical contact surface of the stationary contact element can alternatively be achieved by means of two oppositely angled channels. In this case, the contact faces of the lamellae are flat.

An advantage of the step voltage regulator selector is that it is stable due to the use of an entire insulating cylinder. It is thin-walled with simplified processing, which reduces the cost. It is also an advantage that the fixing of the fixed contact assemblies is stable, as inner and outer plastic pads with a one-sided curvature that matches the curvature of the cylinder are used. The pads are cheap because they are produced by injection molding.

Another advantage is that contact systems for larger and smaller currents can be provided with minor changes.

It is also an advantage that the wires in the center tube are not banded and are cooled directly by the transformer oil. If required to provide greater insulation strength between the contact elements, longitudinal grooves could be cut on the insulation cylinder, providing additional oil insulation.

4/7

EXPLANATION OF THE ATTACHED FIGURES

An exemplary embodiment of a step voltage regulator selected according to the invention is shown in the attached figures, from which:

Figure 1 is a longitudinal section through a selected.

Figure 2 - a cross-section through a two-level (А-А and В-В) selection.

Figure 3 - longitudinal section through the contact system on an enlarged scale.

Figure 4 - cross section through the contact system of fig. 3.

Figure 5 - variants of contacting with the fixed contact node.

EXAMPLES OF IMPLEMENTATION OF THE INVENTION

In fig. 1 and fig. 2 shows a three-phase selector for adjustment in a star center. On the periphery of an entire insulating cylinder 1 with a reduced thickness (approximately 5 mm), even fixed contact elements 2 and odd fixed contact elements 3 are arranged in tiers. The cylinder 1 has a metal ring 4 on its upper face, and a flange 5 on its lower face with three or four radial ribs 6. The ring 4 is fixed by means of bolts 7 to a bearing head 8, in which is mounted a known Maltese mechanism consisting of an even Maltese wheel 9, an odd Maltese wheel 10 and a double translation 11 mounted on a drive shaft 12. On the ring 4 has a certain number of tangential grooves 13 (for example, 6 pcs.) in which the bolts 7 enter. These grooves allow a certain angular rotation (for example, up to 15°) between the ring 4 and the bearing head 8 to be achieved during assembly. Axis in the center on the selector there is an insulating tube 14 fixed between the supporting head 8 and a support shaft 15 mounted on the flange 5. Even contact rings 16 and odd contact rings 16 are arranged around the tube 14 and fixed to it contact rings 17.

Even contact elements 2 and even contact rings 16 are connected by contact slats 18 with contact springs 19. The slats 18 are attached to carriers 20, which are mounted on two vertical insulating rails 21. At their upper end, the rails 21 are connected to an arm 22 mounted to the even Maltese wheel 9, and at its lower end to a shoulder

5/7

23, bearing on the support shaft 15. In an analogous way, the odd contact elements 3 and the odd contact rings 17 are connected by the same contact lamellae 18, fixed to carriers 20, which are mounted on two insulating rails 24. These rails are connected at their upper end with an arm 25 mounted to the odd Maltese wheel 10, and at its lower end to an arm 26 bearing on the supporting shaft 15. To each contact ring 16 and 17 is connected a current-carrying conductor 27 mounted in an insulating tube 28 and passing vertically upwards in the central tube 14. The tubes 28 are supported at their lower end to a disk 29 centering the tube 14.

At their upper end, the conductors 27 are connected to horizontal current-carrying conductors 30, which are connected in a known manner to a known current-carrying system of a power switch. The two Maltese wheels 9 and 10 are mounted on a bearing sleeve 31. If rolling bearings are used, the bearing of the Maltese wheels can be done directly on the insulating tube 14. If it is necessary to increase the insulating strength on the surface of the cylinder 1, it can be vertical channels 32 providing an oil gap are cut. Position 33 indicates the position of the lamellae 18 when rotated during installation.

Details of the contact system of the selector can be seen in Figures 3 and 4 presented on an enlarged scale. The positions of Figures 1 and 2 are the same. What's new is the following.

The fixed contact element 2 has a spherically shaped contact surface and a tail 34 with an opening 35 for connecting the wires from the regulation winding of the transformer. The fastening of the contact element 2 to the relatively thin wall of the insulating cylinder 1 takes place by means of an inner plastic pad 36, an outer plastic pad 37 and a compression nut 38. The contact ring 16 also has spherically shaped edges. At the end of the contact lamellae 18, grooves are made so that four contact spots are obtained instead of two, as a result of which overheating is reduced and thermodynamic resistance is increased. Between the two vertical insulating rails 21, a carrier 20 is fixed, on which the contact lamellae 18 are mounted by studs 39. They are pressed against the contact element 2 and the contact ring 16 by means of the springs 19. At the lower end of the current-carrying conductor 27, a tip 40 is held by means of a bolt 41. The tip 40 is connected to the contact ring 16 in a known manner by one or two bolts shown by a broken line.

6/7

In fig. 5, three variants of the contact lamellae 18 are presented. The variant from position "a" is for larger operating currents, as it provides four contact points. It combines with that shown in fig. 3 and is relatively more complex to implement. The variant of position "b" is simpler, but it is for relatively smaller operating currents. In this case, there are only two contact points on the contact ring 16 because there is no channel on the contact lamella 18. The variant of position "c" is hybrid and also provides four contact points because two channels 42 are made on the contact element 2.

The voter's action is as follows. The drive shaft 12 is rotated 180° and the double translation 11 rotates, for example, the even Maltese wheel 9 by one step via the arm 22 and the insulating rails 21 with the even contact lamellae 18 are moved to the adjacent stationary contact element 2. On the next rotation of the double translation 11 rotates the odd Maltese wheel 10 and moves the odd contact lamellae 18 via arm 25 and rails 24, to the adjacent odd fixed contact element 3.

It is important to see how the assembly of the selector will be done, because since the isolation cylinder 1 is whole, access inside it will be difficult. This is realized in the following way. Separately, the metal ring 4 and the flange 5 are mounted on the insulating cylinder. Then the fixed contact elements 2 and 3 are mounted, which is easy because there is nothing inside the cylinder. The supporting head 8 with the mechanisms in it and the central insulating tube 14 with the contact rings 16 and 17 and the wires 27 and the insulating tubes 28 are installed separately. Next is the installation of the insulating rails 21 and 24 with the movable contact slats 18 attached to them. Next, the central part in a 15° rotated position (position 33) is lowered into the installed insulating cylinder 1, the metal ring 4 being connected to the bearing head 8 by means of bolts 7 with washers, and they are not wound all the way. A stable bearing of the arms 23 and 26 to the shaft 15 is ensured. The cylinder 1 is rotated back by 15° so that a stable contact is obtained between the fixed contact elements 2 and 3 with the movable contact lamellae 18. The contact is controlled through the holes in the flange 5 and the vertical channels 32. After the necessary checks, the bolts 7 are tightened and secured by suitable washers.

Claims (5)

PATENT CLAIMS 1. Selector for a step voltage regulator comprising a bearing head with a Maltese mechanism and a bottom flange which are connected by a circular cage of insulating segments with even and odd fixed contact assemblies mounted thereon, in the center of the selector there is a central insulating tube with tiered around it, even and odd contact rings, as they are connected to the fixed contact assemblies by contact lamellae attached to vertical insulating shafts driven by the Maltese mechanism, and inside the central insulating tube are located insulated wires connected to the contact rings, characterized in that the cage of segments is replaced by a whole thin-walled insulating cylinder (1) mounted separately on an upper metal ring (4) and a lower flange (5), with fixed even contact nodes (2) and odd contact nodes mounted on the periphery of the insulating cylinder (1) (3) have a spherically shaped contact surface and are attached to the insulating cylinder (1) by inner plastic washer (36), outer plastic washer (37) and nut (38), the faces of the contact rings (16) are formed with arcuate convex surfaces so that the two contact lamellae (18) contact the convex surfaces of the contact rings (16) ) and the fixed contact elements (2,3), and the ring (4) has arcuate tangential channels (13) into which the bolts (7) connecting the ring (4) and the bearing head (8) and allowing rotation between them during of the installation. 2. Selector for step voltage regulator according to claim 1, characterized in that the rings (16) and the wires (27) in the central tube (14) are connected by lugs (40) and bolts (41), and the wires ( 27) are located in insulating tubes (28), with oil channels between them and the wires (27). 3. Selector for a step voltage regulator according to claims 1 and 2, characterized in that the horizontal current-carrying wires (30) are connected to the vertical wires (27) at their upper faces by means of bolts. 4. Selector for a step voltage regulator, according to claims 1, 2 and 3, characterized in that the contact plate (18) has two mutually perpendicular angular channels at both ends ensuring contact of the plate (18) with the face of the contact ring (16) at two contact points, respectively - contact of the plate (18) with the sphere of the fixed contact element (2, 3) at two contact points. 5. Selected as a step voltage regulator according to claims 1, 2 and 3, characterized in that on the spherical surface of the stationary contact element (2, 3) there are two opposite angular channels (42) through which four contact places.