EP2923367B1 - Spring control device for a circuit breaker - Google Patents

Description

Field of the invention

The invention relates to the field of medium and high voltage electrical distribution networks, and in particular spring control devices for circuit breakers.

Prior art and problem

In general, the circuit breakers used in the substations are coupled with control devices. These provide energy through a couple, to close and open the movable contacts of the circuit breaker. These control devices can be hydraulic, pneumatic or spring type.

In the case of the development of spring-type control systems, several aspects or criteria are to be considered: operation, performance, possible cost reductions, safety, security, accessibility.

In particular, there is a need for spring-loaded control devices for circuit breakers with two-period cut-off time. High-voltage circuit breakers, used in electrical networks at 60 Hertz, must react in a timely manner short, which is limited to 33.3 milliseconds. To overcome a fault, at a frequency of 60 Hertz, the speed of movement of the contacts in the circuit breaker must be optimized. The newly developed spring control devices must therefore have an increased speed of movement of the moving contacts inside the circuit breaker, without having to use springs of the "much higher energy" type. In addition, the spring control devices that one wishes to develop must have a life of 40 years, or a number of opening / closing operations of the order of 10,000 times.

However, in Max SARDOU's document entitled "Light weight, low cost, composite coil springs are a reality, SAE 2005", we show the use of different types of composite springs, such as coil springs and bent springs. These C- or Q-shaped springs were tested during fatigue tests.

• un fluage minimal ;
• une haute fréquence de résonnance ;
• la possibilité d'être utilisé dans des milieux plus ou moins corrosifs ou pollués.

Among the advantages of this type of spring, we can note:

• minimal creep;
• a high resonance frequency;
• the possibility of being used in more or less corrosive or polluted environments.

On the other hand, the European patent document EP-0 658 909 and the French patent document FR-2,840,726 show mechanical controls to spring for medium or high voltage circuit breakers. In this type of mechanism, the spring is connected to the drive shaft, by means of tension devices, such as a chain. Such a chain is attached to the drive shaft via a lever system. In order for the chain to apply torque to the drive shaft, a pulley is used to change the chain of direction. One end of the spring is mounted on the housing of the device. The other end of the spring can therefore be compressed by the chain. It uses a toothed wheel rotated by the spring from a first angular position to a second angular position and a pinion cooperating with the toothed wheel. The type of spring used in such a mechanism is of the helical type. However, this type of spring is relatively heavy and expensive.

The Belgian patent BE 662 849 discloses an Ω-shaped spring used in actuating the movable contacts of an electrical switching device.

Finally, the patent document US-7,311,124 shows a method of manufacturing wire to form springs, among others compression springs. However, it is this type of spring that is used in spring loaded control devices.

There is therefore a need to equip the spring control devices for medium and high voltage circuit breakers, other than by this type of springs.

Summary of the invention

For this purpose, the main object of the invention is a spring-loaded control device for a circuit breaker operating in a high or medium voltage network, the device comprising a drive shaft to allow to actuate very quickly at least one contact. mobile circuit breaker.

According to the invention, the spring is a curved composite spring, C-shaped or Ω.

• une première extrémité, qui a une forme en crochet et qui est fixée à un bâti du dispositif de commande ; et
• une deuxième extrémité, qui a une forme de crochet et qui est mobile, est fixée par pivotement à une extrémité distale d'un système à leviers fixé, lui-même, de manière solidaire à l'arbre d'entraînement par son autre extrémité.

In the main embodiment of the invention, the spring comprises:

• a first end, which has a hook shape and which is fixed to a frame of the control device; and
• a second end, which is hook-shaped and movable, is pivotally attached to a distal end of a lever system attached, itself, integral with the drive shaft at its other end.

In the preferred embodiment of the invention, the control device has a frame consisting of two parallel flanges between which is fixed a fixed rod, and fixed to a first end of the spring, the second end of the spring being always placed between the two flanges constituting the frame of the device.

List of Figures

• figure 1, en vue cavalière, le ressort utilisé dans le dispositif de commande selon l'invention ; et
• figure 2, en vue cavalière, un exemple de réalisation du dispositif de commande selon l'invention.

The invention and its various technical features will be better understood on reading the following description, accompanied by two figures respectively representing:

• figure 1 , in a cavalier view, the spring used in the control device according to the invention; and
• figure 2 , in a cavalier view, an exemplary embodiment of the control device according to the invention.

Detailed description of an embodiment of the invention

On the figure 1 , Figure 1 a spring 1 C-shaped or omega (Ω). It is specified that it is, according to the invention, spring type composite. A composite material that can be used to form the spring is a material comprising a fiberglass matrix and epoxy resin. Each of these ends 2 and 3 has a hook shape. The spring 1 is in the form of a curved blade.

The first end 2 is fixed to a fixed rod 5, fixed relative to the frame of the control device. The second end 3 hook-shaped is movable in that its position can vary by relative to the fixed rod 5. Thus, the first end 2 of the spring 1 remains in a fixed position.

The second end 3 of the spring 1, which is also hook-shaped, is fixed around a movable rod 4 which is movable in position. Indeed, this movable rod 4 is placed at the end of a lever system 7, that is to say placed between the two distal ends of two levers 7A and 7B which are parallel. The other ends of these two levers 7A and 7B are attached to a drive shaft 6, which is notched or grooved, so as to be integral in rotation with the latter.

Spring 1 is loaded in compression. At this stage, the second end 3 of the spring 1 has a first determined position relative to the first end 2 of the spring 1. When the spring 1 is suddenly discharged, that is to say, it relaxes, the second end 3 moves a little time away from the first end 2 of the spring 1. In other words, the radius of the curvature of the spring 1 increases slightly. To better define this deformation, it can be said that the central portion 8 of the spring 1 is close to a plane defined by the axes of the two fixed and movable rods 5 and 4.

Due to this relaxation, the movable rod 4 changes position and slightly rotates the lever system 7, thereby rotating the drive shaft 6. Two arrows show the downward movement of the central portion 8 of the spring 1 and the rotation of the drive shaft 6. The securing of the drive shaft with the lever system 7 is done by means of a notching system and / or by means of splines.

With reference to the figure 2 , the spring 1 is inserted in a spring drive device, used to operate the high voltage circuit breakers. We can also refer to the European patent document EP-0 658 909 which shows such a type of control device. Here the spring 1 is integrated between the two flanges 10A and 10B of the frame of the device, which are placed in parallel. The spring 1 is integrated in part inside the control device.

We distinguish, on this figure 2 , the stationary rod 5 fixed to the first end 2 of the spring 1 which is fixedly positioned relative to the two flanges 10A and 10B of the frame of the control device. It therefore remains stationary during the operation of the spring 1.

The lever system 7 protrudes with respect to the two flanges 10A and 10B, as does the movable rod 4, which is fixed to the second end 3 of the spring 1. The position of the lever device 7 therefore depends on the fact that the spring 1 is charged or not.

Since it has not been envisaged to increase the height of the flanges 10A and 10B, the spring and the lever device protrude from above with respect to the frame of the control device. One could consider increasing the height of the two flanges 10A and 10B so that they completely surround the spring 1 and the lever device 7.

The spring 1 is therefore used for opening operations of the circuit breaker, requiring a very high speed of intervention.

Concerning the closures of the circuit breaker, a conventional spring, placed in a housing 11, fixed to the frame on the side thereof, is used in a known manner. The closing spring is generally a conventional helical spring.

Advantages of the invention

The invention of a composite spring shaped curved C or Ω allows a reduction of 10% of the mass of the assembly.

où f est la fréquence de résonance du ressort et m la masse du ressort. Ceci peut avoir une importance importante lors de la conception du dispositif de commande à ressort.Due to this mass reduction, the resonance frequency of the spring is increased. Indeed, considering the following formula: $$f\alpha \frac{1}{\sqrt{m}}$$

where f is the resonant frequency of the spring and m the mass of the spring. This may be important in the design of the spring loaded controller.

The use of "composite" type springs makes it possible to increase the life of the control device. It is recalled that a spring of the type "curved", C-shaped or Ω, type "Composite" can endure stress tests with 6,000,000 cycles.

This type of spring has excellent creep resistance over time.

Compared to the solution presented in the document EP-0 658 909 no chain is used in the control device according to the invention for connecting the spring used to the drive shaft. This minimizes the potential failure rate of the set.

If this type of control device has been designed to equip gas-insulated circuit breakers (GIS), but it can also equip air-insulated circuit breakers, those with oil bath or those with low volume of oil.

The applications of all these implementations are relatively diverse as they relate to both outdoor and indoor installations.

Claims (2)

1. A spring-loaded control device for a circuit breaker in a high- or medium-voltage electrical network, the device including a drive shaft (6) for enabling very fast actuation of at least one movable contact of the circuit breaker;
   the control device being characterized in that the spring (1) is a composite "curved" spring of the C-shape or Ω-shape type, and in that the spring has:

   • a first end (2) in the shape of a hook and fastened to a housing (10A, 10B) of the control device; and

   • a second end (3) in the shape of a hook that is movable and that is pivotally fastened to a distal end of a lever system (7), the distal end of the lever system being constrained to rotate with the drive shaft (6) via its other end.
2. A control device according to claim 1, characterized in that the housing is constituted by two parallel plates (10A, 10B) between which there is fastened a stationary rod (5) that is fastened to the first end (2) of the spring (1), the second end (3) of the spring (1) being movable between the two plates (10A, 10B).

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