EP1458072B1 - Short-circuit device to be used in low and medium voltage arrangements - Google Patents

Abstract

The short-circuit device (3) has a switch element responding to a release signal for operation of a fault recognition device, received between a pair of current electrodes. The switch element is provided by a triggerable overvoltage protection device responding to a current or voltage pulse and destroyed in the event of a fault. At least one of its electrodes is mechanically pre-stressed for movement in the direction of the other electrode to provide a short-circuit, the electrodes held apart by the overvoltage protection device. An independent claim for an operating method for a short-circuit device is also included.

Description

The invention relates to a short-circuiting device for use in low and medium voltage equipment for property and personal protection, comprising a switching element, which is actuated by a trigger signal of a fault detection device, two the switching element between them receiving electrodes with means for supplying power, said to a circuit with Connections of different potential can be contacted and the switching element is in electrical connection with the electrodes, according to the preamble of patent claim 1.

Various electrical faults can occur in electrical switchgear and distribution systems, which do not lead directly to the response or only to a delayed response of existing overcurrent protection devices. By way of example, arcing arcs may be mentioned here. Similar problems occur in particular with regard to the protection of persons due to operational or faulty potential differences. Such errors can lead to extreme property damage, but also personal injury. To limit the damage in addition to a very quick detection of the error and its rapid shutdown is required.

Various solutions are state-of-the-art for rapid detection of various error cases. Reference is made, for example, to the DE 43 31 992 A1 , which discloses a protected against arcs cell-like switchgear for the distribution of electrical energy. Also in the DE 43 45 170 A1 an arc fault protection device for switchgear is described, where there the actual switching or protective device of a Signal from an AND operation of at least one photosensitive sensor and a light-insensitive sensor is actuated. The actual short-circuiter comprises a coil, the short-circuiter producing a metallic short circuit between the short-circuited parts due to the forces generated by the induction current in cup-shaped metal parts under vacuum. The energy storage source and the coil should be dimensioned so that a metallic short circuit takes place in a time between 0.1 and 2 ms.

In the case of the short-circuiter for use in installations for the distribution of electrical energy according to DE 197 46 815 A1 is provided directly driven by a gas generator short-circuiting element with a short-circuiting piston. The local short-circuiting piston should perform regardless of manufacturing tolerances optimal shock movement and at the same time be transport-secured.

The commonly used protection devices in the low voltage area, such. B. Circuit breakers or fuses, interrupt only high short-circuit currents within a few milliseconds. In the medium voltage range, this ability is almost exclusively limited to fuses. However, such high currents occur only in a part of the possible system errors. In another part of the error, if present, a detection system known per se provides a signal and an upstream circuit breaker is opened. In conventional switches, a time of 20 ms to 100 ms is needed for error detection until shutdown. Such systems are therefore hardly usable for damage limitation. The damage caused to electrical installations is caused by the dynamic action of high currents, by the rapid build-up of high pressures or pressure waves and by the thermal effect of the arc at temperatures of up to 20,000 K.

For effective damage limitation with reduced repair effort, therefore, very short turn-off times, as far as possible under 5 ms, are necessary. Such short turn-off times are therefore necessary because only in this way the height of the fault currents and the duration of action of the arcs can be limited in plants. As known from the prior art, first, the fault currents can be turned off by the existing in the plants switching devices. Second, there is the possibility of the arc fault by a low-resistance connection, z. As a quick short-circuiter shunten until a fault shutdown is done by existing in the system switching devices. In this case, the arc can be brought as a source of thermal destruction in the plants by extinguishing the parallel shunt of the short circuiter.

In the former variant, there is the need to use in addition to a fast fault detection extremely fast switching devices within the plants. This is currently failing due to the high costs and the lack of marketability of such switching devices.

Thus, there is therefore only the possibility of generating a defined short circuit, which limits the damage in the system by extinguishing the arc on the one hand, and on the other hand shortens the period of time for the response of conventional protection devices with short-circuit release.

The short-circuiting device results in very extreme requirements. Thus, in addition to a high insulation value and a high dielectric strength at rest after the signal output extremely low response times, extremely low resistance and high current carrying capacity of up to 100 kA or at impact load up to 220 kA for a period of substantially 100 ms expected. A very low resistance and as low as possible inductance construction are essential for a fast commutation of the current in the short-circuiter and the rapid and safe extinction of the arc fault.

With view on DE 94 19 141 U1 , the DE 197 46 815 A1 as well as the DE 42 35 329 C2 Typical short circuits are known from the prior art. Here, a distinction is made between reusable and single-acting devices. Reusable short circuiters are very expensive and expensive. In the case of single-acting short-circuiters, an explosive charge or a gas generator will generally move towards one another the electrodes used, which understandably special protective measures during manufacture, transportation and use entails.

The generic shorting device according to DE 42 35 329 C2 is particularly suitable for extinguishing arcs in low-voltage switchgear for the distribution of electrical energy. The short-circuiting device consists of at least one switching element which is actuated with a trigger signal of an error detection device, and comprises at least one short-circuiting device. The short-circuiter consists of at least two electrodes receiving the switching element between them and has current-carrying parts or regions. As a result of the current flowing directly in the current-carrying parts both in the switching element and in the short-circuiting device, at least one movable or deformable current-carrying region is pressed against the electrodes, thus producing a metallic short circuit. The current-carrying parts are substantially cylinder jacket or tubular and arranged one inside the other.

Even with this known short-circuit device, the response times are inadequate and it is the overall design arrangement from a manufacturing point of view very expensive.

The state of the art is still on the FR-A-1105378 directed. There, a transversely divided pre-ionizable spark gap according to the preamble of claim 1 is shown. This consists of two parallel-connected units, wherein the branch parallel to the main branch still comprises a series connection with a capacitor. About the spark gap connected in parallel, a discharge of the capacitor take place, with the result that there is a preionization of the main spark gap and this shows a safe ignition behavior.

From the foregoing, it is therefore an object of the invention to provide a rewinding short-circuiting device for use in low and medium voltage equipment for property and personal protection, which is simple and is inexpensive to produce and that is functional without gas generator or pyrotechnic igniter. The short-circuiting device to be created should enable a commutation of the fault current into the short-circuiting device even immediately after the occurrence of the fault, which leads to improved properties in the objective protection of property and personal protection.

The object of the invention is achieved by a short-circuiting device according to the features of claim 1 and by a method for operating such a short-circuiting device as defined in claim 18, wherein the dependent claims represent at least expedient refinements and developments.

Starting from a short-circuiting device, which comprises a switching element which is actuated by a trigger signal of a fault detection device, and wherein two the switching element between them receiving electrodes are provided with means for supplying power, the switching element according to the invention is designed as a triggerable overvoltage protection device, which by a Current or voltage pulse can be brought to the response and destroyed in the event of an error.

At least one of the over-voltage protection device receiving electrodes is under mechanical bias and is movable in the direction of the opposite electrode, the overvoltage protection device forms an electrode spacer, which allows in case of intentional destruction of the electrodes for low-resistance short-circuiting ,

The overvoltage protection device is within the overall arrangement adjacent a space for receiving parts thereof in the event of a short circuit, i. E. intended for targeted destruction. By this clearance blocking the electrode movement is reliably avoided each other.

In one embodiment of the invention, the switching element is a series circuit of a triggerable overvoltage protection device with a device having an adjustable or defined melting integral. In the embodiment of the series connection, only the device with the defined melting integral is destroyed in the event of an error.

The defined melting integral device may be a glass tube fuse, a linear or nonlinear resistor, a varistor, a low melting point metal or metal alloy, a semiconductive or conductive ceramic, or glass or similar material.

The electrically relevant distance between the electrodes in the normal state defines a voltage according to the invention over the response voltage of the switching element, z. As an inserted gas arrester, is located.

The overvoltage protection device can therefore be a gas arrester, a spark gap, a thyristor, a triggerable vacuum switch, a thyratron, a triggerable semiconductor element or a similar assembly.

About the possibility of series and / or parallel connection of several overvoltage protection devices, the electrical parameters can be varied and adapted to the particular case or to the respective system configuration.

To generate the mechanical bias and the electrode movement according to the invention at least one tension or compression spring is provided, which also forms a sufficient resistance in the event of failure destruction of the overvoltage protection device or the switching element. To reduce this destructive pressure, channels or openings may be formed in or between the electrodes.

In a specific embodiment of the short-circuiting device, the electrodes have a respective half-cylinder shape lying opposite the open lateral surfaces, wherein at least one electrode is held spring-biased externally via the cylinder base surface.

In the half-cylinder interior is then the overvoltage protection device, which remains between this and the cylinder inner wall of the free space for receiving parts of the surge protection device in the event of destruction.

The trigger connection is preferably carried out over the cylinder jacket surface and there in turn preferably over that lateral surface of the fixed electrode.

In a further embodiment, one of the electrodes has a cone-shaped inner space and the counterelectrode has a counter-cone or conical shape, wherein the overvoltage protection device is arranged in the bottom region of the electrode with a cone-shaped interior and, in the initial state, the distance between the cone and countercone surfaces is smaller than the distance between the electrodes in the ground area and overvoltage protection device located there is.

A third embodiment is based on an electrode in the form of a pot, in which case the counterelectrode has a plunger mold which dips into the pot.

In the interior of the pot of the corresponding electrode, a circumferential step is provided, which forms the short-circuit region with the stamp surface in case of failure.

Below the grading of the electrode in the form of a pot a receiving space for the triggerable overvoltage protection device is provided.
The device of defined melting potential is in electrical contact between a receptacle in the stamp-shaped electrode on the one hand and with a surface of the overvoltage protection device on the other.

The preferred movable electrode in the form of a stamp is guided by an insulating disk covering the pot mold electrode and kept movable.

In the method according to the invention for operating the proposed short-circuiting device, in the event of a fault, the fault current commutates immediately via the ignited overvoltage protection device from the fault source in the switchgear to the switching element of the short-circuiting device, whereby the total delay time is reduced and the duration of action of arcing faults is reduced. With the destruction of the overvoltage protection device, the electrodes of the short-circuiter come into contact and an irreversible, low-resistance, metallic short circuit is generated.

The movement of the electrodes in the event of a short circuit to each other can be increased or accelerated by an appropriate power supply and a resulting electrodynamic force.

For the purposes of the invention, the integrated overvoltage protection device takes on itself or in cooperation with other, external overvoltage protection devices a system overvoltage protection function and is therefore multivalent.

The invention will be explained below with reference to an embodiment and with the aid of figures.

Fig. 1

einen prinzipiellen Aufbau eines Fehlererfassungssystems in Nieder- und Mittelspannungsanlagen zum Sach- und Personenschutz;

Fig. 2

eine erste Ausführungsform der Erfindung mit einer Kurzschließeinrichtung, welche halbzylinderförmige, gegenüberstehende Elektroden aufweist;

Fig. 3

eine zweite Ausführungsform der Erfindung mit einer Konus- sowie einer Gegenkonuselektrode und

Fig. 4

eine dritte Ausführungsform der Erfindung mit einer Elektrodenkonfiguration, umfassend eine feststehende Topfelektrode und eine bewegliche Stempelelektrode.

Hereby show:

Fig. 1

a basic structure of a fault detection system in low and medium voltage systems for property and personal protection;

Fig. 2

a first embodiment of the invention with a short-circuiting device, which has semicylindrical, opposing electrodes;

Fig. 3

a second embodiment of the invention with a cone and a counter cone electrode and

Fig. 4

a third embodiment of the invention with an electrode configuration comprising a fixed pot electrode and a movable die electrode.

Fig. 1 is based on a known error detection system 1, which is used to detect different abnormal conditions such. As fire, voltage, fault current, pressure, arcs and so on is suitable. The error detection system 1 thus serves to detect an abnormal condition and signal output.

The error detection system 1 supplies a signal to a trigger pulse generating means 2 and further provides a signal, which passes to a reporting device 4. This reporting device 4 can control existing in known systems protective devices.

On the output side, the triggering pulse generating device 2 is connected to a short-circuiting device 3 and supplies a current or voltage pulse, which is matched to the short-circuiting device, to trip it.

However, the trigger pulse generator 2 may also provide pulses for actuating suitable protection devices in the equipment itself. So z. As the external operation of the short-circuit release, in particular a low-voltage switch, with a matched to the device current pulse possible. The same applies to other, in particular with a magnetic field controllable switch, z. B. superconducting switch, vacuum switch with magnetic drive, but also triggerable vacuum switch.

In the first embodiment of the invention according to FIG. 2, a triggerable switching element 7, for. B. in the form of a Gasableiters, a spark gap, a thyristor and so on, which is located between two solid, electrically conductive electrodes 5 and 6. The movable electrode 5 is biased by a compression spring 9 and is in contact with a live busbar.

The fixed electrode 6 carries ground potential.

The two electrodes 5 and 6 are separated from each other by an insulation gap 11. Between or below the switching element 7, which may be a gas arrester in the simplest case, there is a hollow or free space 10th

An ignition electrode 8 or a potential control for the gas discharge tube is isolated connected to the unit for generating a trigger pulse 2 (see Fig. 1).

In the normal state, the gas arrester as a triggerable switching element 7 or a spark gap provided there may, if necessary, limit overvoltages within the scope of the respective intrinsic loadability and thus assume a first protective function.

By selecting the switching element 7 can be at very high isolation values z. B. an almost any operating voltage of the overvoltage protection can be realized.

Due to the performance and the mechanical structure of the overvoltage protection device used, eg. As a gas arrester, the vote between over-voltage protection function and the error case in which the arrester is destroyed, can be made very accurately. This allows a very flexible adaptation of the combination of surge arrester and irreversible short-circuiter for the respective voltage level or according to other other specific system characteristics.

In principle, however, the response value of the gas discharge line should be higher than all voltages occurring in the system during operation.

This means that the dielectric strength of the insulation gap 11 is to be selected clearly above the response voltage of the switching element 7.

When using additional overvoltage protection devices within the system or directly parallel to the intended short circuiter or in addition integrated into the short circuiter (not shown in the figure), care must be taken to ensure that the uninfluenced response of the ignitable by the trigger pulse arrester is higher than the response voltage of the intended for the pure overvoltage protection (further) arrester.

When detecting an error, z. As in arcs, the function of the short-circuiter must be realized very quickly. For this purpose, the switching element is ignited in the event of an error by an ignition pulse, supplied from the trigger pulse generating unit 2. In a current ignition, this pulse can be used directly to destroy the switching element 7 or it Here leads the subsequent current flow through the low-resistance connection of the switching element to its (desired) destruction.

It can thus immediately after the ignition of the switching element 7 already start the commutation of the fault current from the error source to the switching element 7, which is in contrast to known solutions, where this is possible only after the inertial mechanical movement of the contacts.

In this way, the total delay time of the short-circuiter is reduced and reduces the duration of the arc. Another positive effect of this embodiment is that the mechanical motion sequence no longer needs to be extremely accelerated or the mass moved must be minimized since the time to initiation of the short circuit is independent of the movement of the contacts themselves.

Due to the low voltage of the switching element 7, the fault current commutates very quickly into the short-circuiter, even before the start of the movement of the contact or electrode 5 towards the electrode 6 and the mechanical destruction of the switching element 7.

When using a z. B. Gasableiters this decomposes into several items, which are received in the cavity 10. Under the bias of the compression spring 9 moves after the commutation of the fault current has already begun, the electrode 5 to the electrode 6, whereby a quasi-resistance, high current carrying contact is made. This repeated reduction of the electrical resistance promotes the complete commutation of the fault current and ultimately leads to the extinction of unwanted arcs in the system to be protected.

It is within the meaning of the invention that the compression spring 9 is of course to be designed so that it can counteract the pressure that arises in the destruction of the switching element 7.

In the embodiment according to FIG. 3, a large-area, low-resistance contact between the two electrodes 5 and 6 via the cone can very quickly be achieved. or conical surface are produced. Even with a reduced spring force and relatively high pressures by destruction of the switching element 7 a safe short circuit can be achieved. In addition, the power supply in the embodiment of Fig. 3 hardly leads to force components that can counteract a fast low-impedance short circuit.

To dampen the pressure build-up in the destruction of the switching element 7 6 openings or larger cavities may be provided in the bottom region of the electrode.

The guide of the electrode 5 can be realized via a circumferential insulating ring 12.

The contacting of the switching element 7 is isolated by the bottom in the electrode 6 via a terminal. 8

The further embodiment of the invention shown in FIG. 4 is particularly advantageous for large insulation distances and high voltages.

In addition to the embodiments according to FIGS. 2 and 3, a series connection between a surge arrester 7, z. As a gas arrester, and a fuse 13, z. B. a glass tube fuse realized.

After the response of the surge arrester 7, a current flow through the fuse 13, which may also be a varistor, a linear or non-linear resistor.

The fuse 13 itself has a very well adjustable melt integral, via which the interaction with the surge arrester 7 is tuned.

After exceeding the melting integral of the fuse 13, ie in the event of an error, an arc is ignited in the fuse 13 which, although briefly generates a certain arc voltage, but basically leads to the destruction of the fuse housing.

After that, the low-resistance connection between the electrodes 5 and 6 is produced. In this embodiment, the destruction of the actual switching element, i. a z. B. used surge arrester 7, are omitted, resulting in a greater latitude for its design and construction.

Instead of the fuse with housing, other materials with relatively high mechanical strength, but a small, relatively small melting integral can be used, such as special low-melting metals or alloys.

The Topfformelektrode 6 of FIG. 4 has a gradation to 14, which forms the short-circuit region with the punch surface 15 of the opposite electrode 5 in case of failure.

Below the grading 14, a receiving space A for the triggerable overvoltage protection device 7 is present. The receiving space A also serves to accommodate parts of the destroyed in the event of an error device 13, without the movement of the punch electrode 5 is hampered towards the cup-shaped electrode 6 with the desired coming into contact.

LIST OF REFERENCE NUMBERS

1

Fault detection system

2

Trigger pulse generator

3

Earthing

4

signaling device

5

Stamp form electrode

6

Cup form electrode

7

switching element

8th

Connection

9

compression spring

10

Hollow or free space

11

isolation gap

12

insulation ring

13

fuse

14

gradation

15

stamp surface

A

accommodation space

Claims (20)

1. A short-circuit device to be used in low and medium voltage systems for the protection of property and persons, comprising a switching element (7) which is actuated by a trigger signal of a fault detection device (1), two electrodes (5; 6) with power supply means accommodating the switching element (7) between them, wherein the same can be contacted with a circuit having different potential terminals and the switching element (8) is electrically connected to the electrodes (5; 6),
   characterized in that
   the switching element (7) is a triggerable overvoltage protection device which can be put into operation by a current or voltage pulse and is destructible in the event of a fault,
   at least one of the electrodes (5) accommodating the overvoltage protection device is mechanically prestressed and movable toward the opposite electrode (6), wherein the overvoltage protection device forms an electrode spacer allowing, in the event of the destruction, a contacting of the electrodes to produce a short circuit, and a free space (10) for receiving parts in the event of a short circuit fault is provided adjacent to the overvoltage protection device.
2. The short-circuit device according to claim 1,
   characterized in that
   the switching element (7) is a series connection of a triggerable overvoltage protection device and a device (13) with an adjustable or defined fuse integral.
3. The short-circuit device according to claim 2,
   characterized in that
   in the event of a fault merely the device (13) with the defined fuse integral is destroyed in the series connection.
4. The short-circuit device according to claim 2 or 3,
   characterized in that
   the device (13) is a glass-tube fuse, a linear or non-linear resistor, a varistor, a low-melting metal or a metal alloy, a semiconducting or conducting ceramic or glass, or the like.
5. The short-circuit device according to one of the preceding claims,
   characterized in that
   the electrically relevant space between the electrodes (5; 6) defines a voltage which is above the operate voltage of the switching element.
6. The short-circuit device according to one of the preceding claims,
   characterized in that
   the overvoltage protection device (7) is a gas arrester, a spark gap, a thyristor, a triggerable vacuum switch, a thyratron, a triggerable semiconductor component, or the like.
7. The short-circuit device according to one of the preceding claims,
   characterized in that
   several overvoltage protection devices (7) connected serially and/or in parallel are provided.
8. The short-circuit device according to one of the preceding claims,
   characterized in that
   at least one tension or compression spring (9) is provided to generate the mechanical prestress and the relative movement of the electrodes.
9. The short-circuit device according to one of the preceding claims,
   characterized in that
   the electrodes (5; 6) each have a semi-cylindrical shape and are provided opposite each other with their open circumferential surfaces, wherein at least one electrode (5) is externally prestressed via the cylinder base surface.
10. The short-circuit device according to claim 9,
    characterized in that
    the overvoltage protection device (7) is disposed in the interior space of the semi-cylinder and the free space (10) remains between the same and the inner wall of the cylinder.
11. The short-circuit device according to one of claims 9 or 10,
    characterized in that
    the trigger terminal (8) is embodied by the circumferential surface of the cylinder, preferably of the stationary electrode (6).
12. The short-circuit device according to one of claims 1 to 8,
    characterized in that
    one of the electrodes (5; 6) has a conical interior space and the counter-electrode has a counter-conical or cone shape, wherein the overvoltage protection device (7) is disposed in the bottom area of the electrode (6) with the conical interior space and the space between the conical and the counter-conical surface in the initial state is smaller than the space of the electrodes in the bottom area with the overvoltage protection device (7) disposed therein.
13. The short-circuit device according to one of claims 2 to 4,
    characterized in that
    one of the electrodes is pot-shaped (6) and the counter-electrode has the shape of a plunger (5) which plunges into the pot.
14. The short-circuit device according to claim 13,
    characterized in that
    a circumferential stepping (14) is provided inside the pot, which forms together with the plunger surface (15) the short-circuit region in the event of a fault.
15. The short-circuit device according to claim 14,
    characterized in that
    a receiving space (A) for the triggerable overvoltage protection device (7) and for parts of the device destroyed in the event of a fault is provided underneath the stepping (14).
16. The short-circuit device according to claim 15,
    characterized in that
    the device (13) with the defined fuse potential is in electrical contact with a receptacle in the plunger-shaped electrode (5) on the one hand and with a surface of the overvoltage protection device (7) on the other hand.
17. The short-circuit device according to one of claims 14 to 15,
    characterized in that
    the preferably mobile plunger-shaped electrode (5) is guided by an insulating disc (12) which covers the pot-shaped electrode (6).
18. A method for operating a short-circuit device according to one or more of the preceding claims,
    characterized in that
    in the event of a fault, the fault current immediately commutates via the triggered overvoltage protection device (7) from the fault source in the switching system to the switching element so as to reduce the total delay time and shorten the impact time of arcing faults, wherein the electrodes (5; 6) are brought into contact and generate an irreversible low-impedance metallic short circuit as the overvoltage protection device is destroyed.
19. The method according to claim 18,
    characterized in that
    the movement of the electrodes (5; 6) toward each other in the event of a short circuit is increased by the action of electrodynamic forces.
20. The method according to claim 18 or 19,
    characterized in that
    the integrated overvoltage protection device (7) assumes by itself or in cooperation with additional external overvoltage protection devices a system overvoltage protection function.

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