JPS6039809A - Load tap selector of transformer - Google Patents

Abstract

1. A load selector for tapped transformers for changing over from one tapping to the next one, comprising fixed step contacts (2, 3) which are arranged in a circle and connected to the tappings and switching contacts (5, 6, 7) from three current branches on a common contact carrier (4) which contacts can be simultaneously swivelled along the arc of a circle, - wherein all switching contacts (5, 6, 7) in each case carry the potential of the same step contact (2, 3) in their rest position, - wherein during swivelling of the contact carrier (4), the central switching contact (5) is substantially only moved in the radial direction in relation to the contact carrier (4), - wherein during swivelling of the contact carrier (4) the two outer switching contacts (6, 7) are swivelled in relation to the contact carrier (4) on levers (14, 12) which are positioned on the contact carrier (4), and - wherein the movements of the switching contacts (5, 6, 7) in relation to the contact carrier (4) are controlled by the step contacts (2, 3) which simultaneously constitute cams, characterised in - that each of the two outer switching contacts (6, 7) is supported by the free end of an arm of a two-armed lever (14, 12), - that the ends of the other arms of said two-armed levers (14, 12) are mechanically coupled to one another (16, 17) in such a manner, - that in the rest position of the contact carrier (4), the two outer switching contacts (6, 7) are swivelled to the flanks of the respectively selected fixed step contact (2, 3) by means of spring force (18), and - that when one of the two outer switching contacts (6, 7) runs up on to a fixed step contact (2, 3) the lever arms supporting the outer switching contacts (6, 7) are swivelled in opposite directions against the spring force (18) and the lever arms (14, 12) supporting the outer switching contacts (6, 7) are thereby spread out from the central switching contact (5).

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention provides a tap contact arranged on a circumference and connected to a tap and a contact supporting arm that is provided on a common contact support arm and rotates simultaneously on an arc. It has a group of switching contacts for three current branches and is involved in switching from one tap to the adjacent tap J r) for switching and σ) for the load tap selector of the transformer.

[Prior art and its problems]

For such a load tap selector, all switching contacts lead in their rest position to the position of the respective identical tap contact, and upon rotation of the contact support arm, the central switching contact moves only approximately radially relative to
When the contact support arm rotates, the switching contacts on both rows are tilted relative to the contact support arm on levers that are pivotally supported by the contact support arm.
It is known from European Patent Application No. 20029467 that the movement of the switching contact group relative to the contact support arm IC is controlled by fixed tap contacts which simultaneously serve as cams.

Usually the outer switching contacts are each connected in series with one current limiting resistor. This results in a so-called flag cycle, which is particularly advantageous from the point of view of the switching capacity provided in each individual contact.

In the rest position of this known load tap selector, the operating current of the transformer flows from one fixed tap contact through the central main switching contact, while the two outer contacts serve as resistive contacts and tap selection. No current flows when the device is at rest position +6. In order to ensure uninterrupted switching, in the intermediate position the resistive contact rides on the fixed contact, which remains energized, faster than the main switching contact is removed from this fixed contact. The corresponding energized resistive contact must already be in contact with the second resistive contact and the next fixed contact before it is disconnected from the fixed contact that has been current until then.

In order to meet these conditions, the width of the stationary contacts must then be greater than half the spacing between the resistive contacts and the spacing of the contact rollers must be greater than the spacing between two adjacent stationary contacts. However, this condition results in the fact that the spatial insulation distance between each resistive contact and the respective adjacent stationary contact in the rest position is relatively small with respect to the center distance of two adjacent stationary contacts.

However, in order to accommodate operating voltages as high as possible, the greatest possible spatial insulation distance, that is, the greatest possible distance between the contact roller and the adjacent stationary contact which is not energized, is required.

In order to obtain good conditions, in the device according to the above-mentioned European patent application, the resistive contacts are configured to be tiltable, so that when the movable contact system moves to one side, it abuts the fixed contacts from the other side. The resistive contact is tilted away from the central switching contact when contacting the fixed contact. During switching of this known load tap selector, there is therefore a greater distance between the outwardly tilted resistance switching contact and the central main switching contact in the intermediate position than in the rest position. . If a given diameter is adopted for the contact system, this results in a spatial insulation distance in the rest position that is greater than λ obtained with a contact arrangement with non-tilting resistive contacts, but this resistive switching contact and main The insulation distance between the switching contacts needs to be as large as possible, and further improvements are desired.

[Purpose of the invention]

11. This invention is given as follows: 1. It is an object of the present invention to provide a contact device for a load tap selector, which makes it possible to further increase the insulation distance between the switching contact and an adjacent fixed contact at which the load current does not flow. shall be.

[Means for achieving the purpose]

This object is achieved according to the invention so that the switching contacts of each row are each supported by the free ends of one arm of one double-armed lever, and the switching contacts of each row are supported by the free ends of the other arms of these two-armed levers. are mechanically connected to each other, and the switching contacts on both rows are tilted by the spring force in the rest position of the contact support arm to near the side of the fixed tap contact selected at that time, and the switching contacts on both rows When it gets on the hard nl tap contact, both outside 1
This is achieved by tilting the lever arms supporting the switching contacts of 1111 in opposite directions against the spring force so that the lever arms supporting the switching contacts of both rows move away from the central switching contact. h'i, done.

[Embodiments of the invention]

O) Invention σ-) According to an advantageous embodiment, the distance between the switching contacts of both rows in mutually distant positions during the switching process is approximately 25 inches greater than in the rest position. The levers supporting the switching contacts on both rows are each designed to be tiltable about two axes arranged symmetrically with respect to the central switching contact.

In another embodiment of the present invention, the levers supporting the switching contacts of the two arms are mutually equal and form a fork with two arms, and are formed in the same shape or mutually symmetrical and axially The switching contacts themselves are connected to one another with play by means of connecting devices which are located one to the other, with the switching contacts themselves being formed as rollers.

In this case, the central switching contact is supported by a two-armed lever which can be tilted around an axis guiding one of the two double-armed levers and is supported via a spring that generates contact pressure. Supported by arms.

According to yet another advantageous embodiment of the invention,
The marks guiding each lever pass a fixed tap contact at a distance greater than the axis of the roller serving as the switching contact, and the surface of the fixed tab contact is aligned in the direction of the pivot axis of the contact support arm. It is designed to be convex.

[Embodiments of the invention]

Next, as an embodiment of the load tap selector based on the present invention, the present invention will be explained in detail with reference to FIGS. 1 to 7 showing the operation progress of the contact system and FIG. 8 showing a partial cross section.

On the circumference of the inner wall surface of the insulating cylinder 1, only a part of which is shown in cross-section, multi-contact tap contacts fixed at equal intervals are arranged, and two of the taps Only the contacts are shown in FIGS. 1 to 7. Tap contacts 2, 3 reach these contacts of the close tap winding of the transformer and are electrically coupled to the -j-lo tap.

Contact support arm 4 with 1111 switching contacts 5, 6, and z
is capable of rotation around the axis of the insulating node l. In the rest position of the contact support arm 4, the Leno pin contact 5 is in contact with one of the tap contacts MJ! are doing. 1/1j is in contact with the tap contact 2 in the position shown in FIG. 1, and is in contact with the tap contact 3 in the position shown in FIG. In this arrangement, the switching contacts 5, 6, 7 i:I are designed as rollers and are supported on iMb 8, 9, 1.0.

Ii'41 with switching contact 5 within rζ] 8 is a single arm lever]
This lever mouth member is supported by a double-arm lever 14 which supports the horizontal point 6 and is mounted on a shaft 15 fτJ.
I'm being kicked. The other bipedal lever 12 supports the switching contact 7 and is mounted on an axle 13. The waxes of the levers 14, 12 on the opposite side from the switching contacts 6.7 are optically coupled to each other so that these storms are respectively operated in opposite directions.

As a connection, a pin 16 that engages with play in the slit 17 or a sector gear that meshes with each other is used. The levers 11, 12, 14 are all configured in the shape of a fork in order to mount the switching contacts 516H7 and the springs loaded by them.

The spring 18 pulls the mutually connected ends of the levers 12, 14 into the contact support arm 4 so that the switching contact 6.
The ends of the levers 12, 14 supporting the switch 7 are always subjected to a moment in the direction of the switching contact 5. Switching contact 5
It is loaded in the direction of the insulation sleeve 1 by means of a spring (not shown) and, due to the geometrical arrangement of the lever 11, can only be moved approximately in the radial direction of the insulation sleeve 1 within its contact support arm 4. In FIG. 8, the leaf spring 19 axially presses the switches 8, 9, 10 which hold the switching contacts 5, 6, 7 to ensure a low resistance to the lead wire of the switching contacts.

Starting from the position of the load tap selector shown in FIG. 1, upon switching the switching contact 5 from tap contact 2 to tap contact 3,
When the switching contact 7 rides on the tap contact 2, it is lifted, and at this time the double-armed lever 2 is tilted clockwise.

At the same time, the engagement of the pin 16 with the slots 1 and 17 causes the double-armed lever 14 to tilt counterclockwise about its axis 15, thereby lifting the switching contact 6. FIG. 2 shows the position just before the switching contact 7 completely rides over the tap contact 2. At the same time, up to this point, contact between switching contact 5 and tap contact 2 always exists.

As the switching progresses further, the switching contact 5 separates from the tap contact 2, and the bIC between the loads is taken over by the switching contact 7.

Due to the tilting movement of the double-armed levers 12 and 14, the switching contact 6.7 moves away from the central switching contact 5, so that when the switching contact 5 is disengaged from the tap contact, as shown in FIG. It's coming just before.

When the switching contact 6 accidentally rides on the tap contact 3, the inner and outer switching contacts 6.7 are in contact with the two mutually adjacent tap contacts 2 and 3, respectively, as shown in FIG. Thereby the tap contact 2 of the transformer not shown
The winding portion between and 3 is short-circuited and a corresponding tap-to-tap short-circuit current flows. The magnitude of this inter-tap short circuit current is limited to an allowable level by a current limiting resistor (not shown) connected in series to the switching contacts 6 and 7.

Immediately after the switching contact 6 rides on the tap contact 3, the switching contact 7 is removed from the tap contact 2, thereby breaking the armor connection between the taps. In this position shown in FIG. 5, only the switching contact 6 conducts the load current.

However, in the next step, the position shown in FIG. 6 is immediately reached, in which the central switching contact 5 is connected to the tap contact 3 and the load current no longer flows through the switching contact 6.

While the switching contact 5 moves further toward the center of the tap contact 3, the switching contact 6 rolls across the corner of the tap contact 30, so the double-arm lever 14 is tilted in the direction of rotation by the shaft 18 that loads it. be done. At this time, the dual-arm lever 12 is tilted counterclockwise by the connection between the pin 16 and the slit 17, so that the switching contact 6°7 is connected to the tap contact 3 shown in FIG.
come to a position next to

The individual switching contacts 5, 6, 7 should each have as large a breaking capacity as possible when breaking the arc during opening. For this purpose, it is preferable to open the contacts at a speed as high as possible so that a sufficiently large contact distance can be obtained within a sufficiently short period of time.

From this point of view, the tap contacts 2 and 3 are preferably convex towards the axis of the insulating tube l, so that at the end of switching the tilting movement of the double-shouldered lever is prevented so that the switching contacts 6 and 7 of It is exposed faster than it comes off the tap contact that is in contact with it.

〔Effect of the invention〕

The present invention has tap contacts arranged on the circumference and connected to the taps and switching contact groups for the three current branches provided on a common contact support arm and rotating simultaneously on an arc. In a load tap selector of a transformer for switching from one tap to an adjacent tap, each inner and outer switching contact is supported by the free end of one arm of one double-armed lever, and these two-armed levers The ends of the other arms are mechanically coupled to each other, and the inner and outer switching contacts are tilted by a spring force in the rest position of the contact support arm to a position near the side of the then selected fixed tap contact, and When one of the switching contacts runs over a fixed tap contact, the lever arm supporting the immediately outer switching contact is tilted in opposite directions against the spring force, and the lever arm supporting the immediately outer switching contact is tilted in opposite directions. is arranged so that it moves away from the central switching contact.

With this configuration, on the one hand, due to the mutual connection of the two double-armed levers with the immediate outer LIJ switching contacts, the spacing between the outer switching contacts is relatively large during switching, thereby resulting in a large spacing between the fixed tap contacts. can bridge the
On the other hand, in the rest position the immediately outer switching contact approaches the currently selected tap contact, so that a large distance is maintained between the movable vj switching contact and the tap contact then adjacent thereto.

If the diameter of the insulating tube that fixes the tap contact is determined by the stiffness, the insulation distance increases, making it possible to handle higher operating voltages.

[Brief explanation of the drawing]

The drawings show a contact system of an embodiment of a load tap selector according to the invention, and FIGS. 1 to 7 are plan views of the contact system showing the operational sequence of switching from one tap contact to an adjacent tap contact; FIG. 8 is a sectional view along the roller axis and lever axis of the contact system. In the drawing, 2 and 3 are tap contacts, 4'tL contact support arms, 5 and 6.7 are switching contacts, 8, 9, 10, ]
, 3, 15 is the shaft, 11 is the single lever, +2,
H is a twin lever, 16 is a pin, 17 is a slit, 18
It's a spring.

Claims (1)

[Claims] 1) A switching contact for three current branches arranged on the circumference and connected to the tap or provided on a contact support arm common with the tap contact and rotating simultaneously on an arc; A transformer load tag selector for switching from one tap to an adjacent tap, having a group of When the skin support arm rotates, the central switching contact moves only approximately radially relative to the contact support arm, and when the contact support arm rotates, the switching contacts on both rows are pivoted on the contact support arm. in which the switching contact group is tilted with respect to the contact support arm on a lever mounted, and the movement of the switching contact group relative to the contact support arm is controlled by a fixed tap contact, which at the same time serves as a cam;
The switching contacts of each row are each supported by the free end of one arm of a double-armed lever, the ends of the other arms of these two-armed levers being mechanically coupled to each other, and the switching contacts of both rows are the contact is tilted by a spring force in the rest position of the contact support arm to a position near the side of the then selected fixed tap contact;
When one of the switching contacts on both rows runs over the fixed V tap contact, the lever arms supporting the switching contacts on both rows are tilted in opposite directions against the spring force, and the switching contacts on both rows are tilted in opposite directions. A load tag selector for a transformer, characterized in that a lever arm supporting the transformer moves away from a central switching contact. 2. In the device according to claim 1 and further recited in 4[V,
A load tap selector for a transformer, characterized in that the spacing between the switching contacts of both rows in the mutually distant positions during the switching process is at least 25 times larger than the spacing in the rest position. 3) In the device according to claim 1 or 2, the levers supporting the switching contacts on both rows are arranged symmetrically around two shafts with respect to the central switching contact. A load tap selector for a transformer, characterized in that it can be tilted. 4) In the device according to any one of claims 1 to 3, the levers supporting the switching contacts on both sides are mutually equal and form a fork with two arms, and , via coupling devices of the same shape or of mutually symmetrical construction with respect to the central switching contact. A load tap selector for a transformer, characterized in that the load tap selectors are coupled to each other with play. 5) A load tap selector for a transformer according to any one of claims 1 to 4, characterized in that the switching contacts are formed as rollers. 6) Claims 1 to 5 of the claims 1.
In the device according to claim 1, the central switching contact is supported by a single-armed lever tiltable about an axis guiding one of the two double-armed levers and via a spring generating the contact pressure. A load tap selector for a transformer, characterized in that it is supported by a contact support arm. 7) In the device according to any one of claims 1 to 6, the shaft guiding each lever is a fixed tap contact at a distance larger than the shaft of the roller serving as a switching contact. A load tap selector for a transformer, characterized in that the load tap selector passes by the transformer. 8) A transformer according to any one of claims 1 to 7, characterized in that the surface of the fixed tap contact is convex in the direction of the rotation axis of the contact support arm. load tag selector.