RU2449402C2 - Pole part of medium voltage switching device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to pole part of switching device with vacuum interrupter chamber enclosed into insulation material and containing fixed and moving contacts. Herewith, cast insulating housing is open in lower part in the area of moving contact or drive rod actuating moving contact. In the area of moving contact or at the place where it is coupled with drive rod (3), at least one vent hole (7) is made which passes through the wall of insulation (2), boundary zone between insulation and electric coupling part or through electric coupling part (4) of moving contact. The vent hole (7) is formed in coupling part (4) by means of at least one through bleed screw (8) with the help of which external contact is fixed in coupling part, at the same time, a hole accommodating at least one such bleed screw is through and connects external and internal areas of pole part to be ventilated.

EFFECT: reducing pole parts heating during operation and obtaining higher allowable nominal current load.

5 cl, 1 dwg

Description

The invention relates to the pole part of a medium voltage switching device with a vacuum interrupter chamber enclosed in an insulating material and containing a fixed contact and a movable contact, while the molded insulating body is open at the bottom in the area of the movable contact or towards the drive rod driving the movable contact, in accordance with the restrictive part of paragraph 1 of the claims.

During operation of the medium voltage switching device, heat is generated due to the transient resistance, which limits the permissible current load in the region of the pole parts. Since the pole parts of the switching device must be enclosed in an insulating material, typically epoxy resin or plastic, heat dissipation resulting from convection is limited.

In this regard, the set permissible current load is limited by the maximum permissible temperature, i.e. such a maximum temperature at which, in particular, there is no damage to the insulating material.

DE 29825094 U1 describes a pole portion of a medium voltage switching device in which a vacuum interrupter chamber is inserted into an epoxy resin housing and is open at the base, i.e. in the lower part. In this case, the greatest electrical transient resistance in the current circuit is created essentially in the lower one, i.e. moving contact. The heat generated there can essentially be dissipated only through thermal conductivity and with difficulty through convection. However, the epoxy insulation material is a poor heat conductor, making it difficult to dissipate.

The objective of the invention is to reduce the heating of the pole parts and, therefore, to provide a higher permissible load at rated current.

This problem is solved in the pole part of the switching medium voltage device according to paragraph 1 of the claims.

Further preferred embodiments of the invention are described in the dependent claims.

At least one ventilation hole is made in the pole part according to the invention in the area of movable contact or at the point of articulation with the drive rod, which extends through the insulation wall, the boundary region between the insulation and the electrical connecting part or through the electrical connecting part of the movable contact. By means of this ventilation opening, heat dissipation occurs by convection directly from the housing of the pole part. In other words, air or gas can flow through the bottom opening, i.e. through the hole in the base of the insulating body of the pole part, and can go out through the ventilation hole located in close proximity to the heat generation area, and heat can thus be removed. As a result, a higher permissible load at rated current is achieved, since no more heat accumulation occurs due to the possibility of heat dissipation to the outside by convection.

Preferably, the ventilation hole extends perpendicular to the axis of movement of the drive pin of the movable contact. The channel length of the ventilation hole, as far as possible, can be as small as possible to ensure the release of heated air or gas.

Preferably, to improve heat transfer to the gas, the surface has an increased roughness or coarse structure.

Preferably, the conductive connection of the movable contact part and the connecting part is a movable electric contact connection formed by a piston electrically and rigidly mechanically connected to the contact rod, and by means of a drilled cylindrical hole made in the connecting part according to the piston / cylinder principle, while the ventilation hole is made immediately below the lower position of the piston when opening. Thus, ventilation or heat dissipation occurs directly in the area of heat storage, therefore, is carried out as efficiently as possible.

Preferably, the vent is made in the region of the outer connecting plate of the connecting part. Thus, the ventilation hole is located in a suitable place, from the point of view of production technology.

Preferably, in the connecting part, the ventilation hole is made through at least one through hollow screw, with which an external contact is fixed in the connecting part, and the hole accommodating at least one such hollow screw is through and connects the outer and inner regions of the pole part to be ventilation. In particular, the use of hollow screws is preferred since no special holes need to be made.

The experiments showed that, despite a possible increase in resistance, for example, by 1 μOhm, the indicated temperature in the same connecting part can be reduced by about 0.5 K. From these experiments, we can conclude that the energy dissipated using this additional measure is about 10 W at a current of about 3000 A. Taking into account the impedance, we can conclude that both on the side of the fixed contact and on the side of the switching contact heat dissipated of approximately 70 watts. Due to the use of drilled holes, the throughput of the pole part can be increased by approximately 14%. The cast portion of the polymer element remains unchanged, and heat dissipates into the environment by convection from the inner region of the pole portion through the connecting portion.

The invention is illustrated in the drawing, which shows in section a pole part.

As shown in figure 1, the chamber 1 of the vacuum interrupter is enclosed in an insulating casing 2 of epoxy resin. In the chamber of the vacuum interrupter, the upper contact is fixed, and the lower contact is movable, while it comes out through a corrugated tube (not shown in detail) and has the ability to move by means of a movable drive rod 3.

To create an electrical connection between the lower movable contact and the outer connecting part 4, a metal conductive connection is made between the movable contact and the metal piston 5. The metal piston 5 can move along the metal conductive cylindrical section 6, which is made in the metal case of the connecting part 4. In this case, the outer The contact pad contact is made using a conductive bus. In this embodiment, a ventilation hole 7 is drilled in the metal housing of the connecting part 4. When the contact is open, it is located below the lowermost position of the piston, i.e. under the piston 5.

The insulating body 2 is open at the bottom. According to the invention, air or gas can flow down and then flow out through the vent, removing heat during operation.

In this case, the ventilation hole 7 can also be made in an epoxy insulating casing 2.

If the ventilation hole 7 is made in a metal case at the bottom of the connecting part 4, then the specified hole (or holes) can be brought out through the hollow screw 8, which is screwed into this hole. Thus, there is no need to drill a special ventilation hole 7, since drilled holes are used, which are made in any case for fastening the external conductive bus with fixing screws. In this case, the holes to be made must be through, rather than usually blind.

Reference Positions:

1 - Vacuum interrupter chamber

2 - Insulating housing

3 - Drive shaft

4 - Connecting part

5 - Piston

6 - Cylindrical section

7 - Ventilation hole

8 - Hollow screws

Claims (5)

1. The pole part of the medium voltage switching device with a vacuum interrupter chamber enclosed in an insulating material and containing fixed and movable contacts, wherein the molded insulating body is open at the bottom in the area of the movable contact or towards the drive rod actuating the movable contact, moreover, in the area of the movable contact or at the point of its articulation with the drive rod (3), at least one ventilation hole (7) is made, passing through the insulation wall (2), the secondary region between the insulation and the electrical connecting part or through the electrical connecting part (4) of the movable contact, characterized in that the ventilation hole (7) is formed in the connecting part (4) by means of at least one through hollow screw (8), with which an external contact is fixed in the connecting part, and the hole containing at least one such hollow screw is through and connects the outer and inner regions of the pole part to be vented. 2. The pole part according to claim 1, characterized in that the ventilation hole (7) extends essentially perpendicular to the axis of movement of the drive rod of the movable contact. 3. The pole part according to claim 1, characterized in that the conductive connection between the movable contact part and the connecting part (4) is a movable electrical contact connection formed by a piston (5), electrically and rigidly mechanically connected to the contact rod, and by a cylindrical hole (6) drilled in the connecting part according to the piston / cylinder construction principle, while the ventilation hole (7) is made directly below the lower position of the piston when opened. 4. The pole part according to claim 1, characterized in that in order to improve heat transfer to the gas, the surface has an increased roughness or rough structure. 5. The pole part according to claim 1, characterized in that the ventilation hole (7) is made in the region of the outer connecting plate of the connecting part (4).