NL2022014A - Device for reducing fault arcs in an electric distribution unit - Google Patents

Abstract

In a device (1) for reducing fault arcs in an electric distribution unit, comprising a housing (2), a first busbar (3) and a second busbar (4), wherein the first busbar (3) has a first electric connection point (5) and the second busbar (4) has a second electric connection point (6), wherein the first busbar (3) is positioned at a distance from the second busbar (4), it is proposed that, within the housing (2), at a predetermined burn—up point (7) for a fault arc, a breakdown voltage value between the first busbar (3) and the second busbar (4) is lowest, and that the housing (2) is open.

Description

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© 2022014 © A PATENT APPLICATION © Application number: 2022014 @ Application submitted: November 16, 2018 © Int. Cl .:

H02B 1/20 (2019.01) H02H 9/06 (2019.01) © Application registered:

May 2019 © Request published:

May 2019 © Applicant (s):

Eaton Intelligent Power Limited in 4 Dublin, Ireland, IE.

© Inventor (s):

Georg Reubergerte Schweiggers (AT). Thomas Gattringer in Weitra (AT).

© Authorized representative:

ir. B.J. 't Jong in Enschede.

© Device for reducing fault arcs in an electric distribution unit © In a device (1) for reducing fault arcs in an electric distribution unit, including a housing (2), a first busbar (3) and a second busbar (4), the first busbar (3) has a first electric connection point (5) and the second busbar (4) has a second electric connection point (6), the first busbar (3) is positioned at a distance from the second busbar (4) ), it is proposed that, within the housing (2), at a predetermined burn-up point (7) for a fault arc, a breakdown voltage value between the first busbar (3) and the second busbar (4) is lowest, and that the housing (2) is open.

NL A 2022014

This publication corresponds to the documents originally submitted.

Device for reducing fault arcs in an electric distribution unit

The present invention refers to a device for reducing fault arcs in an electric distribution unit according to the preamble of claim 1.

Fault arcs occurring in an electric distribution unit, such as an electric cabinet, represent a great danger due to the sudden and unpredicted high power generated, which may have explosive effects. On one hand, long inactivity periods and costly maintenance may occur due to the damage caused by fault arcs. Moreover, fault arcs often occur in case or unproperly executed maintenance work, as a result or which operators are frequently injured.

The generation of a fault arc inside an electric distribution unit may have various causes. Frequently, a tool or other loose object left in the distribution unit may cause fault arcs when the distribution unit is switched on. A further possibility of generating a fault arc is when, at switch-off or a low-voltage power switch, ionized air is expelled from the electric distribution unit and reduces the breakdown voltage between the phases. Since induced voltage peaks may also occur when switching off a low voltage power switch, a fault arc may be generated between the phases due to the combination of these two effects.

Devices for reducing fault arcs are known which detect the occurrence of a fault arc and short circuit the phases of the electric distribution unit when a fault arc is detected so that energy is removed from the fault arc.

Such devices, which have to short circuit the phases as fast as possible, are very complex and expensive to produce. Also, the use of electronic components is required for a fast switch-off.

The object of the invention is thus to provide a device for reducing fault arcs or the aforementioned type, by means of which said drawbacks may be prevented, and which may reduce the damage caused by the occurrence of a fault arc while being very simple to produce .

This object has been achieved according to the invention by the features of claim 1.

The advantage is obtained is that a predetermined position within the electric distribution unit may be provided for the fault arc, ie the burn-up point in the device, in which the fault arc may burn in a controllable environment until the electric distribution unit is switched off or the fault arc self-extinguishes. This is achieved by the fact that a predetermined point having the lowest breakdown voltage is formed between the first busbar and the second busbar, at which point the fault arc may be either generated in presence of ionized gases or may be captured in case it is generated at another position within the electric distribution unit. Through the open housing, on one hand, ionized gas may enter and / or a fault arc moving along the phases of the electric distribution unit may be led from the phases of the electric distribution unit to the burn-up point within the housing. Thus, the destructive effects of a fault arc may be controlled, and equipment and people may be protected against damages without the use of fault-prone components such as detectors.

The dependent claims refer to further advantageous of the invention.

Reference is hereby expressly made to the wording of claims, Beyond the claims are considered to be reproduced verbatim and inserted at this point by way or reference into the description.

The invention is now explained in further detail, with reference to the annexed drawings, which only illustratively represent a preferred embodiment. In particular:

FIG. 1 shows a preferred embodiment of the device in an axonometric view;

FIG. 2 shows the preferred embodiment of the device in an exploded view; and

FIG. 3 shows a portion of the preferred embodiment or the device in a plan view.

FIGs. 1 to 3 show at least portions of a preferred embodiment of a device 1 for reducing fault arcs within an electric distribution unit, including a housing 2, a first busbar 3 and a second busbar 4, where the first busbar 3 has a first electric connection point 5 and the second busbar 4 has a second electric connection point 6, where the first busbar 3 is positioned at a distance from the second busbar 4.

The device 1 is provided for reducing fault arcs within an electric distribution unit. The reduction occurs in an uncontrolled propagation of the fault arc is prevented, and the fault arc may release its energy, which has been reduced by the device, at a predetermined point. A fault arc is an unwanted electric arc. The device 1 comprises a housing 2, which housing 2 preferably has an upper housing part 13 and a lower housing part 14, which are releasably fixed to each other.

The device 1 also has a first busbar 3 and a second busbar 4. In this context, busbars 3, 4, 10 are considered to be uninsulated and solid conductors, which are suitable for high currents, such as those used in busbar distribution systems within low voltage distribution units. The first busbar 3 has a first electric connection point 5, which is provided for connection to a first phase of the electric distribution unit. The second bus bar 5 has a second connection point 6, which is provided for connection to a second phase of the electric distribution unit.

The first busbar 3 is also positioned at a distance from the second busbar 4, so that the first busbar 3 is not electrically contacting the second busbar 4.

Within the housing 2, at a predetermined burn-up point 7 for a fault arc, the breakdown voltage between the first busbar 3 and the second busbar 4 is lowest and the housing 2 is open.

The first busbar 3 and the second busbar 4 are thus formed in a way that at a predetermined point, which is called the burn-up point 7 for a fault arc, the breakdown voltage between the first busbar 3 and the second busbar 4 has the lowest value. The breakdown voltage is the voltage required for generating the electric arc. In this case, the presence of ionized air in particular is assumed in order to calculate the breakdown voltage. The breakdown voltage is primarily determined by the geometry of the first busbar 3 and of the second busbar 4, in particular by the minimum distance between the first busbar 3 and the second busbar 4. The burn-up point 7 for the fault arc may thus be in particular a restriction point where the distance between the first busbar 3 and the second busbar 4 is at a minimum. Thus, the fault arc, if present, essentially burns only at the burn-up point 7 without leaving the device 1.

The fact that the breakdown voltage between the first busbar 3 and the second busbar 4 is smallest at the burn-up point 7 for a fault arc means in particular that it is at a minimum with respect to the breakdown voltage between the first busbar 3 and the second busbar 4 both separately from the burn-up point 7 as well as in particular with respect to an expected breakdown voltage or the electric distribution unit intended to be used.

The fact that the housing 2 is open means that the housing 2 has entry opening 15 for gases and / or fault arcs which are not closed. Thus, ionized gases, which may be generated in particular in case of a faulty switch-off process or a power switch and / or fault arcs may be led from outside into the housing 2 and thus also to the burn-up point 7. A faulty switch-off process is considered in this case to be a switch-off process or the power switch in which an unusually high discharge or ionized gases occurs.

The advantage thus obtained is that a predetermined point may be provided for a fault arc within the electric distribution unit, ie the burn-up point 7 within the device 1, in which the fault arc may burn in a controllable environment until the electric distribution unit is switched off or a self-extinction or the fault arc occurs. This is achieved by the fact that a predetermined point having the lowest breakdown voltage is formed between the first busbar and the second busbar, at which point the fault arc may be either generated in presence of ionized gases or may be captured in case it is generated at another position within the electric distribution unit. By way of the open housing 2, ionized gas may enter and / or a fault arc moving along the phases of the electric distribution unit may be led from the phases of the electric distribution unit to the burn-up point 7 within the housing 2. Thus the destructive effects of a fault arc may be controlled, and equipment and people may be easily protected from damages or injuries without the use of fault-prone components, such as detectors.

Preferably, it can be provided that the device 1 comprises a third busbar 10 having a third electric connection point 11, that the third busbar 10 is positioned at a distance from the first busbar 3 and the second busbar 4, that, within the housing 2 at a further predetermined burn-up point 12 for a fault arc, the breakdown voltage between the third busbar 10 and the second busbar 4 is lowest, in particular, the further burn-up point 12 is essentially formed in the same way as the burn-up point 7 between the first busbar 3 and the second busbar 4. As a result, the device 1 may be suitable for an electric distribution unit having three phases.

The connection points 5, 6, 11 may be positioned outside of the housing 2. The busbars 3, 4, 10 may then lead from the connection points 5, 6, 11 into the housing.

In order to form the connection points 5, 6, 11, the bus bars 3, 4, 10 may be provided at an end with slots, through which a screw connection with the phases may be provided.

The busbars 3, 4, 10 may preferably be made primarily or copper.

Further preferably, an electric distribution unit, in particular an electric cabinet including the device 1 for reducing fault arcs, is provided within an electric distribution unit. The electric distribution unit may have particular phases, which are also composed of bus bars. Such electric distribution units are often used in low voltage applications in a main distribution facility or in industrial plants.

The device may be exclusively connected to the phases, i.e. it may be an additional earth or PEN conductor. In particular, it is preferred that the electric distribution unit has a power switch, and that the device 1 for reducing fault arcs is positioned within an electric distribution unit in the region of the power switch, in particular in an unprotected path or the power switch . The power switch may in particular be an open power switch and / or a low voltage power switch. In such power switches, the electric arc generated during a switch-off process is blown out by means of air through an opening so that ionized air is released in the region of the power switch. The device 1 may be connected to the same phases of the power switch in this case. The arrangement of the device 1 in the area of the power switch means in this context that the device 1 is near the power switch. The device 1 may be positioned in particular in the unprotected path of the power switch.

In this case, the unprotected path of the power switch is the portion of the electric distribution unit at the power switch which is under voltage even when the power switch is switched off. Specifically, if the power switch is blows on a downstream path, which is therefore protected, this deenergized path is not endangered due to the switch-off process or the power switch, but the unprotected path is upstream or the power switch. The fault arc may be burned off in a controlled way until further protection devices de-energize this portion as well.

The device 1 may be composed in particular or a module. In this case, the device 1 is already provided as a finished unit and only a connection with the phases of the electric distribution unit is required. A modular device 1 is advantageous in that it may be rapidly mounted or replaced. This is particularly advantageous since the device 1 has been replaced after the occurrence of a fault arc.

Alternatively, the device 1 may be directly mounted into the electric distribution unit.

In particular, it is advantageous that the housing 2 has a high-temperature-resistant and electrically insulating cladding part 8. The cladding part 8 has both the task of preventing, for as long as possible, the destruction of the housing 2 by the fault arc and the task of insulating the inside of the housing 2 from the outside. The cladding part 8 may also have the function of absorbing a portion of the thermal energy which is released by the fault arc and thus or cooling down the fault arc. The cladding part 8 may also be in particular composed of a variety of parts.

The cladding part 8 may in particular be composed of ceramics or stone, preferably fireclay.

Preferably, the cladding part 8 may in particular be made or a duroplastic material which is preferably reinforced by fibers, such as in particular Durostone. Thus, the cladding part 8 may additionally better resist the pressure wave caused by the electric arc.

According to the preferred embodiment of the device

1, the housing 2 has an additional external cover 17 surrounding the high-temperature-resistant and electrically insulating cladding part 8.

Alternatively, the housing 2 may only be composed of the cladding part 8.

In particular it is preferred that the first busbar and / or the second busbar 4 have an electrode 9 at the burnup point 7. The electrode 9 may in particular be part of the busbar 3, 4, 10 which is made of a material that is different from the rest of the busbar 3, 4, 10. As a result, the portion of the busbar 3, 4, 10 which is subject to the highest stress due to the fault arc may be better protected against those stresses.

It may preferably be provided that the electrode 9 is made of a metal or a metal alloy having a melting point higher than l, 200 ° C.

It may also be preferably provided that the electrode has a convex shape. Due to the convex shape, a defined and larger contact surface for the fault arc may be provided, thus reducing wear. Moreover, due to the convex shape, the electric field strength is increased, as a result of which the breakdown voltage may be reduced. The convex shape may have a radius of essentially 50 mm.

Preferably, the electrode 9 is formed by a head of a carriage bolt 16. Thus, the electrode 9 may be particularly easy to form.

A side opposite to the electrode 9 may be preferably formed by a counter-electrode 20.

The counter-electrode 20 may also have a convex shape.

The minimum distance between the electrode 9 and the counter-electrode 20 is preferably kept as small as possible in order to still comply with the required minimum leakage path and air gap requirements.

A minimum distance between the electrode 9 and the counter-electrode 20 may in particular be between 10 mm and 15 mm, preferably essentially 11.5 mm.

Moreover, the electrode 9 may have an electric conductivity lower than 10 ^Λ 7 A / (Vm). This electric conductivity is thus narrower than copper, which is about 6 * 10 ^Λ 7 A / (Vm). Due to the reduced electric conductivity, the current value of the fault arc is reduced, wear wear is reduced.

Particularly advantageous is the case when the electrode 9 is made of steel, in particular stainless steel. Steel, in particular stainless steel, is particularly suitable since the wear on it caused by the fault arc is lower due to its high mechanical strength, thermal resistance and relatively low electric conductivity.

Particularly preferably, it can be provided that a fault arc propagation region free from built-in components and extending from the connection points 5, 6 to the burn-up point 7 arranged between the first busbar 3 and the second busbar

4. The fault arc propagation region is in this case a free space extending from the connection points 5, 6 to the burn-up point 7, along which a fault arc generated outside of the device 1 may propagate, unhindered, to the burn up point 7. In this case, it can be provided in particular, at the position on the housing 2 where the busbars 3, 4, 10 is penetrate from outside into the housing 2, the space between the busbars 3, 4, 10 is not enclosed by the housing 2. Thus, entry opening 15, which are not closed, may be formed between the busbars 3, 4, 10. Thus, a fault arc which was initially propagating in the electric distribution unit may be led to the burn -up point, where it is then retained.

Preferably, the housing 2 may be provided with a slot in the region of the connection points 5, 6, 11, through which the busbars 3, 4, 10 pass. The slot may in particular be formed between the housing upper part 13 and the housing lower part 14.

First parts 18 of the busbars 3, 4, 10 may have a plate-like shape, and in particular they may be placed in a plane, preferably preferably the second busbar 4 is positioned between the first busbar 3 and the third busbar 10.

The first busbar 3 and the third busbar 10 may preferably be essentially formed by the first part 18 only.

The second busbar 4 may have a second part 19, which protrudes from the plane and extends over the first busbar 3 and the third busbar 10. The electrodes 9 may be positioned on the second part 19. Thus, the burn-up points 7 , 12 may be readily produced.

A reliable distancing between the bus bars 3, 4, 10 may be obtained by insulating distance pieces 21.

Moreover, an electrically insulating separation piece having an aperture may be positioned at the burn-up point 7 between the first busbar 3 and the second busbar 4. The separation piece is not shown in Figs. 1 to 3. The fault arc may burn in the aperture, the separation piece prevents a lateral propagation of the fault arc, thus limiting its power.

Moreover, the aperture in the separation piece may be narrower than the electrode 9, in order to prevent an unwanted collision between the electrode 9 and the counterelectrode 20.

The aperture in the separation piece may have an open edge in particular. Thus, the fault arc may move from outside into the aperture.

Alternatively, the aperture in the separation piece may be closed, i.e. only represent a hole. This hinders the movement of the fault arc from outside into the burn-up point 7. However, the fault arc may still form in the burn-up point 7, the closed aperture reliably holds the fault arc at the burn-up point 7 .

Claims (11)

Conclusions Device (1} for reducing spark discharge in an electrical distribution unit, comprising 5, a housing (2) _at a first busbar (3) and a second busbar (4), wherein the first bus bar (3) has a first electrical connection terminal (5), and. the second bus bar (4) has a second electrical connection point (6), the first bus bar (3) being positioned at a distance from the second bus bar (4), Characterized in that in the housing (2), at a predetermined burn-out point (7) for a spark discharge, a breakdown voltage value between the first busbar (3) and the second busbar (4) is the lowest, and that the housing (2) is open 15. The device (1) according to claim 1, characterized in that the housing (2) has a high temperature resistant and electrically insulating covering part (8). The device (1) according to claim 1 or 2, with Characterized in that the first busbar (3) and / or the second busbar (4) has an electrode (9) at the burn-up point (7), The device (1) according to claim 3, characterized in that the electrode (9) has a convex shape. The device (1) according to claim. 3 or 4, with Characterized in that the electrode (9) has a value lower than 10 ^? A / (7 m). 6. The device (1) according to one. of claims 3 to 5, characterized in that the electrode (9j is made of steel, in particular stainless steel). 30: 7, The device (1) according to one of the claims 1 - 6, characterized in that a spark discharge spreading region, which is free of built-in parts, and which extends from the connection pits (5, 6) until the burn-up point - (7) is positioned between the first busbar (3) er; da second bus bar (4). The device (1) according to one of the claims 1 7, characterized in that an electrically insulating The separating part with an opening is positioned at the burn-up point (7) between the first bus bar (3) and the second bus bar (4). The device (1) according to one of the claims 1 - 8, characterized in that - the device (1). a third bus bar 10 (10) has -with a third electrical connection point (.11), that the third busbar (lp.) Is positioned at a distance from the first busbar (3) and the second busbar (4), which, in the housing ( 2), the breakdown voltage between the third busbar (10) and the second busbar (4) is lowest at a predetermined Further burn-out point (12) for a spark discharge, in particular the further burn-out point (12) being formed substantially in the same way as the burn-up point (7) between the first bus bar (3) and the second bus bar (4). 10. An electrical distribution unit, in particular 20 an electrical box, comprising a device (1) for reducing spark discharge in an electrical distribution unit according to one of the following. claims 1 - 9 " The electrical distribution unit according to claim 10, characterized in that the electrical distribution unit is a 25 has a power switch, and the device (1) for reducing spark discharge in an electrical distribution unit. is positioned in the area of the power switch, particularly within an unprotected path of the power switch.