EP-4736207-A1 - SWITCHGEAR PLATE

EP4736207A1EP 4736207 A1EP4736207 A1EP 4736207A1EP-4736207-A1

Abstract

A switchgear comprising a first contact and a second contact configured to form an electrical conducting path through the switchgear, wherein the second contact can be moved relative to the first contact, a first arc runner electrically connected to the first contact, a second arc runner electrically connected to the second contact when the first contact and the second contact are separated, an arc extinguishing chamber arranged at least partially in a space between the first arc runner and the second arc runner, an arc guiding plate having a first surface and a second surface opposite to the first surface, wherein the arc guiding plate is formed in a single piece from a non-conductive material, a pre-chamber area disposed between the arc extinguishing chamber and the first and second contacts, wherein the pre-chamber area is at least partially defined by the first and second arc runners and the first surface of the arc guiding plate, wherein the first arc runner and the second arc runner are at least partially disposed on the first surface of the arc guiding plate, wherein the first surface of the arc guiding plate comprises a channel having a first end and a second end, wherein the first and second ends of the channel are open.

Inventors

Spritzendorfer, Bernd
DORNHACKL, Dominik
ERTL, MICHAEL
JANSENBERGER, Thomas

Assignees

Eaton Intelligent Power Limited

Dates

Publication Date: 20260506
Application Date: 20240623

Claims (1)

Claims 1. A switchgear comprising: a first contact (102) and a second contact (103) configured to form an electrical conducting path through the switchgear, wherein the second contact can be moved relative to the first contact; a first arc runner (104) electrically connected to the first contact; a second arc runner (105) electrically connected to the second contact when the first contact and the second contact are separated; an arc extinguishing chamber (107) arranged at least partially in a space between the first arc runner and the second arc runner; an arc guiding plate (109) having a first surface (109a) and a second surface (109b) opposite to the first surface, wherein the arc guiding plate is formed in a single piece from a non-conductive material; a pre-chamber area (108) disposed between the arc extinguishing chamber and the first and second contacts, wherein the pre-chamber area is at least partially defined by the first and second arc runners and the first surface of the arc guiding plate; wherein the first arc runner and the second arc runner are at least partially disposed on the first surface of the arc guiding plate; wherein the first surface of the arc guiding plate comprises a channel (110) having a first end (110a) and a second end (110g), wherein the first and second ends of the channel are open. 2. The switchgear according to claim 1, wherein the second surface of the arc guiding plate does not comprise a channel, optionally wherein the second surface of the arc guiding plate is flat. 3. The switchgear according to claim 1 or 2, wherein the arc guiding plate comprises a first edge (111a) facing towards the arc extinguishing chamber and the first end (110a) of the channel meets the first edge of the arc guiding plate. 4. The switchgear according to any of the preceding claims, wherein the arc guiding plate comprises a second edge (mb) facing towards a region of the switchgear in which the first and second contacts are at least partially disposed, and the second end of the channel meets the second edge of the arc guiding plate. 5. The switchgear according to claim 4, wherein a position at which the second end of the channel meets the second edge of the arc guiding plate is aligned with a first gap (Gi) formed between the first and second contacts when the first and second contacts are separated. 6. The switchgear according to any of the preceding claims, wherein the channel comprises a first, second, and third straight portion (110b, nod, nof) and a first and second curved portion (110c, noe), and wherein the first curved portion connects the first and second straight portions and the second curved portion connects the second and third straight portions. 7. The switchgear according to any of the preceding claims, wherein the first arc runner does not overlap the channel when the switchgear is viewed in a direction perpendicular to the first surface of the arc guiding plate. 8. The switchgear according to any one of the preceding claims, wherein the arc guiding plate comprises a third edge (111c) facing towards the second arc runner and the channel does not meet the third edge of the arc guiding plate. . The switchgear according to claim 8, wherein there is a second gap (G2) between at least a portion of the third edge of the arc guiding plate and the second arc runner when the switchgear is viewed in a direction perpendicular to the first surface of the arc guiding plate. 10. The switchgear according to claim 8 or 9, wherein the third edge of the arc guiding plate comprises a tapered portion (112). 11. The switchgear according to claim 10, wherein the second arc runner is at least partially disposed on the tapered portion of the third edge of the arc guiding plate. 12. The switchgear according to any of the preceding claims, wherein the first and second surfaces of the arc guiding plate comprises one or more through holes 13- The switchgear according to any of the preceding claims, wherein the arc guiding plate is made of a plastic material. 14. The switchgear according to any of the preceding claims, wherein the arc guiding plate is a first arc guiding plate and the switchgear further comprises a second arc guiding plate (119), and wherein the first arc runner and the second arc runner are at least partially disposed between the first arc guiding plate and the second arc guiding plate to form the pre-chamber area. 15. The switchgear according to claim 14, wherein the second arc guiding plate is identical to the first arc guiding plate, and wherein the first surface of the first arc guiding plate and the second surface of the second arc guiding plate (119b) form the pre-chamber area. 16. An arc guiding plate, formed in a single piece from a non-conductive material, the plate comprising: a first surface, and a second surface opposite to the first surface, wherein the first surface of the plate comprises a channel having a first end and a second end, and the first and second ends of the channel are open.

Description

Switchgear Plate Field This relates to protecting a switchgear from electrical arcs. In particular, this relates to an arc guiding plate for protecting a switchgear. Background Electrical circuits may be damaged by larger than normal currents flowing through the circuit (due to, for example, short circuits or overloads). One approach to prevent damage to an electrical circuit is to use a switchgear to interrupt the flow of large currents by separating electrical contacts within the circuit (i.e. by opening the circuit). For example, an MCB (miniature circuit breaker) of the switchgear protects the current line in case of an overload or short circuit by interrupting the faulty circuit and thus reducing the otherwise negative impact of the thermal stress from large currents on the e.g., switchgears plastic insulation, and the components/circuit environment. In case of a short-circuit, the increasing current on the line triggers a magnetic operated actuator, which interacts with the MCB’s mechanism to open the electrical contacts. Any suitable circuit breaker can be used. Separating electrical contacts carrying a large electric current cause an electric arc to form between the contacts. Opening of electrical contacts under load (high current & voltage) is always associated with the generation of an electric arc (between the separating contacts). The arc originates from an initial rupture of a small liquid metal “bridge” between the opening contacts (formed due to local overheating of the contact material when the current density increases as the cross-section of the contact area goes to zero when the contacts open). As gas passes through the rupture, it is ionized, generating a plasma. In other words, the arc between the two contacts is a plasma state (up to 10K in temperature). The plasma can cause damage to, and contamination of, components in the switchgear. For example, the high temperatures when an arc is formed or generated may melt portions of the contacts, and the contact surface is further degraded or eroded by the arc itself the longer the arc is sustained. In addition to damage to the contact, the melted material may be transferred to other components of the switchgear. System contamination and damage can reduce the minimum dielectric strength of the switchgear, which can make it easier for arcs to form and could lead to a flashover (even when the contacts are separate). Therefore, the arc has to move away from the contact area to avoid degradation of the contact’s surface (due to erosion by the arc) and other damage to the circuit breaker. To increase safety and durability, switchgears typically comprise an arc extinguishing chamber. Switchgears are configured to drive the ionised gas, e.g. the plasma/electrical arc, towards the arc extinguishing chamber. Various arc extinguishing methods can be used within the chamber, as required by the specific application. In order to drive the arc towards the arc extinguishing chamber, the current path within the circuit breaker (for example, the MCB) of the switchgear can be designed to establish a current loop, with the arc being part of the loop. Magnetic forces (Lorentz force) created by the current loop and acting on the arc will move/ drive the arc away from the contacts. In particular, arc runners are used to take over the arc foot-points from the fixed and movable contacts, respectively, and lead the arc away from the contacts towards the arc extinguishing chamber. Once the arc is formed the current continues to rise, increasing the energy of the arc and thereby increasing the plasma pressure. Therefore, in addition to the magnetic or Lorentz forces driving the arc, the movement of the arc is affected by gas dynamics within the switchgear (i.e. by the interaction between the plasma and other gases). The heat transferred to the surroundings by the electric arc increases the temperature and thus the pressure of the gases within the switchgear. In particular, the high-pressure gas created by the high temperature at the point of formation of the arc leads to a shockwave travelling (with speed of sound) in both directions from the point of arc generation. Reflections due to surfaces or obstacles in the switchgear (e.g. narrowing due to the arc extinguishing chamber components) can direct this shockwave back to the moving arc column and retard its movement to the arc extinguishing chamber. In other words, these high-pressure gases can act to slow the arc down on its way to the arc extinguishing chamber, unless they are removed. AU676934B2 discloses apertures which allow these gases to flow away from the area, reducing the gas pressure in the vicinity of the front of the arc. However, the generated gases can also be used to drive the arc away from the opening contacts and towards the arc extinguishing chamber. For example, DE 102017204942 Al discloses a switchgear configured to route the high- pressure gases generated behind the arc, increasing pressure b