JPS60161604A - On-load tap changer of transformer - Google Patents

Abstract

1. Selector switch for tapped transformers for switching over from one tapping to the next, having fixed contacts (1) arranged on a circle and connected to the tappings, and having switching contacts (3, 4, 5) for three branch circuits on a common contact carrier, which switching contacts can be rotated at the same time on the circle and are represented by rollers, whereby : all the switching contacts (3, 4, 5) carry in their resting position the potential in each case of the same step contact (1), when the contact carrier is rotated, the switching contacts (3, 4, 5) loaded with spring force (12, 14) are moved, with regard to the contact carrier, essentially only in the radial direction, and the movements of the switching contacts (3, 4, 5) with regard to the contact carrier are controlled by the fixed step contacts (1) representing at the same time cams, characterised in that : the contact carrier has guide rails (6) aligned radially to the circle of the step contacts (1), for at least two contact slides (9, 13), a first contact slide (13) carries a main switching contact (3), and another contact slide (9) carries two resistance contacts (4, 5) flanking on both sides the main switching contact (3) in the direction of rotation, movements, occurring in operation, of the contact slides (9, 13) in opposite directions on the guide rails (6) are limited in both directions by limit stops (15, 16) on the contacts slides (15, 16) themselves, so that, when the limit stops (9, 13) lie next to each other, in each case all the spring forces (12, 14) assigned to the switching contacts (3, 4, 5) load the one switching contact (3, 4, 5) which is just carrying current, and the guide rails (6) and the contact slides (9, 13) engage with one another, guiding each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an on-load tap changer for a transformer for switching from one tap to an adjacent tap.

[Prior Art] In order to switch from one tap to an adjacent tap, a fixed tap contact arranged on one circumference and connected to the tap, and a fixed tap contact arranged on a common contact support and connected to the said circumference are used. An on-load tap changer for a transformer with roller-shaped switching contacts for three simultaneously rotatable current branches is known from European Patent Application No. 0 029 467. In this tap changer, all switching contacts each have the same tap contact potential in their rest position, and when the contact carrier pivots, the central switching contact moves primarily in the radial direction relative to the contact carrier. , when the contact support rotates, the switching contacts on both rows on the lever supported by the contact support rotate relative to the contact support, and the movement of the switching contacts relative to the contact support simultaneously acts as a cam. controlled by fixed tap contacts that perform the function.

German Patent No. 2,914,928 discloses a structure in which a roller-shaped movable contact is supported at the bending point of a rectangular lever for the on-load tap changer C2. In this construction, too, the stationary contacts serve as cam tracks for controlling the movement of the contact rollers perpendicular to the opening and closing blood. each square lever supporting a contact roller is supported by the end of its leg on a rotatable contact support;
Each other leg also carries a helical spring in order to generate the necessary contact force between the contact roller and each stationary contact that is rubbed by the contact roller.

Usually, in an on-load tap changer, each outer switching contact is connected in series with a current limiting resistor. As a result, the voltage vector diagram of the switching process is helical, and this voltage distribution is particularly advantageous with regard to the permissible switching capacity of the individual contacts. In the rest position of this known on-load tap changer, the operating current of the transformer flows from one fixed contact through the centrally arranged main switching contact, while the two outer switching contacts act as resistance contacts. , no current flows in the rest position of the tap changer. In order to ensure switching without current interruptions, at least one of the movable switching contacts must not be in contact with a fixed contact in any intermediate position during the movement process: I''L.

That is, in the intermediate position, before the main changeover contact is disconnected from the fixed contact through which current is flowing (2. One resistive contact must be placed on this fixed contact).Similarly, (2. Before the resistive contact through which the current is flowing is removed from the fixed contact through which the current is flowing, the second
The resistive contact of C: must already be in contact with the secondary fixed contact C:.

In order to satisfy this condition C: In this case, the width of the fixed contact must be larger than half the distance between the contact rollers that serve as resistance contacts, and the distance between these contact rollers must be the distance between two adjacent fixed contacts. Must be bigger.

Introduction C: The disadvantage of the contact device described is its relatively bulky construction and, in addition, it is difficult to use when very high operating voltages are applied. Contact devices with contact rollers supported on square levers are unsatisfactory in that they require different cam trajectories for the control of individual contacts that are subordinate to the same contact support. This results in relatively high manufacturing costs, which are further increased by the fact that possible manufacturing tolerances have to be taken into account.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is to provide an on-load tap changer that has a compact structure, has a structure in which the outer surfaces of the contact support and the fixed contact are extremely flat, and at the same time can tolerate relatively large manufacturing tolerances. The object of the present invention is to provide such a contact device.

[Means for solving problems]

According to the present invention, the above-mentioned problem can be solved by providing at least two contact slots in the on-load tap changer mentioned at the beginning.
For the f da, the contact support is provided with a guide rail aligned in the direction of the circular profile of the tap contact, the first contact slider supporting the main switching contact and at least one other contact slider supporting the main switching contact. supports resistance contacts lined up on both sides of the rotating direction,
The relative movement that the contact slider undergoes during operation on the guide rail is limited in both directions by stops mounted on the contact slider itself, so that when the stops abut, all spring forces that are subject to the switching contact are then This is achieved by a telescopic fit between the guide rail and the contact slider.

According to an advantageous embodiment of the invention, the contact slider supporting the main switching contact is arranged between two guide rails, and the box-shaped contact slider surrounding them provides a common support for the two resistance contacts. fulfill the role of the body. At that time, a protrusion protruding perpendicularly from the contact slider supporting the main switching contact in the rotation direction (:) engages with a long hole in the box-shaped contact slider, and the end of this protrusion and the long hole connects to the slider on the guide rail. serves as a stopper to limit the relative movement of the

According to another advantageous embodiment of the invention, each contact slide is always pushed radially outwards by spring force, and the at least one guide rail is provided with an end stop for the box-shaped contact slide. The end stop prevents the contact slider from slipping out of the guide rail during assembly.

In a further advantageous embodiment C2 of the invention, the main switching contact consists of two contacts d-roller arranged spatially one after the other in the switching direction, each roller having a 'L are arranged on individually movable contact slides and/or the contact slides are supported on one another and on guide rails via rolling bearings.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings showing an embodiment of the on-load tap changer according to the present invention. 1st
2 to 4 are side views of the contact support shown in FIG. 1 in a series of switching positions. In the drawings, parts that are the same are given the same reference numerals.

The fixed tap contacts 1 are arranged on a circumference in a known manner, not shown, and are supported by insulating rods or cylinders forming a cylindrical cage. A fixed tap contact 1 is electrically coupled to the tap of the close tap winding.

In its rest position, the main switching contact contacts one of the tap contacts 1 at any given time and is itself electrically coupled to the load circuit.The main switching contact 3 is rotatably mounted on an axis 10. It is formed by a bearing roller and is movable in the radial direction by means of a spring 4 together with a contact slide 13 between guide rails 6 until the roller contacts the tap contact IC.

The guide rail 6 is a part of a stand 11, which is supported by an insulating cylinder 2 (2) provided at the center of the car. It is rotated through.

The stand 11 having the guide rail 6 and the contact slider 13 are surrounded by a box-shaped contact slider 9C2. The contact slide 9 supports resistive contacts 4 and 5 on either side of the main switching contact 3 in the direction of switching movement on a shaft 10 fixed therein. Resistive contacts 4 and 5 are also designed as rollers. Each resistance contact 4 and 5 usually forms a series circuit with one current-limiting resistor each, and this series circuit itself is in each case parallel to the main switching contact 3, so that in a certain switching position the series circuit is Alternatively, for a short time, a load current can be conducted between the two tap contacts 1 and a load circuit (not shown). - the box-shaped contact slide 9 is pushed in the direction of the fixed tap contact 1 by a compression spring 12; In order to limit this movement, a protrusion 16 protruding from the contact slider 13 in the switching direction (bilateral direction) is used.
It engages with the elongated hole 15 inside. In the rest position shown in FIG. increase

Before assembling the contact device into a cage made of insulating rods and supporting a fixed tap contact 1, the guide rail 6 must be removed in order to prevent the contact sliders 9 and 13 from falling off the guide rail 6 of the stand 11. An end stop 17 is provided at the end of at least one of the rails 'C', which limits the radial movement of the contact slide 9 and thereby allows the contact slider 9 to pass through a projection 16 projecting into the elongated hole 15. The contact slider 13 is also held indirectly.

During switching, for example by rotation of the insulating sleeve 2, initially only the main switching contact 3 rolls towards the side on the generally spherical contact surface of the fixed tap contact 1. However, before the main switching contact 3 disengages from the fixed ρ tap contact 1 through which current is flowing, for example, the resistive contact 4 reaches this tap contact (2), and this resistive contact rides on the fixed tap contact 1, The contact slider 9 is pushed in the direction of the rotating shaft of the insulating tube 2 against the force of the compression spring 12, and at the same time the contact between the protrusion 16 and the elongated hole 15 is eliminated.As shown in FIG. In this switching position, the load current is still flowing via the main switching contact 3, since the main switching contact still short-circuits the series circuit consisting of the resistance contact 4 and the current-limiting resistor.

The load current is commutated to the resistance contact 4 only after the main switching contact 3 has completely rolled away from the current-carrying fixed tap contact 1. In this switching position, the contact slide 13 rests on its projection 16 (the outer end of the slot 15), so that the force of the compression spring 14 now contributes to increasing the contact force of the resistance contact 4. Before the resistive contact 4 carrying the current flows out from the fixed tap contact,
After completion of the tap change, the resistive contact 5 abuts the next fixed tap contact 1 to take over the load current. During the very short time during which both resistive contacts 4 and 5 are in simultaneous contact with the two tap contacts 1, a cross current flows between the resistive contacts 4 and 5, which is limited by the current limiting resistor.

In the next switching process, when the resistive contact 5 rides on the newly selected fixed tap contact 1, the connection between the resistive contact 4 and the fixed tap contact 1 through which current was flowing is broken. After this cutoff has taken place (for the first time,
The main switching contact 3 reaches the fixed tap contact 1, which is in contact with the resistance contact 5. As a result, the series circuit consisting of resistance contact 5 and its associated current-limiting resistor (not shown) is short-circuited, and the load current is again diverted to main switching contact 3.

After tap switching is completed, both resistance contacts 4 and 5 are lined up again next to the fixed tap contact through which current is flowing.
These resistance contacts are again together with the contact slider 9! = Pushed radially outward (2) by compression spring 12, protrusion 16
contacts the inner end ζ of the elongated hole 15, and the spring force of the compression spring 12 contributes to an increase in the contact force of the main switching contact 3.

If the load current is very large or fixed tap contact 1
If the contact slider 13 is very wide, it is reasonable to divide the contact slider 13 and arrange the two main switching contacts 3 one after the other in the circumferential direction. Forcibly dividing the load current into a plurality of contact sliders operating in parallel is possible using the contact slider 13.
This is achieved by subdividing C2 parallel to the rotating plane.

C2, in order to facilitate relative movement between the contact slides 9 and 13 and the guide rail 6, regardless of the number of contact slides;
It is advantageous to provide some or all sliding tracks with rolling bearings. On the one hand, this results in reduced mechanical wear and on the other hand, increased service life and reliability.

Appropriate arrangement of the elongated hole 15 and the protrusion 16 (from the second point, the contact roller of the main switching contact 3 always rides up and comes off the outer corner of the fixed tap contact 1), while the rollers of the resistance contacts 4 and 5 2. It is possible to set the contact roller to run over or come off at an approximately midway point between the outer corner and the center of the fixed contact. This prevents burnout of the surface of the fixed contact caused by arcing. According to the invention, according to the invention, the load A very advantageous and simple construction can be obtained for the time tap changer, since in the rest position and in the first part of the switching process the main switching contact and the subordinate contact slider are connected to the fixed contact C: Supported,
Further, unless both resistance contact rollers contact the fixed contact, the contact slider of the resistance contact is supported in the radial direction by the contact slider of the main switching contact. However, if the contact roller of the main switching contact comes off the fixed contact, or the contact slider of the main switching contact is supported by the contact slider of the resistance contact in the radial direction, in that case both contact sliders just touch the fixed contact. radially supported via resistive contact rollers.

During the entire switching process, the two contact slides are thus supported in their radial position by the contact rollers, which are in contact with the stationary contacts from time to time. As a result, not only the manufacturing tolerances but also the arcs (and burnout of the contacts caused by switching) are compensated by the automatic radial adjustment system in each case, resulting in two important features of this system: It is something that is born.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a contact support of an on-load tap changer based on the present invention, and FIGS. 2 to 4 are side views of the contact support shown in FIG. 1 in a series of switching positions. 1...Tap contact, 3.4.5...Switching contact, 6.
・・Guide rail, 9.13・・Contact slider, 11・
...Base, 12.14...Spring, 15.16...Stopper, ]7...Terminal stopper. IG 1

Claims (1)

[Claims] 1) To switch from one tap to the next tap,
for a fixed tap contact (1) arranged on one circumference and connected to the tap and for three current branches arranged on a common contact support and simultaneously rotatable on said circumference; Load tap changer for a transformer with roller-shaped switching contacts (3, 4, 5), characterized in that - all switching contacts (L4* 5) are in their rest position (two identical in each case); the potential of the tap contact (1), - when the contact support is pivoted, the switching contact (3° 4.5) loaded by the spring force (i2.14) approximately radially with respect to the contact support; - the movement of the switching contacts (a, 4. 5) relative to the contact support is controlled by a fixed tap contact (1) which simultaneously serves as a cam; - at least two contact slides; For (!1, 13) (2) the contact support is provided with a guide rail (6) aligned in the radial direction of the circle of the tap contact (]), - the first contact slide (13) is connected to the main switching contact (); 3), and at least one other contact slider (9) is arranged on both sides of the main switching contact (3) in the direction of rotation ('4.
- The relative movement of the contact slider (9, 13) during operation on the guide rail (6) is controlled by the stopper (15, 16) provided on the contact slider (9, 13) itself. All the spring forces (12, 14) which are restricted in both directions and are therefore subject to the switching contacts (3, j, 5) upon the abutment of the stops (9° 13) are then applied to the switching contacts in which the current is flowing. Contacts (3, 4, 5): an on-load tap changer for a transformer, characterized in that: - the guide rail (6) and the contact slider (9° 13) fit telescopically; 2) Contact slider (13) that supports the main switching contact (3)
is arranged between the two guide rails (6), and a box-shaped contact slider (9) surrounding the two resistance contacts (4)
, 5). Tap changer according to claim 1, characterized in that it serves as a common support for the tap changers. 3) Contact slider (13) that supports the main switching contact (3)
A protrusion (16) protruding perpendicularly to the direction of rotation engages with the elongated hole (15) of the box-shaped contact slider (9), at which time the protrusion (16) and the end of the elongated hole (15) Guide rail (6)
3. The tap changer according to claim 1, wherein the tap changer acts as a stopper for limiting relative movement of the upper slider. 4) @Contact slider (9, 13) has spring force (12, 14)
) is always pushed outward in the radial direction. One guide rail (6) has an end stop (17) for the box-shaped contact slider (9).
), this end stop prevents the contact slider (9, 13) from being pulled out and falling off the guide rail (6) during assembly.
The tap changer described in any of paragraphs. 6) The main switching contact (3) consists of two contact rollers arranged spatially one after the other in the switching direction, each roller being independently mounted on two movable contact slides (13). The tap changer according to any one of claims 1 to 5. 7) The contact sliders (9, 13) are connected to each other and to the guide rail (6) via rolling bearings. A tap changer according to any one of claims 1 to 6, characterized in that the tap changer is supported by a tap changer. 8) The switching contact (3
, 4, 5), the main switching contact (3) rides on or comes off at the outer corner of the tap contact (1), and the resistance contact (4, 5) rides on or comes off at the outer corner of the tap contact (1). 8. The tap changer according to any one of claims 1 to 7, characterized in that the tap changer is mounted on or removed between a corner and the center.