RU202276U1 - HIGH VOLTAGE DEVICE CONTACT KNIFE - Google Patents

Abstract

The utility model relates to electrical engineering and can be used in the knives of disconnectors and earthing switches. The contact knife contains cantilevered lamellas with a contact surface, grouped in rows. Each of the rows of lamellas is enclosed in a common casing that prevents the rows of lamellas from freezing to each other. The casing has a surface with low ice adhesion. The casing is located at least from the point of attachment of the lamellas to the contact surface or can be located along the entire length of the lamellae with a cutout on the contact surface. For drainage of water from the inner volume of the casing, holes are made in its lower part.

Description

The utility model relates to electrical engineering, in particular, to devices for switching an electrical circuit. The claimed technical solution can be used in the design of the main blades of disconnectors and in the contact blades of earthing switches, both free-standing and built into the disconnector.

Known contact system of devices (disconnectors and earthing switches), which includes rotary knives with cantilevered lamellas and a rotary or fixed knife with a receiving contact. When the device is turned on, the receiving contact is cut (included) into the mentioned lamellas (for example, see TI-092-2009 Technical information. AC disconnectors RGP-SESH 35 kV, https://www.electroshield.ru/catalog/razyediniteli-i- vla / razediniteli-naruzhnoy-ustanovki-35-kv /).

Above the receiving contact, a visor made of a metal sheet is fixed to protect the lamella contacts from icing, and a metal casing is also used. In this case, the area of the metal casing reaches a significant size, which leads to a large mass of ice and snow, which can accumulate on the casing, and also significantly increases the wind load on the apparatus.

Also, to protect the lamellas from icing, each of them can be coated with compositions and / or materials having low adhesion to ice. The disadvantages of this method include a significant resistance of ice to the spreading of the lamellas in the case of their "monolithic". When the device is turned on, the receiving contact, entering the gap between the lamellas, pushes them apart. If there is a solid ice bridge between the lamellas, then it must be broken, so that the lamellae have the opportunity to move apart. Despite the fact that the existing coating significantly reduces the resistance of ice to tearing due to a decrease in the adhesion force to the rods, nevertheless, the available cross-sectional area of the ice between the rods can reach a significant value, and this increases the resistance of the ice to breaking and splitting. This effect is especially noticeable if the distance between adjacent lamellas is less than the resulting ice wall, since in this case it is possible to completely fill the space between the lamellas with ice - monolithization.

Closest to the claimed utility model is a contact knife of a high-voltage apparatus [Patent for invention RU 2320047, prior. 20.11.2006, publ. 03/20/2008, H01H 31/00 (2006.01)], containing a current-carrying knife with lamellas cantilevered on the current-carrying knife and forming a detachable contact part. Moreover, each of the lamellas has an electrical contact surface, a receiving contact and an anti-ice casing. The casing is made in the form of a shell installed on the detachable part of the lamellas, and in the shell, at least above the specified electrical surface, a through cut is made. The casing can be made of a material with low adhesion to ice, a heat-shrinkable material, as well as a cellular structure. The casing can contain through holes located along the longitudinal axis of the lamellas.

The disadvantage of the known solution is that with a close arrangement of rows of lamellas, an almost monolithic ice mass may appear, covering the rows both outside and filling the gaps between the lamellas without breaks.

When creating a utility model, the task of increasing the efficiency of the contact knife of a high-voltage apparatus (disconnector, grounding switch) during icing was solved.

The technical result achieved in the implementation of the utility model is to simplify the ice cracking when sliding the lamellas. There is a weakening of the bond of ice with the lamellas in the contact zone, and, consequently, the prevention of continuous freezing of the rows of lamellas among themselves.

The inventive contact knife of a high voltage apparatus contains cantilevered lamellas with a contact surface, grouped in rows. The contact knife differs in that each of the rows of lamellas is enclosed in a casing common to the lamellas of the row. In the presence of a common casing, due to a decrease in the cross-sectional area of the ice monolith, along which it is cracked, the force required for cracking is reduced, thus cracking is simplified.

Moreover, the casing is made with a surface having low adhesion to ice. In particular, it can be made of a material with low adhesion or have a surface of the casing coated with a material with low adhesion to ice. Poor adhesion weakens the bond of ice to the lamellas, which also makes splitting easier.

Preferably, the cover is located at least from the point of attachment of the lamellas to the contact surface, which is a universal solution for different types of contact blades and provides optimal protection of the lamellas. The casing can be located along the entire length of the lamellas, while in order to ensure electrical contact with the receiving contact, as well as to protect the casing when moving the moving parts of the apparatus at the point where the lamels touch the receiving contact, a cut is made in the casing.

To drain water that has flowed into the casing, special holes can be made in its lower part, which helps to remove water and thereby minimize its accumulation inside the casing, preventing the formation of a continuous ice monolith.

Thus, the efficiency of protection against icing of all lamellas is increased with insignificant efforts of breaking the ice crust and a simple design of the anti-ice casing. The casing contains a minimum number of parts and has a minimum mass, since its thickness can be insignificant with a low material density.

Monolithic areas of ice subject to destruction when switched on are located outside, that is, around a row of lamellas, and from the inside (between the lamellae of a row) along the direction of contact movement, the ice mass is completely delaminated by the casing material. Thus, the inner layers of ice are able to relatively easily move and squeeze outward when the device is turned on.

The essence of the claimed utility model is illustrated by drawings, which show:

- in Fig. 1 - contact system of the high-voltage apparatus when the casing is made along the entire length of the lamella;

- in Fig. 2 - section along А-А with a view of the place of electrical contact of the lamellas (rods) and the receiving contact;

- in Fig. 3 - view B with variants of the drainage holes,

3а - version with round holes,

3b - option with slots;

- in Fig. 4 - surface line of the minimum cross-section of the ice monolith,

4а - using a casing common for a number of lamellas,

4b - without using a common casing or using a casing for each lamella separately (known solution).

To confirm the possibility of the utility model realizing its purpose and achieving the declared technical result, we will consider an execution option.

The contact system of the high-voltage apparatus (disconnector, earthing switch) contains a current-carrying knife 1 with cantilevered lamellas 2 (finger contacts). Lamellas 2 are grouped in opposite rows, in particular in two rows. The second current-carrying knife 3 has a receiving contact 4. When using a contact knife in the ground electrode, the function of the current-carrying knife 3 is performed by the current-carrying bracket. The receiving contact 4 is protected by a conventional sheet metal casing (not shown in the figures).

Rows of lamellas 2 are protected by anti-icing covers 6 in the form of a shell, in which each row of lamellas 2 is enclosed, that is, each row of lamellas 2 has its own casing 6 common for the lamellas of the row 6. The casing 6 can be located along the entire length of the lamellas 2 or at least from places of their attachment (beginning of lamellas 2) to the contact surface 5.

The electrical connection of the receiving contact 4 with the lamellas 2 is carried out through the contact surfaces 5 of the lamellas 2. If the casing 6 is made of such a length that it overlaps the contact surfaces 5 (for example, the casing 6 along the entire length of the lamellas 2), then at the point of contact of the lamellas 2 and the receiving contact 4 a transverse cut 7 is made in the casing 6. The size of the cut 7 on the casing 6 depends on the mutual movement of the contacts when turned on. For example, on the knives of the 110 kV disconnector, it is impractical to make covers up to the end of the lamellas and make a cutout in it for the contact surface. It is advisable to limit the length of the casing to the point of contact. In this case, in the apparatus with a different approach of the lamellas to the contact, a cut can be made, both partial and to the end of the casing.

The casing 6 with a length up to the contact surface 5 provides optimal protection of the lamellas 2 against freezing, since most of the length of the lamellas 2 is covered with a casing 6. When the casing 6 is made along the entire length of the lamellas 2, their maximum protection is achieved, but such a design, as indicated above, is impossible for some known lamella configurations and further requires a cutout 7 to provide electrical contact.

Water and then ice deposits can accumulate inside the casing, which accelerates the growth of the ice monolith and slows down its disappearance (melting), the stability of the electrical contact decreases, the mass of the knife increases, and due to constant contact with water, the elements of the knife can corrode. In order to minimize the possibility of ice deposition inside the casings 6 if their position is such that the water that has flowed inside has the ability to accumulate, drain holes 8 are made in the lower part of the casings 6 (see Fig. 3a). The drain holes 8 can be made in the form of slots, for example, as in FIG. 3b.

Lamellas 2 can have different designs and shapes. They can be made in the form of rods with round, rectangular, teardrop and other shapes.

The casing 6 must have a surface with low adhesion to ice. For this, it can be made of materials with low adhesion to ice, or it can have a coating of its surface from a material with low adhesion to ice. Moreover, low adhesion is characterized by an effective value less than the cohesion of ice at the same temperature. Such materials can be various kinds of fluoroplastic compositions, organosilicon rubbers, fluoropolymer compositions, polyethylene and others.

The fastening of the covers 6 to the lamellas 2 can be done in various ways: by fitting into an interference fit, using pins, rivets, including plastic ones, screws, clamps, glue, etc. The fastening of casings 6 made of a heat-shrinkable material, for example, of a fluoropolymer composition, on a number of lamellas 2 is carried out by heating the casing previously put on the lamella to a temperature of about 200 ° C, due to which the inner size of the casing 6 decreases, and it covers the lamellae 2 with an interference fit.

In addition, a casing with the desired surface properties can be obtained by applying a non-water-wettable material with low adhesion to ice on the outer surface of the casing 6 made of a material that does not have the required properties, for example, sheet metal.

The casing can also be made of cellular materials, reinforced or composite materials with an adhesive layer, etc.

The contact system of the high-voltage device works as follows.

In normal mode, without icing, the receiving contact 4 of the current-carrying knife 3 enters between the lamellas 2 of the current-carrying knife 1. In this case, the electrical contact surface 5 of each lamella 2 is in unhindered contact with the receiving contact 4, since there are cutouts 7 in the anti-ice covers 6 of the lamellae 2 (cm Fig. 2), or the casing 6 is made in length up to the contact surface 5. Thus, reliable electrical contact between the current-carrying knives 1 and 3 is ensured.

Under unfavorable conditions, when icing forms on parts of the high-voltage apparatus, the ice crust grows, including on knives 1, 3 and casing 6.

The water flowing into the shells 6 flows out through the drain holes 8 (slots 8). This reduces the volume of deposits inside the casing 6, which form layers of ice with low adhesion, as well as voids, dramatically reducing the rigidity and strength of the ice monolith and, accordingly, its resistance to splitting.

When the device is turned on, there is a slight chipping of ice from the surface of the casings 6 due to the low force of ice adhesion to their surface. Ice from the contact surfaces 5 of the lamellas 2 is also relatively easy to remove due to the fact that these surfaces 5 are relatively small and, as a rule, are covered with grease, which also makes the adhesion of ice to them very low.

If the thickness of the ice wall exceeds half the distance between the rows of lamellas 2, then it is possible to completely fill the space between the lamellas 2 with ice. In this case, when the device is turned on, it becomes necessary not only to break off the ice from the contact surfaces 5, but also to split the entire ice monolith 9 (see Fig. 4) due to the need to move the rows of lamellas 2 from each other (moving the lamellas apart). In this case, the value of the minimum cross-sectional area of the monolith (the smallest possible area), along which it splits, becomes essential. Figure 4 shows the line 10 of the surface of the minimum cross-section of the monolith in the case of using lamellas 2 with the casing 6 (Fig. 4a) and without it (Fig. 4b). As can be seen when comparing the figures, even when individual lamellas 2 are coated with a material with low adhesion to ice, the total length of the trail of the splitting surfaces on the secant plane in the absence of the casing 6 (Fig.4b) is greater than in the presence of the casing 6 (Fig.4a). This means that the total cross-sectional area of the ice monolith 9 in the presence of the casing 6 will be less than without the casing, and, therefore, the required splitting force will also be less in the presence of the casing 6.

The utility model makes it possible to reduce the effort required to break ice by reducing the adhesion of ice to surfaces, as well as reducing the ice cross-section along the line along which breaking will occur. Thus, it simplifies the chipping of ice from the working surfaces of the contact knife, that is, increases the efficiency of its operation in icing conditions.

Claims (6)

1. Contact knife of a high-voltage device, containing cantilevered lamellas with a contact surface, grouped in rows, each of which has a casing common to the lamellas of the row with a surface having low adhesion to ice. 2. A contact knife according to claim 1, characterized in that the casing is located at least from the point of attachment of the lamellas to the contact surface. 3. The contact knife of claim. 2, characterized in that the casing is located along the entire length of the lamellas, while a cutout is made in the casing at the location of the contact surfaces. 4. The contact knife of claim. 1, characterized in that the casing has holes in its lower part for drainage of water that has got inside the casing. 5. Contact knife according to claim 1, characterized in that the casing is made of a material with low adhesion to ice. 6. The contact knife of claim. 1, characterized in that the casing is coated with a material with low adhesion to ice.

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