Title of Invention

TAP CHANGER

Abstract

The invention relates to a tap-changer for low power switching on a step transformer. Said tap-changer is closed on the top by a tap-changer head which comprises a head flange wherein a drive shaft, which is guided from the outside, is mounted. An upper gear step and a hand wheel drive can be mounted on said head flange by means of a compatible hand wheel drive flange without requiring additional components, in particular, a special tap-changer head.

Full Text

Tap changer The invention relates to a tap changer for power-free switching over between different winding taps of a tapped transformer for voltage setting. Such a tap changer is already known from the company publication of the applicant 'Umsteller DEETAP® U, Betriebsanleitung BA 249/02de\ printing 0204/200. This known tap changer operates according to the principle of the rotary tap changer. It comprises an insulating material housing at which fixed contacts are arranged circularly in each of several horizontal planes. A rotatable insulated switching shaft is disposed in the interior of this insulating material housing and carries in each horizontal plane at least one switching contact by which electrical connection can be made to the corresponding fixed contacts in different ways depending on the respective basic circuit, for example as a star-point tap changer, simple centre tap changer, double centre tap changer, series-parallel tap changer or star-delta tap changer. The adjusting of the tap changer from one operating setting to another, i.e. the switching over between different winding taps of the connected tapped transformer, is carried out by rotation of the insulated switching shaft when the transformer is switched off, i.e. in the current-free and voltage-free state. The rotation of the insulated switching shaft usually takes place on a stepped transmission, on which an electric motor drive or also a mechanical manual drive acts as shall be explained in more detail in the following. The upper closure of the known tap changer forms the tap changer head with the attached upper transmission stage and the Geneva transmission, which is disposed thereunder, for drive of the insulated switching shaft. A shaft emanating from the respective motor drive or manual drive is connected with an outer shaft coupling at the upper transmission stage; the rotational movement of the shaft is transmitted to the upper transmission stage by way of a worm gear on a drive shaft which is vertically mounted in the tap changer head and which in turn has a Geneva crank at its lower end. The Geneva crank engages in a Geneva wheel, which is fixedly arranged on the insulated switching shaft at the upper end. A tap changer switching, i.e. a rotation of the insulated switching shaft through a defined angle with respect to the respective adjacent fixed contact, thus corresponds with a defined number, which is dependent on type, of revolutions of the driving shaft of the motor drive or manual drive. Certain variants of the known tap changer have instead, as a special construction, a direct mechanical actuation possibility of the insulated switching shaft by a handwheel, which is connected therewith and arranged centrally on the tap changer head, or a hexagon in conjunction with a socket wrench. Due to the direct central connection a special tap changer head is required for these constructions. This leads to an undesired variant multiplication of necessary parts of an otherwise identical tap changer. It is accordingly the object of the invention to indicate a tap changer according to category which avoids these disadvantages and in which all described actuation possibilities of the insulated switching shaft can be realised by a single tap changer head. This object is fulfilled by a tap changer with the features of the first patent claim. The subclaims relate to particularly advantageous developments of the invention. The tap changer according to the invention has only a single tap changer head with a head flange, to which an upper gear stage for actuation by motor drive or manual drive or a handwheel drive flange for actuation by a handwheel or by means of a hexagon adapter can be selectably fastened. The drive shaft which, as described, carries the Geneva crank at its lower end is also identical for all forms of actuation. The invention shall be explained in more detail in the following by way of examples of embodiment, wherein: Fig. 1 shows a part of the tap changer head of a tap changer according to the invention with an upper transmission stage mounted on the head flange, Fig. 2 shows a handwheel drive with a handwheel drive flange which can be mounted instead of the upper transmission stage, Fig. 3 shows a hexagon drive with, again, a handwheel drive flange which can be mounted instead of the upper transmission stage and Fig. 4 shows a cross-section of the complete tap changer head of a tap changer according to the invention, here with mounted handwheel drive at the head flange. Initially, Figure 1 shall be explained. Here, a tap changer head 1 is shown which comprises a head flange 2 with several concentrically arranged threaded fastening bores 3. An upper transmission stage 4 is mounted on the head flange 2. This upper transmission stage 4 has, in a manner known per se, a worm wheel 5 disposed in connection with the shaft (not illustrated) emanating from the motor drive or manual drive. The wormwheel 5 acts on a gearwheel 6 fastened to the vertically extending drive shaft 7. The rotational securing is effected by a key-and-groove connection 8. The drive shaft 7 is mounted in the head flange 2. A Geneva crank 9 is fastened to the drive shaft 7 at the lower end; a further key-and-groove connection 10 serves for the rotational securing. The Geneva crank 9 acts on a Geneva wheel 11, which is fastened by its flange 12 to the upper part of the insulated switching shaft (not illustrated here). The upper transmission stage 4 is closed at the top by a cover 13. In the form of embodiment illustrated in this figure the drive of the tap changer thus takes place by way of a physically separately arranged motor drive or also a manual drive, wherein the rotational movement is transmitted by a corresponding shaft train to the worm wheel 5 of the upper transmission stage 4. The components of an alternatively usable handwheel drive are shown in Figure 2. Provided for this purpose is a handwheel drive flange 14 which is similarly fastenable to the head flange 2 - not shown here - and in which the drive shaft 7 is mounted. The handwheel drive flange 14 has an upper cover 15 through which the drive shaft 7 is led. A handwheel 16 is fastened to the drive shaft 7 at the upper end. The fastening is effected by a thread 17 at the end face of the drive shaft 7 and the handwheel 16 is fastened by means of a screw 18; here, too, a key-and-groove connection 19, which corresponds in its physical position with the key-and-groove connection 8 in Figure 1, is provided for the rotational securing. A safety lock 20 can be provided in order to prevent unauthorised adjustment. An alternatively usable hexagon drive is shown in Figure 3. It again has the handwheel drive flange 14 in which the drive shaft 7 is mounted. However, here instead of a handwheel a hexagon adapter 21 is fastened above the cover 15 again by means of a screw 22 in the thread 17 of the drive shaft 7. The entire tap changer head of a tap changer according to the invention, here with mounted handwheel drive, is shown again in Figure 4. It can be seen that the head flange 2 as also the entire tap changer head 1 are completely identical to the embodiment, which was explained in Figure 1, with upper transmission stage. Instead of the upper transmission stage the handwheel drive flange 14 is here mounted on the head flange 2. The handwheel 16 acts on the drive shaft 7 and on the Geneva crank 9 arranged at the lower end and this in turn on the Geneva wheel 11 and thereby the insulated switching shaft. In this illustration for the sake of completeness an additionally arranged, known switch monitoring device 23 is also indicated, but is of no relevance to the invention and accordingly is not explained in more detail. It can be seen that with the tap changer according to the invention, thus independently of whether the drive takes place by way of a motor drive or manual drive and a corresponding upper transmission stage or a handwheel drive or also a hexagon drive, the same transmission mechanism always carries out the rotational movement: from the drive shaft 7 by way of the Geneva crank 9 to the Geneva wheel 11 and from there to the insulated switching shaft. This has the consequence that for every form of actuation the same number of revolutions is required in order to execute an actuation of the tap changer. It can be seen that in the tap changer according to the invention the type multiplicity has been substantially reduced; the head flange 2 has the function of an adapter on which the upper transmission stage 4 or handwheel drive flange 14 can be selectably mounted without further different components being required apart from the handwheel 16 and hexagon adapter 21 themselves. Patent Claims 1. Tap changer for power-free switching over between different winding taps of a tapped transformer for voltage setting, wherein fixed contacts are circularly arranged in at least one horizontal plane at an insulating material housing, wherein a rotatable insulated switching shaft is disposed in the interior and carries in each horizontal plane at least one switching contact by which electrical connection can be made with the corresponding fixed contacts, wherein the tap changer is closed at the top by a tap changer head (1) having a Geneva transmission (9, 11) for drive of the insulated switching shaft, wherein the Geneva transmission (9, 11) is itself drivable by a drive shaft (7) which projects by its free end vertically upwardly out of the tap changer head (1) and is mounted in a head flange (2) which in turn has several threaded fastening bores (3), characterised in that an upper transmission stage (4) which is known per se or a handwheel drive is selectably fastenable on the head flange (2) at the threaded fastening bores (3), that the handwheel drive comprises a handwheel drive flange (14) which can be screw-connected on the head flange (2), that the handwheel drive flange (14) has an upper cover (14) through which the drive shaft (7) is led and that a handwheel (16) or a hexagon adapter (21) is fastened to the upper free end of the drive shaft (7). 2. Tap changer according to claim 1, characterised in that the handwheel (16) or hexagon adapter (21) is fastened by a screw (18, 22) screwed into a thread arranged at the drive shaft (7) at the end face.

Documents:

4317-CHENP-2007 AMENDED CLAIMS 12-11-2014.pdf

4317-CHENP-2007 AMENDED PAGES OF SPECIFICATION 12-11-2014.pdf

4317-CHENP-2007 ENGLISH TRANSLATION 12-11-2014.pdf

4317-CHENP-2007 FORM-1 12-11-2014.pdf

4317-CHENP-2007 FORM-3 12-11-2014.pdf

4317-CHENP-2007 POWER OF ATTORNEY 12-11-2014.pdf

4317-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 12-11-2014.pdf

4317-CHENP-2007 CORRESPONDENCE OTHERS 19-03-2014.pdf

4317-chenp-2007-abstract.pdf

4317-chenp-2007-claims.pdf

4317-chenp-2007-correspondnece-others.pdf

4317-chenp-2007-description(complete).pdf

4317-chenp-2007-drawings.pdf

4317-chenp-2007-form 1.pdf

4317-chenp-2007-form 3.pdf

4317-chenp-2007-form 5.pdf

4317-chenp-2007-pct.pdf

4317-CHENP-2007-Petition for filing particulars.pdf

4317-CHENP-2007-Petition for POR.pdf