|Title of Invention||
|Abstract||The invention relates to a selector switch for tapped transformers to enable continuous tap switching with respect to a tapped winding, whereby fixed stepped contacts are arranged inside a cylinder made of insulating material on a horizontal plane for each phase. A rotating actuating shaft is located inside the insulating cylinder. The actuating shaft has a moveable hinged contact carrier for each phase that is to be switched and vacuum switching cells are respectively and vertically arranged on said contact carrier.|
|Full Text||Selector switch
The invention relates to a selector switch for tapped transformers according to the
classifying clause of the first patent claim.
Such selector switches are already known from DE 38 33 126 C2.
Selector switches serve at transformers for switching over the taps of the regulating windings of these transformers under load and thereby to compensate for voltage changes in desired manner.
Selector switches can be manufactured and used less expensively because of dispensing with the otherwise usual separation of selector and load change-over switch. During the switching-over operation, arcs appear at different contacts in the selector switch. In order to avoid this, a selector switch has been proposed in the afore-mentioned DE 38 33 126 C2, in which two movable mechanical switching contacts, which are pivotable together at the same time, are provided on a common contact carrier in each phase to be switched and wherein a respective vacuum switch cell, which is similarly arranged on the contact carrier, is provided in series with each of the two movable mechanical switching contacts. The fixed tap contacts of the selector switch, which can be switched to by the pivotable mechanical switching contacts, are arranged on a concentric circle in the wall of a cylinder of insulating material.
The vacuum switch cells are arranged to lie horizontally on the contact carrier and are controlled or actuated by a cam track which is arranged on a further concentric circle and axially between the circle of the fixed tap contacts and an additional wiper ring.
These known selector switches have several disadvantages.
On the one hand, due to the arrangement of the vacuum switch cells lying horizontally on
the common contact carrier, an undesirably large diameter of the cylinder of insulating
material and thereby of the selector switch result.
Vacuum switch cells have certain minimum dimensions in dependence on their switching
power, particularly an appreciable longitudinal extent. Moreover, the actuating plungers
protrude in longitudinal direction out of the vacuum switch cells. It is therefore obvious that
the common contact carrier must have a radial extent which is dictated by the dimensions
of the vacuum switch cell and the actuating means and which altogether fixes the diameter
of the selector switch.
Apart from these general problems of dimension, a particular disadvantage exists in the
case of horizontal installation of the vacuum switch cells according to the state of the art in
that, when the selector switch is filled with oil, air remains at the upper folds of the vacuum
cell bellows and is not completely displaced by the oil filling. This leads to an unequal
loading of the corresponding vacuum cell bellows on actuation of the vacuum switch cell,
whereby there is the danger that this tears.
Such a remainder of residual air in the region of the vacuum cell bellows can be reliably
excluded in the case of the horizontal arrangement only by filling of the selector switch
under vacuum; such a vacuum filling is not, however, realisable, or realisable only with
unacceptably high effort, in situ, for example after modifications have been carried out.
Moreover, it is to be taken into consideration that selector switches altogether usually have
a large axial longitudinal dimension, i.e. an appreciable overall height. The fixed tap
contacts of the individual phases to be switched are arranged circularly one above the
other; the means - in the head of the selector switch - for actuation of the rotatable
switching shaft in the interior of the selector switch, which shaft carries the contact carriers
of each phase, as well as the means - in the base of the selector switch - for mounting this
switching shaft similarly require space, so that altogether, as explained, the selector switch
has an appreciable longitudinal dimension. This has the consequence that equally the
mentioned switching shaft in its interior is quite long.
Such switching shafts are usually made of glass-fibre-reinforced plastic or other insulating
material; however, metallic switching shafts have also been proposed.
The contact carriers in the known selector switch are fastened to the switching shaft by
means of fastening screws.
Further fixed fastening of a contact carrier to the switching shaft by means of a clamping
flange has been described in DE 44 14 941 C1.
Due to tolerances, different thermal expansions of oil vessel and switching column and
bendings inter alia, there can be problems, in the case of the known selector switches, for
the co-operation of the components arranged on the individual contact carriers - especially
the vacuum switch cells - with the actuating means arranged in a circle, particularly
because the actuating plungers of vacuum switch cells usually have only a relatively small
It is the object of the invention to eliminate these disadvantages and indicate a selector switch according to the category, which permits a space-saving arrangement of the vacuum switch cells and secure and reliable actuation thereof under all operating conditions.
This object is met by a selector switch with the features of the first patent claim. The subclaims concern particularly advantageous developments of the invention.
In the case of the selector switch according to the invention, the vacuum switch cells are
arranged to be perpendicular to the contact carriers. The contact carriers have wiper
contacts and are precisely guided by rollers in an output ring. The vacuum switch tubes
are controlled by cams in this output ring.
Blade wiper contacts, which are mounted in the contact carrier, conduct the current away
by way of the output ring.
Further blade wiper contacts at the contact carrier make the current feed possible.
According to a further feature of the invention, the contact carriers are each movably
arranged at the switching shaft.
The particular advantage of the selector switch according to the invention consists in the
fact that, apart from the smaller dimensions, all forces for the actuation of the vacuum
switch cells as well as the contact forces are axially supported at the stable oil vessel by
way of the output ring and the fixed contacts. Thereby, a radial loading of the switching
column, particularly sagging thereof, and resulting therefrom a variation of the control
times of the vacuum switch cells and a reduction in the contact forces are avoided.
Due to the contact carrier which is mounted to be rotatable or axially displaceable and
which is guided axially through the output ring, the switch sequence is ensured even in the
case of height displacements due to tolerances and different thermal expansion of oil
vessel and switching column.
The invention will be explained in more detail by way of example in the following by reference to drawings. The figures show:
Fig. 1 a first embodiment of a selector switch according to the invention in partial
lateral sectional illustration,
Fig. 2 a part of the contact carrier of this selector switch in sectional illustration
Fig. 3 a second embodiment of a selector switch according to the invention in
partial lateral sectional illustration,
Fig. 4 a schematic illustration of the circuit forming the basis of the selector switch
according to the invention,
Fig. 5 a modified such circuit and
Fig. 6 a typical switching sequence of a selector switch according to the invention.
The selector switch illustrated in Figure 1 shows an embodiment of the invention with a
contact carrier 3 rotatably mounted at a switching shaft 2 and vacuum switch cells 27 and
28 arranged perpendicularly to this.
With regard to the constructional format in detail:
The selector switch consists of an insulating material cylinder 1, in which a switching shaft
2, preferably of insulating material, is arranged centrally and to extend longitudinally
through the insulating material cylinder 1. The switching shaft 2 is rotatable in known
manner; Geneva wheels, which are not illustrated, usually serve for this purpose.
Similarly, the mounting of the switching shaft 2 at the base of the insulating material
cylinder 1 is not illustrated.
The switching shaft 2 carries a contact carrier 3, which is mounted to be rotatable in a
bearing block 4 on the switching shaft 2, in each plane of the fixed tap contacts 16, which
are to be actuated and are explained more closely further below. The bearing block 4 is
fastened to the switching shaft 2 by screws 4.1 and 4.2.
The contact carrier 3 consists of a bearing part 5, a carrier housing 6 and the contact
housing 7. The individual components of the contact carrier 3 are connected together by
screws 8 and 9. The contact housing 7 in turn consists, in the illustrated embodiment, of
an upper contact housing part 10 and a lower contact housing part 11; the two parts are
again connected together by further screws 12. The contact housing 7 can equally well be
formed in one piece. The bearing part 5 has a bearing point 13, in which is guided a pin
14 which produces the connection to the bearing block 4 and thereby permits the rotational
movement. The pin 14 is secured in position by a cross-pin 15.
Altogether, the entire contact carrier 3 is thereby pivotable as complete assembly about the pin 14 and thereby relative to the stationary switching shaft 2.
Fixed tap contacts 16, which are electrically connected with the taps of the regulating winding of the tapped transformer to be switched, are arranged in the wall of the insulating material cylinder 1, each time in a separate plane for each phase to be switched. Connection to the fixed tap contacts 16 can be made through corresponding contacts 17 and 18. These contacts 17 and 18 are arranged beside each other in horizontal direction on the contact carrier in such a manner that, on pivotation of the switching shaft and thereby of the contact carrier 3, one of the contacts 17 and 18 each time reaches the adjacent new fixed tap contact 16 before the other of these contacts leaves the previous fixed tap contact. One contact 17 thus acts as switching contact and the other contact 18 acts as auxiliary contact.
In Figure 2, there is shown the arrangement of the two contacts 17 and 18 from above, with one beside the other on the contact carrier 3, and the co-operation with the respective fixed tap contact 16. In the embodiment illustrated in Figure 2, the contact 17 acting as switching contact is doubled for the sake of a highest possible current-carrying capacity, i.e. constructed to consist of two parts 17a and 17b electrically connected together. Each of the contacts 17 and 18 consists of a respective upper contact part 17.1 or 18.1 and a respective lower contact part 17.2 or 18.2. In the special construction of the switching contact illustrated in Figure 2, the contact 17 there consists of, in total four parts, namely two upper contact parts 17.1a and 17.1b and two lower contact parts 17.2a and 17.2b. This double construction of the contact 17 acting as switching contact is rational for various embodiments although not essential for the invention. The upper contact parts 17.1 and 18.1 and also the lower contact parts 17.2 and 18.2 of each of the two contacts 17 and 18 are mounted to be rotatable about separate centres of rotation 19, 20, 21 and 22 at the contact housing 7. They are urged towards each other by springs 23, 24, 25 and 26 in the direction of the fixed tap contact 16 disposed between them in the connected state.
In other words, the respective upper contact part 17.1 or 18.1 and the corresponding respective other contact part 17.2 or 18.2 press with defined contact force from both sides onto the respectively connected fixed tap contact 16. Due to the described mounting about these separate centres of rotation 19, 20, 21 and 22, a running-up onto the fixed tap contacts 16 is possible. In Figures 1 and 2, only the contact parts, centres of rotation and springs lying at the front or at the top in direction of view can be seen.
Furthermore, two vacuum switch cells 27 and 28 are fastened on each contact carrier 3 in each case by means of upper and lower fastening clamps 29, 30, 31 and 32 in such a manner that the bellows 33 and 34 and the actuating plungers 35 and 36 of the vacuum switch cells 27 and 28 extend upwardly. Of the just described components too, only that lying at the front in direction of view can be seen in the Figure 1. Two levers 37 and 38, which are each equipped at a free end with a roller pin 41 or 42 with a control roller 39 or 40, serve for actuation of the actuating plungers 35 and 36 of the vacuum switch cells 27 and 28. At their respective other free end, they act on the above-described actuating plungers 35 and 36. The two levers 37 and 38 are mounted to be rotatable about centres of rotation 43 and 44; it is also possible to provide a common centre of rotation. The control rollers 39 and 40 of the two levers 37 and 38 in turn correspond with a control ring 45, which has an upper control profile 46 and a lower control profile 47. The control ring 45 extends radially at the inward wall surface of the insulating material cylinder 1. It is evident from Figure 1 that the first control roller 39 corresponds with the lower control profile 47, i.e. runs along on it and, in the same manner, the second control roller 40 runs along on the upper control cam 46. The two control cams 46 and 47 thus serve for actuation of the vacuum switch contacts 27 and 28 in that, when the corresponding control roller 39 or 40 runs up onto a cam, the associated lever 37 or 38 is pivoted about its fulcrum 43 or 44 and thereby actuates the corresponding actuating plunger 35 or 36 of the vacuum switch cell 27 or 28.
Moreover, an output contact ring 48, which comprises a connecting element 49 leading outwards and serves for load output, is disposed at the inward side of the insulating material cylinder 1. The control ring 45 and the output contact ring 48 can be united into a single component of conductive material in particularly simple manner, as is shown in Figure 1. The output contact ring 48 in turn again corresponds with a mechanical output contact 50, which is arranged on the contact carrier 3 and, similarly to the contacts 17 and 18 described further above, again consists of an upper output contact part 50.1 and a lower contact part 50.2. These two output contact parts 50.1 and 50.2 are analogously mounted to be rotatable separately about further centres of rotation 53 and 54 and are urged towards each other by further springs 51 and 52 in such a manner that they engage around the output contact ring 48 with defined contact pressure.
Finally, the contact carrier 3 has two rollers 55 and 56 which roll along on the output contact ring 48 on both sides and thereby guide the entire contact carrier 3. It is possible by the described arrangement to compensate for tolerances of any kind and in particular also to compensate for sagging of the long switching shaft. The contact carriers 3
arranged to be pivotable about the switching shaft 2 are in every case guided in defined manner by the output contact ring 48 so that, in spite of the described tolerances, a precise control of the control rollers 39 and 40 and thereby actuation of the vacuum switch cells 27 and 28 is given notwithstanding their only small actuating travels.
A further embodiment of a selector switch according to the invention is illustrated in Figure 3. In this case and in departure from the previously explained example, the contact carrier 103 is arranged not to be rotatable, but displaceable longitudinally. Again, a switching shaft 102, which carries a longitudinally displaceable contact carrier 103, is disposed, centrally arranged, within an insulating material cylinder 101. The longitudinal displaceability is realised by means of a guide 104. In this case, too, two vacuum switch cells, of which only the front vacuum switch cell 105 is illustrated, are arranged perpendicularly. In each plane, fixed tap contacts 106 are again disposed circularly in the wall of the insulating material cylinder 101 and, again, connection to these is made by a switching contact as well as an auxiliary contact, of which only an upper contact part 107.1 and in an associated lower contact part 107.2 are illustrated in the Figure. In similar manner, an output contact ring 108 is again disposed in the interior of the insulating material cylinder 101 and is surrounded by an output contact which again consists of an upper output contact part 109.1 and a lower output contact part 109.2. The guidance of the complete contact carrier takes place in this case by a roller 110, which runs in the profile of the output contact ring 108. The control of the vacuum switch cells again takes place by two levers 115 and 116, which at their free ends have respective control rollers 113 and 114, which in turn run along on a lower control profile 111 or an upper control profile 112 and in that manner actuate the actuating plungers of the vacuum switch cells, of which only the actuating plunger 117 of the vacuum switch cell 105 forward in direction of view is illustrated.
A circuit, which is realised by the selector switch according to the invention, is illustrated in schematic manner in Figure 4. The electrical connections between the contacts 17 and 18 to the vacuum switch cells 27 and 28 and from there in turn to the output contact 50 and thereby to the output contact ring 48 are not illustrated in Figure 1, which corresponds with this illustration.
A circuit, in which - as shown in Figure 2 - the switching contact 17 consists of two contact parts 17a and 17b arranged beside each other, is illustrated in Figure 5. The electrical
connections are only schematically indicated also in this illustration, which corresponds with Figure 2. It is evident that the basic manner of function does not differ, i.e. the same switching sequence is attainable by the circuit according to Figure 4 as well as also that according to Figure 5.
Such a switching sequence, obtainable by way of example, is illustrated in Figure 6.
In that case, a selector switch is illustrated with different switching steps. Such a selector switch with different switching steps is, in principle, already known from EP 0 160 125. In that case, the centre-to-centre spacing between the fixed tap contact lying at the main winding and the two fixed tap contacts adjacent thereto is greater than the centre-to-centre spacing between the remaining fixed tap contacts. This enables use of the selector switch even in transformers with higher nominal voltage; a higher standing surge voltage can thereby be achieved. Fixed tap contacts, which are constructed differently and suitable for such a selector switch, are also disclosed in this specification.
Independently thereof, it is particularly advantageous to make the fixed tap contacts 16 not curved as is usual according to the state of the art, i.e. parallel to the curve of the insulating cylinder 1, but straight, as is indicated in Figure 2. Whilst the respective upper or lower contact parts 17.1 and 18.1 constantly run along the same path of the fixed tap contacts 16 according to the state of the art, it is achieved by the straight construction that other points of the surface of the fixed tap contact 16 are wiped constantly, which reduces their wear.
1. Selector switch for tapped transformers for uninterrupted switching-over between taps of a regulating winding of a tapped transformer, wherein the selector switch comprises a cylinder of insulating material as housing, wherein fixed tap contacts, which are in electrical connection with the taps, are arranged in the interior of the cylinder of insulating material in a,circle)in an horizontal plane for each phase, wherein a rotatable switching shaft, which comprises a similarly rotatable contact carrier for each horizontal plane of fixed tap contacts, is disposed in the centre of the cylinder of insulating material, wherein each of the contact carriers comprises at least two mechanical contacts which can each be brought into contact with the fixed tap contacts of the respective horizontal plane, wherein at least one of the contacts on each contact carrier is electrically connected with a first vacuum switch cell and at least a one of the contacts on each contact carrier is electrically connected by way of an interposed circulating current-limiting resistor with a second vacuum switch, and wherein the respective other side of the two vacuum switch cells on each contact carrier is electrically connected with a respective load output line, characterised in that all contact carriers (3) are pivotably connected to the switching shaft (2) to be movable independently of each other and that the two vacuum switch cells (27, 28) are arranged on the respective contact carrier (3) to be perpendicular thereto in such a manner that the actuating plungers (35, 36) thereof extend in substantially axial direction.
2. Selector switch according to claim 1, wherein each of the contact carriers (3) is pivotably connected to the switching shaft (2) to be rotatable about a fulcrum.
3. Selector switch according to claim 1, wherein each of the contact carriers (103) is
pivotably connected to the switching shaft (102) to be longitudinally displaceable
4. Selector switch according to one of claims 1 or 2, wherein each of the contacts (17, 18) consists of at least one upper contact part (17.1, 18.1) and at least one lower contact part (17.2,18.2), wherein each contact part (17.1,18.1; 17.2, 18.2) is pressed against the other against the force of at least one spring (23, 24, 25, 26) in such a manner that, on the switching to a fixed tap contact (16), this is mechanically enclosed at both sides and made contact with electrically.
5. Selector switch according to one of claims 1 to 4, wherein the fixed tap " contacts (16) in the interior of the cylinder (1) of insulating material have an horizontal dimension which is not matched to the internal outline of the cylinder (1) of insulating material, but extends, in particular, rectilinearly.
6. Selector switch according to one of claims 1, 2, 4 or 5, wherein a control ring (45), which has an upper control profile (46) as well as a lower control profile (47), is arranged at the inward wall surface of the cylinder (1) of insulating material for each phase to be switched and thereby for each horizontal plane of fixed tap contacts (16), that a lever (37, 38) mounted to be rotatable about a fulcrum (43, 44) is arranged on each contact carrier (3) for each of the two vacuum switch cells (27, 28) and that each lever (37, 38) acts by a respective one of its two free ends on an actuating plunger (35,
36) of a vacuum switch cell (27, 28) and by its respective other free end on a respective one of the control outlines (46,47) in such a manner that the respective vacuum switch cell (27, 28) is actuable in dependence on the three-dimensional shape of the respective control outline (46,47).
7. Selector switch according to one of claims 1, 2 or 4 to 6, wherein each load
output line consists of a concentric output contact ring (48), which is arranged at the
inward wall surface of the cylinder (1) of insulating material and comprises a
connecting element (49) led outwards and which is contactable by an output contact
(50) which is arranged on the respective contact carrier (3) and is electrically
connected with the respective vacuum switch cells (27, 28) on this contact carrier (3).
8. Selector switch according to one of claims 1, 2 or 4 to 7, wherein each of the
contact carriers (3) comprises two rollers (55, 56), which roll along on both sides of
the corresponding output contact ring (48) in such a manner that the respective contact
carrier (3) is guided in constrained manner.
9. Selector switch according to one of claims 1, 2 or 4 to 8 wherein control ring
(45) and the output contact ring (48) of each phase are united each time into a single
|Indian Patent Application Number||IN/PCT/2000/251/CHE|
|PG Journal Number||13/2008|
|Date of Filing||07-Aug-2000|
|Name of Patentee||MASCHINENFABRIK REINHAUSEN GMBH|
|Applicant Address||Falkensteinstrasse 8, D-93059 Regensburg,|
|PCT International Classification Number||H01H 9/00|
|PCT International Application Number||PCT/EP1999/002020|
|PCT International Filing date||1999-03-25|