HK1207737B - On-load tap changer - Google Patents

Description

The present invention relates to a load step switch for uninterrupted switching between different winding sockets of a step transformer according to the general concept of the first claim.

Load step switches have been used for many years to switch between different winding sockets of step transformers in large numbers worldwide. So-called reactor switches, which are especially common in North America, have a switching reaction that allows for a slow, continuous switching. Load step switches according to the resistance-fast switching principle usually consist of a selector for powerless selection of the respective winding socket of the step transformator to be switched, and a load switch to switch from the current to the new, intermediate switching cycle.

A load-level switch with vacuum switches is shown, for example, in the DE 10 2009 043 171 A1 where a load switch carries a drive shaft driven by a power storage device with at least one curved disc, the curved disc having several control curves, two control curves placed on the front of the control panel having a contour of a different shape from a circle by means of a type of knobs, each of which is connected by a contact wire to a roll connected by a tilt lever to a vacuum switch, which retracts the profile contour of the respective control curve.

In a special class of load switches, the so-called load switches, the means described for selecting a new winding connection and the means for actual load switching are combined and operated together. Usually, step switches are based on the principle of resistance-speed switching for the uninterrupted switching from one connection of a step transformer to another, so that the fixed step contacts electrically connected to the outputs of the step winding are arranged in one or more horizontal planes or insulated planes on a spring or cylinder and are powered by concentric drive waves.

DE 42 37 165 C1 describes, in contrast to these usual designs, a step-change with linear contact action, whereby the fixed step-contacts extend along a track into the inside of the switch and can be actuated by a movable switch mechanism, which in turn is driven by the drive shaft. The vertically actuated switch mechanism consists of a continuously actuated lift shaft by the drive shaft, which pre-selects the new fixed step-change, and a lift slide by means of a retractable energy storage unit, which, after activation of the spring-loaded lift and after the actual load-loading of the components, is the necessary component for the complete development of the new step-change.

The applicant's claim that the applicant's claim for annulment of the contested decision was based on the fact that the applicant had not been able to demonstrate that the applicant had not failed to fulfil its obligations under Article 85 (1) of the Treaty, in so far as it had not been able to demonstrate that the applicant had not failed to fulfil its obligations under Article 85 (1) of the Treaty, was rejected.

US 1 985 927 A further describes a stepper switch for stepper transformers, which has vertically sliding contact plates that select the winding taps of the stepper to be switched. The contact plates are driven by means of a cylinder over a wave. Over this wave, the contacts of the load switch are also actuated. The wave drives a crank connected to the contacts of the switch via draw spring. When the crank turns the load springs are tensioned.

The power storage units are essentially composed of a lifting slide and a spring slide, between which power storage units are arranged as power storage springs. The energy storage units are, for example, the DE 860 551 and the DE 06 281 282 282 Bmbar.

The initial slow rotation of the drive shaft is used to translate a lifting sledge upwards, and then to convert the translational movement of the spring sledge, the downslide, into a rotational main movement of the drive shaft and a related actual contact action.

WO 2004 088 693 A1 describes a stepper motor with a torque motor as the drive, which directly operates both the load switch and the fine-tuning switch.

The present invention is therefore intended to specify a load-level switch which eliminates the complexity of the design of a power storage device and thus provides a significantly simplified design with increased reliability.

This task is solved by a load step switch for uninterrupted switching between different winding taps of a step transformer with the characteristics of the first claim.

The general idea of the invention is to operate both the switchgear and the switches for uninterrupted load switching by means of a common motor drive by means of a threaded spindle arrangement without an energy storage intermittent circuit.

In a preferred embodiment of the invention, the movable contactors are each incorporated into a contact support and interact with fixed contactors placed on a support plate in such a way that the individual fixed contactors can be charged in the longitudinal direction of the spindle by a longitudinal displacement of the movable contactors as part of a common contact unit mechanically connected to the spindle nut.

The following is an illustrative explanation of the invention. It shows: Fig. 1 shows a load switch according to the invention, as shown above.

The basic supporting element for the entire load switcher is a supporting plate 1 of insulating material, directly on which, or, as shown here, on a separate supporting plate 1a, an electric motor 2 is mounted, e.g. a torque motor or a stepper motor. On the support plate 1, fixed switchgear 3 are arranged at equal distances from each other along a linear path, indicated in the figure by a dashed line. The drive motor 2 described above drives an insulating shaft 4It is also possible for the invention that the drive motor 2 directly drives the generally metal thread 5 but the inserted insulating shaft 4 described is useful in many cases for reasons of tensile strength. The thread spindle 5 runs parallel to the track of the fixed connectors 3. It is mounted on two bearings 5.1 and 5.2 and is rotatable and fixed in its position. The thread spindle 5 is supported by a spindle nut 6 which in turn carries a contact unit 7 which is moved along with the spindle nut 6 in both directions, i.e. along the dash line,Err1:Expecting ',' delimiter: line 1 column 253 (char 252)that it is possible to connect two adjacent fixed voting contacts (bridging connection) to one of the mobile voting contacts 9 or 10 or to have both mobile voting contacts 9 and 10 on one of the fixed voting contacts 3. On the support plate 1, parallel to each other and parallel to the track of the fixed connectors 3 and parallel to the threaded spindle 5 along the line of the dashed line shown are the 11 and 12 contact and guide rails of electrically conductive material, which have a dual function: first, they provide the mechanical guidance of the longitudinal connector unit 7.10 of the load switch W to the switching elements of the load switch LU of the load switch; this will be explained in more detail below. At its end facing the drive motor 2, the threaded spindle 5 is mechanically connected to a gear 13 whose other side has another rotatable insulating shaft 14 which is rotatably supported and fixed in its position by two more bearings 14.1 and 14.2. A camshaft 15 (or a similar control device with similar functionality) shall be fixed on the isolation shaft 14.

On either side of the insulation shaft 14 are the actuators of the LU load switch, here two vacuum switching tubes 16 and 17, each operated by a control roller 18 or 19, running on a contour of the camshaft 15. It is possible, in the context of the invention, that both control rollers 18, 19 run on the same (single) contour, for example on the front side; it is also possible to provide a separate contour on the camshaft 15 for each of the control rollers 18 and 19; the movement of the 15 control rollers 18, 19 running on the camshaft is transmitted by rings 20, 21 on the movable socket of the vacuum switch tubes 16 and 17 respectively.Other It is also possible to have more than one such camshaft, for example each vacuum tube can have its own camshaft for operation. It is also possible to provide for switching elements, such as mechanical contacts, instead of vacuum switches. The transmission 13 described makes it possible to provide a first specific speed of the thread spindle 5 for operation of the switch W and thus the switch contacts 9, 10 from one operating position to the next operating position by moving the switch unit 7 and to provide a second specific speed per load shift for the camshaft 15 in a simple way.The geometric dimensions of the fixed switch 3, the movable switch 9, 10 of the switch W and the cam disc 15 of the LU load switch shall be such that, without a gear interface, the threaded spindle 5 rotated by the drive motor 2 directly operates the said components without translation. The electrical connection of each of the (jointly) movable switch contacts 9 or 10 to each of the two contact and guide rails 11 and 12 is made by an electrical line 22, 23 respectively. The electrical connection from these two contact and guide rails 11 and 12 to the vacuum switch tubes 16, 17 is made by further electrical lines 24, 25.17 to the unshown load line, other electrical lines 26, 27.

The operation of the load switcher according to the invention is as follows: It has already been shown above that both the contacting of the same fixed voting contacts 5 by both mobile voting contacts 9, 10 and the bridging of two adjacent fixed voting contacts 5 by one of the mobile voting contacts 9 or 10 are permissible stationary positions. In the example shown in Figure 1, the switch W has six fixed switch contacts 3, giving a total of 11 steady states, i.e. 11 different voltages that can be adjusted. At the start of a load change, the drive motor 2 is charged electrically; the threaded spindle 5 rotates, thus shifting, depending on the direction of rotation of the threaded spindle 5,Err1:Expecting ',' delimiter: line 1 column 179 (char 178)10 to their new position. The switchover is complete and the propulsion engine 2 is stopped by means of appropriate control and/or braking equipment which is familiar to the professional and is not shown here.

The load level switch according to the invention is extremely simple and compact and operates without power storage. Because of its very compact design and its extremely low space requirements, it is advantageously possible to place the load switch in the interior of the step transformer in single-phase modules directly in the area of the respective winding, at its winding or at other suitable places within the oil tank of the transformer. Such arrangements have been proposed in principle in the DE 20 2010 011 521 U1, DE 20 2010 011 524 U1 and especially DE 20 2010 012 811 U1. Their technical implementation has so far failed due to the large space requirements of the known load switches with their usually circular bar arrangements or insulating cylinders, which fit only poorly to the geometric profile of the available space at the windings. The invention reveals a suitable load level switch for such innovative applications.

Claims (6)

1. On-load tap changer for uninterrupted switching over between different winding taps of a tapped transformer, consisting of a selector (W) and a load changeover switch (LU), wherein

   - the selector has fixed selector contacts (3), which are respectively electrically connected with the individual winding taps and which are arranged along a linear path,

   - the fixed selector contacts (3) are selectably connectible by two longitudinally displaceable, movable selector contacts (9, 10) of the selector (W),

   - switching elements (16, 17), particularly vacuum interrupters, are arranged in the load changeover switch (LU) for uninterrupted switching over for each phase,

   - a motor drive with a drive motor (2) is arranged for initiation of a switching over process of the on-load tap changer,

   characterised in that

   - the two movable selector contacts (9, 10) and the switching means (16, 17) are so directly actuable by means of the drive motor (2) that the initiation of the drive movement of the drive motor (2) at the movable selector contacts (9, 10) and the switching means (16, 17) takes place without interposition of a mechanical energy store,

   - a rotational movement produced by the drive motor (2) of the motor drive is directly transmissible to a threaded spindle (5),

   - not only the movable selector contacts (9, 10), but also the switching means (16, 17) are actuable by the rotating threaded spindle (5),

   - a spindle nut (6) is guided on the threaded spindle (5) to be displaceable in the direction of the linear path,

   - the spindle nut (6) carries a selector contact unit (7), on which the movable selector contacts (9, 10) are fastened firmly and fixed in their spacing from one another and are actuable in common with the selector contact unit (7);

   wherein

   - the on-load tap changer is arranged on a support plate (1),

   - contact and guide rails (11 and 12) of electrically conductive material are disposed on the support plate (1) parallel to one another and not only parallel to the path of the fixed selector contacts (3), but also parallel to the threaded spindle (5) longitudinally of the path, which rails on the one hand ensure mechanical guidance of the selector contact unit (7) and on the other hand serve for electrical connection of the movable contacts (9, 10) with respect to the switching elements (16, 17).
2. On-load tap changer according to the preceding claim, wherein

   - the spacing between the two parallel movable selector contacts (9, 10) and the length of the fixed selector contacts (3) are so dimensioned that not only a connection of two adjacent fixed selector contacts (bridging connection) by a respective one of the movable selector contacts (9 and 10), but also a resting in common of two movable selector contacts (9 and 10) on one of the fixed selector contacts (3) are possible.
3. On-load tap changer according to claim 1, wherein

   - the switching elements are vacuum interrupters (16, 17),

   - the actuation thereof is effected by cam rollers (18, 19), which co-operate with at least one contour of at least one cam disc (15), and

   - the at least one cam disc (15) is mechanically connected with the threaded spindle (5).
4. On-load tap changer according to the preceding claim, wherein

   - the at least one cam disc (15) is mechanically connected with the threaded spindle (5) by way of an intermediate transmission (13).
5. On-load tap changer according to any one of the preceding claims, wherein

   - the electrical connection of each one of the selector contacts (9 or 10), which are movable in common, with a respective one of the two contact and guide rails (11 and 12) is effected by a respective electrical line (22, 23),

   - the electrical connection of these two contact and guide rails (11 or 12) with respect to the vacuum interrupters (16, 17) is effected by further electrical lines (24, 25), and

   - finally the electrical connection of the other side of the vacuum interrupters (16, 17) with respect to a load diverter is effected by yet further electrical lines (26, 27).
6. On-load tap changer according to any one of the preceding claims, wherein

   - the on-load tap changer is arranged in the interior of the tapped transformer in single-phase modules directly in the region of the respective winding, at the core thereof or at other suitable places within the oil vessel of a transformer.