EP2845212A1 - Selector for a tap changer - Google Patents

Abstract

The invention relates to a selector for a tap changer for switching among winding taps of a step transformer without interruption, wherein the selector consists of a plurality of honeycomb segments arranged horizontally one over the other and vertically next to each other, which honeycomb segments can be fixed to each other by contact holders and pins. According to the invention, by means of such a modular design, a large variety of selector variants is possible using only few components.

Description

 Selector for a tap changer

The invention relates to a selector for a tap changer for uninterrupted switching between winding taps of a tapped transformer.

Tap changers have been known in many technology for many years

Designs. They regularly have a selector and a diverter switch.

The selector is used for the powerless preselection of the new winding tap to be switched to below.

The diverter switch is used for the actual - fast - uninterrupted switching from the previous to the new, no-load preselected winding tap. A step switch with a selector is known from the company publication "OILTAP® M" of the applicant, Druckimpressum 03/09 In this selector, fixed selector contacts are arranged in a circle in several horizontal planes on an insulating material stand These fixed selector contacts are located in the interior of the insulating material stand The fixed selector contacts, which are each in electrical connection with a winding tap of the associated tapped transformer, which is to be regulated, are here so on vertical

Isolierstoffstäben arranged and fastened. These Isolierstoffstäbe may consist of kraft paper, fiberglass or other insulating material. The Isolierstoffstäbe form a framework of vertical, mutually parallel rods; The framework is fixed by an upper and a lower ring.

From the company publication "VACUTAF" ® W - on-load tap-changer for control transformers ", Druckimpressum 05/06 of the applicant, a further tap-changer is known. In the selector shown there, the fixed selector contacts are again arranged in a circle in several horizontal planes and can be connected by a central drive shaft with movable selector contacts, but the arrangement of the fixed selector contacts is provided there in the wall of a closed insulating cylinder. Such a

Insulating cylinder, in turn, may consist of kraft paper, fiberglass or other insulating material. From the further company publication "VACUTAP® - On-load tap-changer for furnace applications", Druckimpressum 09/07 of the applicant, a tap-changer of the type VR® is known, in which the selector does not consist of a closed insulating cylinder but of several individual cylindrical shells Segments that in the assembled state de facto a cylinder contour with

form corresponding spaces.

From DE 10 2010 007 535 A1 a tap-changer with freewheeling element is known. The tap changer has a switching shaft on which a plurality of actuating elements arranged parallel to one another are fastened. The actuators are designed as cams with projections. Parallel to the switching shaft mechanical switching elements are arranged, which are actuated via the projections of the cams. The mechanical switching elements are connected between the selector and the vacuum interrupters of the diverter switch. By operating the mechanical switching elements, the vacuum interrupters are to be protected in the non-load current leading load branch from possibly occurring surge voltages.

From DE 10 2010 020 137 A1 a switching arrangement for a diverter is known. This diverter, the voltage or currentless switching between

Winding taps is used, has two integrally formed, arranged in two levels one above the other fixing elements. In addition, the fixing elements in the outer ring portion openings for the passage of contact bars. Furthermore, each fixing element has a sleeve portion arranged in the middle, in which a switching shaft is mounted. By way of a contact arrangement which is fastened to the selector shaft, in each case two contact rods are connected to one another in an electrically conductive manner and thus certain winding taps are selected.

From US 3,798,395 A a tap changer for transformers is known, which consists of a selector and a load switch. The selector is used for the power-less preselection of tap tap and the load switch for fast switching under voltage. The selector includes two rotary contacts which connect the taps of the transformer with one slip ring each and are driven by a shaft. From EP1 105896B1 a tap changer with a preselection for uninterrupted switching between different winding taps of a tapped transformer is known. Selection in general can on the one hand be designed as a coarse-step selector, on the other hand as a turner. In both cases, these means expand the control range. In other words, existing selector contacts can be used multiple times. The coarse-grained selector does this by switching part of the trunk winding on or off. By the turner it is possible to add the control windings to the main winding or to switch against them, so to subtract. Also one

Combination of coarse selector and inverter is possible. Once a selection is used, the actual selector is called a fine selector. In all three cases the

 Selection arranged constructively next to the actual fine selector (selector). Again, the structural implementation is carried out by means of cylinder segments or a framework of Isolierstoffstäben to which the movable and fixed preselector contacts are attached. The prior art in such selectors for tap changers can therefore be summarized as follows: The individual fixed selector contacts are arranged in a plurality of horizontal planes circular around a rotatable drive shaft around. The arrangement of the selector contacts and their fixation is carried out either on individual rods of insulating material forming a cage stand, or in the wall of a Isolierstoffzylinders, or even in the wall of individual Isolierstoffzylindersegmenten, which also put together a circular arrangement.

As explained, the positioning of the fixed selector contacts is carried out vertically one above the other - in a Isolierstoffgerüst along the rods as support elements - in several levels.

Different divisions of tap changer, d. H. the number of possible too

connecting winding taps and thus number of fixed selector contacts, are due to the different number of individual Isolierstoffstäbe, the diameter of the

Isolierstoffzylinders or realized the different number of horizontal planes. The expansion of the control range is done via preselector which are designed as a coarse selector, Wender or a combination of both. These parts also consist of Isolierstoffzylindersegmenten or Isolierstoffstäben which are arranged next to the fine selector. The prior art has various disadvantages overall. The main drawback is that for different numbers of connectable winding taps of the associated tapped transformer and thus different numbers solid

Voter contacts also different constructive configurations of the voter are required.

For reasons to be met electrical voltage resistance, the individual fixed selector contacts must have a certain minimum distance both horizontally and vertically to each other. A large number of fixed wählerkontakte in a horizontal plane thus inevitably leads to a large diameter of both the Isolierstoffgerüstes and the insulating cylinder. Similarly, a large number of individual horizontal planes arranged one below the other results in an increased length of insulating framework as well as insulating cylinders. Upon extension of the selector (selector) by a selection, e.g. one

 Wenders, the diameter of the entire assembly is greatly increased. It is also not possible to position these preselections below the fine selector in order to meaningfully use any available space. So it must be maintained in a variety of sizes in a manufacturer of tap changers both Isolierstoffstäbe and the respective fixing rings and different insulating cylinder; the use of common good is thus extremely limited. Overall, this complexity leads to high costs. In addition, in the manufacture of tap changers can not be freely selected, whether a selection in the form of a coarse selector or a Wenders next to or below the fine selector (selector) is arranged.

The object of the invention is to eliminate these disadvantages and to provide a selector with an optional selection, which is modular and a reduction in complexity while covering the same variance, d. H. Bandwidth of possible numbers of connectable winding taps allowed.

This object is achieved by a voter with the features of the first claim. The subclaims relate to advantageous developments of the invention. The invention is based on the general idea, a generic voters of the modular form from always uniform, mutually offset next to each other and arranged honeycomb segments, is constructed. According to the invention, the essential components for such a selector are honeycomb segments which are connected to one another via contacts, contact holders and bolts and are thereby surrounded by a shield.

The selector according to the invention offers numerous advantages. First of all, only a few different equal parts are required for its production. With these can be realized by the construction by means of the honeycomb segments with the same diameter different lengths and heights of the voter. In other words, the voter according to the invention is adaptable with low complexity to widely varying numbers of winding taps to be controlled and thus required fixed voter contacts.

Another advantage of the invention is that gaps remain in each horizontal plane between the connecting regions of the honeycomb segments and the contacts arranged there. Since the voters according to the invention, as usual, flows around and flows through the insulating oil in the transformer boiler, oil lines are thus realized both horizontally and vertically between all fixed selector contacts; this optimization of

 Insulation distances leads to a high dielectric strength in a compact design.

The honeycomb segments also make it possible to arrange selection in the simplest manner either next to or below the fine selector and to connect them together. This allows more flexible response to given space. In addition, the same parts can be used.

Due to the offset levels of the selector contacts, the fine selector can be halved in height compared to the prior art. Due to the honeycomb structure there are no direct rod sections between the planes, whereby the dielectric strength is increased.

The invention will be explained in more detail below with reference to drawings.

Show it: 1 shows a honeycomb segment according to the invention

Figure 2 shows an inventive honeycomb segment with contacts, contact holders and

 bolt

 Figure 3 five interconnected honeycomb segments

Figure 4 shows a contact with contact shield

Figure 5 shows an inventive selector

Figure 6 shows an inventive selector with mutually arranged fine selector and preselector

 7 shows a erfmdungsgemäßer voters with juxtaposed fine selector and preselector

Figure 1 shows a honeycomb segment 1 according to the invention. This is preferably made of a thermoplastic having a high dielectric strength, e.g. PPA. The

Honeycomb segment 1 has four receiving areas 2 for contacts 3, contact holder 4 and pin 5. In this case, each receiving area 2 has at least one contact recess 3.1 for the contact 3, at least one contact holder recesses 4.1 for the contact holder 4 and at least one bore 5.1 for the bolt 5. In addition, the contact holder 4 also have holes 4.2, which with the holes 5.1 of the honeycomb segments. 1

correspond.

FIG. 2 shows a honeycomb segment 1 in which the contact holder 4 is arranged around the contacts 3 in the receiving areas 2. The contact holder 4 can be pushed onto the contacts 4. In addition, it is possible to connect the contact holder 4 directly to the contact 3 by means of injection molding. In order to ensure a tight fit, recesses, holes or other geometric structures on the contact can help to form a positive connection between contact 3 and contact holder 4 during encapsulation. Also, the contact holder 4 is preferably made of a

Thermoplastic with a high dielectric strength. The number and strength of

Contact holder 4 can be varied as needed.

Through the contact recesses 3.1 and the contact holder recesses 4.1, the contacts 3 and attached to these contact holder 4 can be positioned in the receiving areas 2. Figure 3 shows five interconnected honeycomb segments 1, which form a ring with three levels for possible contacts 3. The two upper contact levels are assigned to one phase and provide ten contacts 3 available. To increase the amount of the contacts 3 to 12 or 14, it requires only a slight change in the honeycomb segments 1. This makes it possible, with the same diameter of a selector 7 more honeycomb segments 1, ie at twelve contacts six honeycomb segments 1 and 14 contacts seven

Honeycomb segments 1, to connect with each other.

When connecting the honeycomb segments 1, the first contact 3 with the

Contact holders 4 inserted into the receiving areas 2. Then another

 Honeycomb segment 1, with an empty receiving area 2, in the contact with 3 and

Contact holders 4 fitted receiving area 2 of the first honeycomb segment 1 inserted. Since the bores 5.1 of both honeycomb segments 1 correspond to the bores 4.2 of the contact holders 4, all parts can be firmly connected to one another by means of the bolts 5. The bolts 5 are thereby led out and locked first through the holes 5.1 of the honeycomb segments 1, then through the contact holder 4 and finally through the holes 5.1 on the other side.

The use of a contact 3 or a contact holder 4 is not mandatory when assembling. Thus honeycomb segments 1 can be connected only with the aid of the bolt 5. This is advantageous when higher distances between the individual contacts 3 must be maintained at high voltages.

In addition, it can be seen in FIG. 3 that the individual contact planes are offset from each other. In this case, the dielectric distance of the individual contacts 3 is extended, although the height of the entire selector is reduced.

FIG. 4 illustrates a contact shield 6 with the aid of which the dielectric strength can be additionally increased. This contact shield is formed in two parts in this embodiment. During assembly, both parts are positioned one above the other and connected with the help of integrated snap hooks. Other joining methods are conceivable, i. glue, screw, etc.

FIG. 5 illustrates an inventive selector 7 in the mounted state. This is composed of a plurality of honeycomb segments 1, which at the receiving areas. 2 are composed. Clearly visible are the different levels of contact with the different contacts 3. With only a few parts can thus inventively and modular produce a complete selector 7. Inside the selector 7, a relay column 8 with diverting rings 9 as well as contact bridges with a drive train (not shown here) are shown. In the upper part of the selector 7, interconnected honeycomb segments 1 without contacts 3 can be seen.

In Figure 6, a selector 7 is shown, which is divided into fine selector 10 and preselector 1 1. As can be clearly seen, the fine selector 10 and the preselector 11 are made of identical honeycomb segments 1, which are connected to each other in the same way. An intermediate gear 12 separates the located inside the contact bridges and drive trains.

In Figure 7, a selector 7 is shown, in the fine selector 10 and 11 preselector

are arranged side by side. Again, uniform honeycomb segments 1 are always used for both units.

Overall, the invention offers numerous advantages: A voter can be built in almost any variety of variants from only a few different components. At the

Assembling a contact 3 is not necessary to connect the honeycomb segments 1 with each other. The honeycomb structure with its horizontal and vertical

Interspaces allow a particularly good circulation of the surrounding

Insulating medium, usually insulating oil. Due to the shape of the honeycomb, there are no direct rod sections, i. direct connections, as in the prior art, between the contact planes. A high dielectric strength is ensured, although the height of the fine selector is reduced.

When expanding the voter to a coarse-step selector or turner, identical honeycomb segments can always be used. Also the free choice of the arrangement of the

Preselection, namely below the fine selection or next to it, brings many advantages. By shifting the voter contact levels of a phase, the height of the

Reduction of the fine selector by half, wherein the dielectric strength remains. When arranging the preselector below the fine selector, this can be used together with the diverter switch in the transformer tank or lifted out of this. This is particularly advantageous during assembly and maintenance. When assembling, it is no longer necessary to first install the selector in the transformer tank and connect it to the diverter switch later. Both parts can be installed simultaneously.

Claims

claims

1. Selector for a tap changer for the uninterrupted switching between two winding taps of a tapped transformer,

 wherein fixed contacts are circular in several horizontal planes at one

 Selector housing are arranged and

 wherein inside the selector housing a centrally extending rotatable

 Drive shaft is arranged, which carries in each horizontal plane of the fixed contacts at least one movable contact to the wiring,

 characterized,

 that the selector housing consists of several honeycomb segments (1),

 the honeycomb segments (1) are arranged next to one another in a circle in a horizontal plane,

 that a plurality of honeycomb segments (1) arranged in a circle in a circle are arranged vertically one above the other,

 in that the honeycomb segments (1) have receiving regions (2) and can be connected to one another via these receiving regions (2) such that a positive connection between at least two receiving regions (2) of the individual honeycomb segments (1) is produced when connecting at least two honeycomb segments (1) ,

2. selector according to claim 1,

 characterized,

 in that the receiving areas (2) have at least one bore (5.1) and in that at least one bolt (5) is inserted for fixing through the bores (5.1) when connecting two honeycomb segments (1).

3. Voter according to claim 2,

 characterized,

 the receiving regions (2) have at least one contact holder recess (4.1),

in that optionally a contact holder (4) with at least one bore (4.2) through which the bolt (5) can be inserted is positioned in the contact holder recess (4.1) and that a fixed contact (3) can be arranged on the at least one contact holder (4) is.

4. Voter according to claim 1 to 3,

 characterized,

 the selector (7) comprises a fine selector (10) and a preselector (1 1).

5. Voter according to claim 4,

 characterized,

 that the fine selector (10) and the preselector (1 1) are arranged vertically one above the other or horizontally next to one another.

6. Voter according to claim 4 or 5,

 characterized,

 that the preselector (1 1) is designed as a turner or as a coarse stage selector.

7. Voter according to claim 4 to 6,

 characterized,

 in that the fine selector (10) and the preselector (11) are separated from one another in the interior by an intermediate gear (12).

8. Voter according to claim 1 to 7,

 characterized,

 in that the selector (7) comprises five, six or seven honeycomb segments (1) per phase.

9. selector according to claim 3 to 8,

 characterized,

 in that a contact shield (6) is arranged around the contacts (3).

10. Voter according to claim 1 to 9,

 characterized,

 in that the honeycomb segment (1) is made of a thermoplastic, e.g. PPA exists.