JPH07153633A - On-load tap changer for on-load tap changing transformer - Google Patents

Abstract

PURPOSE: To offset the weight of a member to be driven, and to achieve same switching time, regardless of the switching direction. CONSTITUTION: In the case of an on-load tap switcher for a step-up transformer, a fixed tap contact is provided along a linear orbit, and it can be connected by a slidable switching mechanism. The switching mechanism is provided with an elevation carriage 3, which can be continuously driven and a member to be driven which rapidly follows-up after a storage has been released. An additional spring 11 is provided between the elevation carriage 3 and the member to be driven. The tension force of this additional spring changes relatively, based on the switching direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elevating carriage in which fixed tap contacts are provided along a linear trajectory and can be connected by a slidable switching mechanism so that the switching mechanism can be continuously driven. And a driven member that can be pulled up by the elevating carriage by using an energy storage device, and the driven member rapidly follows the elevating carriage after being released, and relates to a load tap changer for a load tap change transformer.

[0002]

2. Description of the Related Art Such a tap changer under load is WO
Known by 94/02955.

The load tap changer based on the rapid resistance switching principle is usually constructed as follows in order to switch from one tap of the load tap change transformer to the other tap without interruption. That is, fixed tap contacts, which are electrically connected to the conductors of the tap windings, are provided in a circular shape on the insulating material frame or insulating material cylinder in one horizontal plane or in a plurality of horizontal planes and are concentric. It is configured to be connectable by a rotatable contactor bridge operated by a drive shaft. In the case of a switching switch that combines tap selection with the original load current switching, the contactor bridge is operated after the release of the energy store (mostly spring force energy store) that is strained by the drive shaft of the switch. , Done abruptly.

Unlike this ordinary structure, WO 94/0
2955 describes a load contact tap changer for linear contactor operation. In this case, the fixed tap contact extends along the track into the switch and can be connected by a slidable switching mechanism. This switching mechanism is driven by the drive shaft.

The vertically slidable switching mechanism is a lifting carriage that can be continuously driven by a drive shaft, which preselects a new fixed tap contact, and can be lifted by a lifting carriage using a charge store. It is composed of a driven member. After being released, the driven member rapidly follows the lifting carriage, with the original load current switching from the previous tap of the tap winding to a new preselected tap. The switching element required for that purpose is a component of the driven member.

In this load tap changer, the driven member always comprises a number of different mechanical guiding elements and electrical contact elements, a switching element and means for operating this switching element, There is a drawback in that the mass becomes heavy. Thus, with each release, the spring-type energy store releases the same energy, so that the rapid upward movement of the driven member is slower than the downward movement. Because
This is because in the case of upward movement, the amount of energy of gravity of the driven member counteracts the amount of energy of the spring type energy storage device. On the other hand, these amounts of energy are added during the downward exercise. Such a switching speed, which depends on the switching direction, is undesirable. As in the case of the load tap changer operated by a rotatable horizontal contact bridge,
All switching should occur at least at approximately the same switching speed.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to cancel the weight of the driven member that rapidly follows in the linear load tap changer that moves in the vertical direction described at the beginning, and Should not affect the switching speed in a direction-dependent manner.

[0008]

An object of the present invention is to provide an additional spring between an ascending / descending carriage and a driven member, the additional spring being tensioned when the driven member moves downward, and added when the driven member moves upward. This is solved by reducing the spring tension. The dependent claims describe advantageous embodiments of the invention.

Due to the additional spring according to the invention between the lifting carriage and the driven member, as explained in more detail in the examples, the offset of the weight of the driven member and thus the equalization of the switching speed is independent of the switching direction. And it is achieved at low structural cost.

Tension springs and compression springs are suitable as additional springs. When a tension spring is used, this tension spring is provided between the lifting carriage and the driven member, in which case the lifting carriage is already directed towards the next fixed tap contact when preparing the downward switching movement. The tension spring is in the rest position when it is moving vertically downwards and the driven member is locked in its previous (above) fixed tap contact prior to release of the energy store. , Not pretensioned or only slightly pretensioned, and is tensioned during the subsequent rapid following of the driven member.

On the other hand, if a compression spring is used,
The compression spring is likewise in the rest position, i.e. in the decompressed state or in the fully decompressed state, when the member is in the above-mentioned position and is compressed, i.e. tensioned, in the subsequent rapid following of the driven member. .

This can be achieved by means of pivot points at the fixing points of suitable springs, which are selected in each case. The use of tension springs is advantageous when the tension spring does not require an additional longitudinal guide. On the other hand, in the case of a fixed length compression spring, there is a risk of bending during compression. This requires an additional longitudinal guide, for example a tube surrounding a compression spring. In particular, it has been found that the use of tension springs as additional springs makes it possible to almost completely cancel out the gravitational-dependent kinetic energy. By properly selecting the spring characteristics and varying the spring length, different weights and accumulator operating conditions can be accommodated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. First, the load tap changer shown in FIG. 1 will be described in detail.

Fixed tap contacts K (n-1), K
(N), K (n + 1), ... Extend laterally inside the load tap changer and are arranged vertically above and below. The tap contacts each consist of two contact sides parallel to each other. A screw spindle 2 is guided inside the load tap changer from a drive device 1 provided above. The screw spindle is equipped with a spring energy store. This accumulator comprises a tubular lift carriage 3. The lifting carriage is surrounded by a compression spring 4 and a screw spindle 2 which drives it. The lifting carriage 3 is insulated with an auxiliary contactor 5 for making a preliminary selection. Each of these auxiliary contacts is a fixed tap contact K (...
・) Scratch the contactor side. A vertically extending release contour 6 is also fixed to the lifting carriage.
The spring accumulator further comprises a substantially U-shaped driven member 7. The switching contacts, which connect the respective other contact parts of the respective fixed tap contacts K (...), are another component of the driven member 7, whereby together they release a sudden movement. To do. This tap contact is not visible in the figure. This is because, in the stationary position shown in the drawing, the auxiliary contacts 5 for preselection are in the same horizontal plane behind the auxiliary contacts 5.
The tension spring 11 has an upper side at a fixed point 1 of the elevating carriage 3.
1.1 is fixed and the lower end is a fixed point of the driven member 7.
2, fixed in a stationary position, i.e. under tension, when the preceding auxiliary contact 5 and the following switching contact make contact with the same fixed tap contact. That is, it is separated from the stationary position by a predetermined distance.

When switching is performed, the screw spindle 2 performs a rotational movement, and the annular lifting carriage 3 surrounding the screw spindle is continuously moved upward or downward depending on the rotation direction. Thereby, the upper support 4.1
Alternatively, the compression spring 4 of the accumulator, which is supported against the lower support 4.2, is compressed. That is, the spring energy store is compressed.

During this movement of the lifting carriage 3 relative to the driven member 7 which is still stationary, the rollers 8 of the release bolt 9 of the driven member 7 run on a release profile 6 which likewise moves vertically. To do. This release contour is a slanted section 6.1.
It has 6.2.

At the same time, the auxiliary contactor 5 which is insulated and connected to the elevating carriage 3 for preselection moves. That is, the auxiliary contact moves away from the original fixed tap contact K (n) and reaches the next fixed tap contact K (n + 1), K (n-1) above or below it.

Subsequently, the rollers 8 are each provided with an inclined portion 6.1.
Or reach 6.2. The release bolt 9 is a locking member 10. attached to the fixed tap contactor K (n). Sliding horizontally from n, the entire driven member 7 rapidly follows the preceding movement of the elevating carriage 3. This tracking is achieved by the locking member 10. n + 1 or 10. It is performed until it is locked again at n-1. The switching contacts then likewise move away from the previously fixed tap contact and reach one contact side of the new tap contact. The auxiliary contact 5 is already in contact with the side of the other contact.

When switching from K (n) to K (n + 1), the tensioning spring 11 is moved further in addition to its pretensioning force already present in the rest position by the lifting carriage 3 which makes a preselection. As the driven member 7 follows, the energy of the released compression spring 4 of the accumulator and the partially reduced tension spring 11 are added.

On the other hand, from K (n) to K (n-1)
At the time of switching to, the tension spring 11 is stretched by the lifting carriage 3 that makes a preselection, so when the driven member 7 follows, a portion of the kinetic energy is due to the partial tension of the tension spring 11. is necessary. The effects of weight are offset.

FIG. 2 schematically shows the above switching process. The characteristic curve of the course of force is apparent from FIG. It can be seen that the same situation occurs regardless of the switching direction. FIG. 4 shows the energy balance of the load tap changer described above.

E1 is the energy capacity of the energy accumulating spring 4, E2 is the energy capacity of gravity acting on the driven member 7, E3 is the energy capacity of the additional spring 11, and E
3'is the energy capacity of the additional spring 11 at the time of downward switching, E
3 ″ is the energy capacity of the additional spring 11 at the time of switching up. E ′ is the overall capacity at switching down, and E ″ is the overall capacity at switching up. At that time, E ′ = E ″, and further E
3 '+ E3 "= 2E2.

FIG. 5 schematically shows the situation that occurs when a compression spring is used instead of a tension spring. As already mentioned, when the compression spring is used, the pivoting point or the fixing point of the compression spring in the lifting carriage 3 or the driven member 7 can be selected differently. Furthermore, the characteristic curve of the acting force and the energy balance do not change.

It is not critical to the invention whether the additional spring in each case is completely or partially decompressed during the downward switching. That is, in order to obtain the desired compensation effect, the relative change in the pre-biasing force of the additional spring, which depends on the switching direction, is important.

[0025]

INDUSTRIAL APPLICABILITY The present invention has an advantage in a vertically moving linear load tap changer that offsets the weight of a driven member that rapidly follows, and that this weight does not affect the switching speed regardless of the direction. There is.

[Brief description of drawings]

FIG. 1 is a side sectional view of a tap changer under load according to the present invention having a tension spring as an additional spring.

FIG. 2 is a schematic diagram showing a switching frequency of such a tap switch during load.

FIG. 3 is a diagram schematically showing a characteristic curve of force acting at this switching frequency.

FIG. 4 shows a simplified energy balance at this switching frequency.

FIG. 5 schematically shows a second switching frequency of another load tap changer in which a compression spring is used instead of a tension spring as an additional spring.

[Explanation of symbols]

 3 Lifting carriage 7 Driven member 11 Additional spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Rolf Lauterwald, Federal Republic of Germany, 93186 Pettendorf, Thon-Datemer-Strasse, 9 (72) Inventor, Joseph Neumeier, Federal Republic of Germany, 93164 Wurdets-Enberg, Buchen Strasse, 38

Claims (3)

[Claims] 1. An elevating carriage, in which a fixed tap contactor is provided along a linear trajectory and can be connected by a slidable switching mechanism, and the switching mechanism can be continuously driven, and an energy storage device. And a driven member that can be pulled up by the elevating carriage, and the driven member rapidly follows the elevating carriage after being released. An additional spring (11) is provided between the driven members (7), the additional spring (11) is tensioned when the driven member (7) moves downward, and the additional spring (11) is moved when the driven member (7) moves upward. A tap changer under load, wherein (11) is reduced. 2. An additional spring (11) is provided substantially vertically, the upper end of which is fixed to the lifting carriage (3) and the lower end of which is fixed to the driven member (7). 1 load tap changer. 3. The load tap changer according to claim 1, wherein the additional spring (11) is a tension spring.