EP-4738420-A1 - GAS-INSULATED HIGH-VOLTAGE ELECTRICAL SWITCHGEAR WITH OVERPRESSURE RELIEF

Abstract

Gas-insulated high-voltage electrical switchgear comprising a gas-insulated enclosure (1), comprising: - a switching means (2) with at least one making/breaking, disconnecting, or grounding function; - a protective element (3) inside a housing (4) contained within a removable fuse holder (5), said housing (4) being mounted between the switching means (2) and at least one shunt busbar (7); and - a plug (9) being part of the same removable fuse holder (5) and that seals the housing (4) by means of an elastic element (10). The switchgear includes an overpressure relief device (8) between the interior space (13) of the housing (4) and the exterior (14) of the enclosure (1). The elastic element (10) of the plug (9) is located where the device (8) is installed.

Inventors

• FERNÁNDEZ URIEN, Andoni
• BARRIO RODRIGUEZ, Sergio
• LARRIETA ZUBIA, JAVIER

Assignees

• Ormazabal Corporate Technology, A.I.E.

Dates

Publication Date

20260506

Application Date

20251029

Claims (6)

1. Gas-insulated high-voltage electrical switchgear comprising a gas-insulated enclosure (1), wherein the enclosure (1) in turn comprises: - at least one switching means (2) with at least one making/breaking - disconnecting - grounding function; - at least one protective element (3) incorporated inside a housing (4) contained in a removable fuse holder (5), said housing (4) being mounted between the switching means (2) and at least one shunt busbar (7); and - a plug (9) forming part of the same removable fuse holder (5) and sealing the housing (4) by means of an elastic element (10) when the protective element (3) is incorporated; characterized in that it comprises an overpressure relief device (8) installed between the inner space (13) of the housing (4) and the outer space (14) of the enclosure (1), such that the overpressure relief device (8) keeps the inner space (13) of the housing (4) airtight under normal operating conditions while allowing the instantaneous evacuation of a flow of gas in case of excess pressure inside the inner space (13) of said housing (4), and wherein the elastic element (10) of the plug (9) is arranged where the overpressure relief device (8) is installed.
2. Gas-insulated high-voltage electrical switchgear according to claim 1, characterized in that the overpressure relief device (8) is installed on the plug (9).
3. Gas-insulated high-voltage electrical switchgear according to claim 2, characterized in that the plug (9) of the removable fuse holder (5) that closes the housing (4) comprises an insulating piece (12) where the overpressure relief device (8) is installed.
4. Gas-insulated high-voltage electrical switchgear according to any of the preceding claims, characterized in that the overpressure relief device (8) is a non-return valve, a vent plug or a vent filter that allows the internal pressure of the housing (4) to be maintained within certain values.
5. Gas-insulated high-voltage electrical switchgear according to any of the preceding claims, characterized in that the protective element (3) is a fuse.
6. Gas-insulated high-voltage electrical switchgear according to any of the preceding claims, characterized in that the switching means (2) is a load break switch or short-circuit current switch.

Description

OBJECT OF THE INVENTION The present invention is applied in the field of electrical power distribution facilities, in particular, it refers to a gas-insulated high-voltage electrical switchgear that has an overpressure relief device integrated into the housing wherein an overload and short-circuit protective element is incorporated. The object of the invention is to keep the housing wherein the protective element is incorporated watertight while allowing the evacuation of excess gas when there is overpressure inside said housing without the protective element having been activated, and thus avoiding the activation of a mechanism for driving a switching means or personal injury when replacing the protective element. BACKGROUND OF THE INVENTION Currently, high-voltage electrical switchgear used in power distribution networks is installed in enclosures that are usually made of metal, called cells. This switchgear includes switching means, such as circuit breakers, that perform the functions of making/breaking, disconnecting, and grounding the installation. Thus, in cases where there is, for example, a fault in the distribution line, an outage due to construction work, maintenance, or load distribution optimization, these switching means can be activated to obtain the desired electrical power distribution, prevent consumers from being left without power, or ensure the protection of people and electrical equipment, such as transformers. In addition to the switching means, electrical switchgear also includes elements for protection against overloads and short circuits, such as fuses. The great advantage of fuses is their rapid response in the event of a short circuit. Consequently, they effectively protect electrical switchgear and electrical equipment, such as distribution transformers, against the dynamic and thermal effects of short circuits. Therefore, an enclosure incorporating electrical switchgear may comprise at least one switching means, such as a load break switch that performs the functions of making/breaking, disconnecting, and grounding, and at least one protective element, such as a fuse. The protective element is installed inside a housing, also known as a fuse holder tube, with the protective element specifically housed in a removable fuse holder base inside said housing. Generally, the switching means is installed between at least one main circuit busbar and the housing that incorporates the protective element, while the protective element housing is installed between the switching means and at least one shunt busbar. In the case of electrical switchgears comprising a switching means and a protective element, such as a series fuse installed downstream of said switching means, there are two types of protection functions: associated fuses and combined fuses. In the first case, that of associated fuses, if one of the fuses blows, the switching means does not open, so the other two phases continue to operate. In contrast, in the second case, that of combined fuses, when any of the fuses blows, the switching means completely cuts off the power supply. In the case of combined fuses, when a fuse blows, it releases a small piece called a striker, which causes the deformation of an elastic element by contact, which in turn triggers a mechanism that activates the switching means so that it opens the circuit, leaving the three phases without power. As mentioned above, part of the electrical switchgear, such as the switching means, main circuit busbars, and shunt busbars, are incorporated into a metal enclosure and insulated in a gas, such as atmospheric air. The enclosure is airtight in cases where the gas used is not atmospheric air, such as sulfur hexafluoride (SF6), dry air, nitrogen, CO2, etc. Regarding the type of gas used, it is worth mentioning that the most commonly used gas in recent years is SF6 gas due to its excellent dielectric properties and, among many other advantages, the fact that it is not toxic to people. However, this gas has a significant environmental impact due to its high greenhouse gas potential (GWP = 22,800). For this reason, in recent years alternative gases have been sought, such as dry air, N2, O2, or CO2, or mixtures of fluoroketones with gases such as CO2, N2, 02, air, or mixtures thereof, that can replace SF6 gas in this type of electrical switchgear. Likewise, the same insulating medium, such as a dielectric gas mentioned above, in some cases also allows the extinction of the electric arc generated between the switch contacts during opening and closing operation. One of the objectives of using a dielectric insulating gas is to reduce the distance between phases, that is, the distance between live parts under voltage, such as the distance between the main circuit bars or between shunt busbars, in order to achieve a more compact enclosure that is insensitive to external or environmental conditions such as pollution or humidity. Therefore, in order to maintain the same dimens