WO2015028586A1

WO2015028586A1 - Fuse element for an overvoltage protection device

Info

Publication number: WO2015028586A1
Application number: PCT/EP2014/068333
Authority: WO
Inventors: Jan- Erik SCHMUTZ; Markus Puschmann; Thomas Meyer
Original assignee: Phoenix Contact Gmbh & Co.Kg
Priority date: 2013-08-30
Filing date: 2014-08-29
Publication date: 2015-03-05
Also published as: DE102013217320A1; CN105556636A

Abstract

The invention relates to a fuse element for an overvoltage protection device (ÜSE). The fuse device has a multi-part housing, which has at least a first housing part and a second housing part, wherein the first housing part and the second housing part engage with each other in a form-closed manner at least in some sections, such that a pressure-resistant interior is formed. The interior has a continuous conductor, wherein the first housing part and the second housing part can be moved in relation to each other. In a first state, the first housing part and the second housing part are under pre-load, wherein mutual movement of the housing parts is prevented by a retaining mechanism, wherein the continuous conductor provides an electrically conductive connection. In a second state, the pre-load F has led to a movement of the housing parts in relation to each other, wherein the continuous conductor is interrupted. The continuous electrical conductor is dimensioned in such a way that the maximum pulse current of the overvoltage protection device (ÜSE) to be protected can be nondestructively conducted in the first state. The retaining mechanism can be released by external triggering, wherein the triggering is effected by means of a measured variable with regard to the overvoltage protection device (ÜSE) to be protected.

Description

Fuse element for an overvoltage protection device

Phoenix Contact GmbH & Co. KG, Blomberg

The invention relates to a fuse element for an overvoltage protection device.

Overvoltage protection devices are intended to protect electrical systems against overvoltages, in particular against impulse events, such as occur when switching on devices or even when lightning strikes in the range of up to a few milliseconds. If such an event occurs, the occurring current should flow through the overvoltage protection device past the device for this short time. During the other time, the so-called nominal operation, usually no current or a very low current flows through the overvoltage protection device.

However, overvoltage protection devices are also subject to aging processes, so that damage to the overvoltage protection device can occur. These processes can also be caused by the derivation processes. If sustained damage to the surge protector occurs, i. If the error occurs, so can a not insignificant stream through the

Overvoltage protection device flow. In the worst case, the current reaches the short circuit current of the driving network.

Due to the longer-lasting current flow of great strength, a small amount of heat is generated even at low residual resistances of the damaged overvoltage protection device or its feeders, which can lead to fires or explosions of the overvoltage protection device or adjacent systems.

For this reason, overvoltage protection devices are increasingly provided with fuse elements to interrupt an occurring short-circuit current in case of failure can.

If the separation of overvoltage protection devices on AC voltage networks is generally unproblematic because of the periodic zero crossings, the separation of high-performance DC voltage networks is rather problematic because of the missing zero crossing. Of special In addition, photovoltaic systems are characterized as they have a special source characteristic.

From the state of the art, safety devices are known from the field of AC voltage networks which can interrupt a short-circuit current by means of a mechanical device already well before reaching the maximum amplitude. Even if an arc should occur during disconnection, the arc will be interrupted due to the subsequent zero crossing. A (re) ignition from the de-energized state, however, requires either very high voltages or very small distances. For this reason, based on the nominal operation small separation distances can be provided, which allows a small size of the securing devices.

Such measures are not immediately transferable for direct-voltage power grids as well as high-performance alternating voltage grids. Here is always to expect the occurrence of an arc. Since the zero crossings are absent in DC networks, the arc can not be extinguished without further extinction and thus the current flow. In powerful DC networks, the separation distance must be sufficiently large to prevent a renewed ignition. This requires appropriate measures to increase the so-called separation distance, so that the arc voltage increases so that the separation takes place by deleting the arc.

Although fuses offer because of the high power extinguishing power. These can be dimensioned so that the fuses trigger at a current that is greater than the rated current. However, at the same time, these fuses must also have a surge current of a pulse event, i. can carry the rated current of the surge protection device. To meet this requirement, a large fusible cross section must be provided. However, a high fusible cross section leads to the fact that so

Power to trip in case of error is high.

That Both requirements are difficult to meet at the same time, so that it comes to complex and therefore costly arrangements.

This is particularly difficult in photovoltaics, since in the case of a fault, the short-circuit current is only insignificantly above the rated current at maximum Light radiation is. In principle, then the fuse must detect a short circuit with only slightly exceeding the rated current and thus cause a shutdown. However, this is extremely difficult to achieve in practice. The invention is based on the object of making the switching capacity of fuses also available for overvoltage protection devices in high-performance AC voltage networks as well as in DC voltage networks.

The object is achieved by the features of the independent claims. Advantageous embodiments of the invention are specified in the subclaims.

The invention will be explained in more detail with reference to the accompanying drawings with reference to preferred embodiments.

Show it

Fig. 1 is a schematic inventive securing device according to the

Invention in a first state,

Fig. 2 is a schematic inventive securing device according to the

Invention in a second state, and

Fig. 3 single schematic views of elements of a securing device according to the invention. In Figure 1 and Figure 2 is a fuse element Sl for a

Overvoltage protection device ÜSE shown. The securing element has a multi-part housing with at least one first housing part G1 and a second housing part G2. For better visibility, the two housing parts are shown separately in Figure 3.

The first housing part G1 - shown in Figure 3 above - and the second housing part G2 - shown in Figure 3 below - engage at least partially positively in one another, so that a substantially pressure-resistant interior IR is formed. Through the interior IR leads a continuous conductor L, see Figure 1. This conductor is electrically contactable from the outside at the marked A and B points. For this purpose, for example, a suitable metallization can be provided on the housing parts G1 and G2.

The two housing parts G1 and G2 are mutually displaceable, as a comparison of Figure 1 and Figure 2 shows. In this case, the housing part G2 be moved inside the housing part G1, it being particularly advantageous if the second housing part G2 remains independent of the state within the first housing part, so that the size is defined by the first housing part. In the operating state of the fuse element, a first state, are the first housing part G1 and the second housing part G2 under bias F.

The bias F can be e.g. be provided by a spring which is introduced or formed between the first housing part G1 and the second housing part G2, without other forms of force, e.g. Magnetic force, thereby excluding.

In order to prevent an unwanted mutual displacement of the housing parts G1, G2, as shown in Figure 1, a shift is prevented by a holding mechanism H, wherein the continuous conductor L provides an electrically conductive connection.

In Figure 2, the holding mechanism H is released. Under the influence of the bias F, the housing parts G1 and G2 have now been shifted from each other. The conductor was mechanically stressed by the influence of the bias so far that the conductor L in the interior IR separates, ie the conductor L is interrupted. This can be achieved, for example, by fastening the conductor L on the housing part G1 on the side of the connection A as well as on the housing part G2 on the side of the connection B. In order to be able to carry the maximum pulse current of an associated overvoltage device USE, the continuous electrical conductor L is dimensioned such that the maximum pulse current of the overvoltage protection device ÜSE to be protected can be conducted through in the first state without destruction. The holding mechanism H has an external triggering T. By this triggering T, the holding mechanism H can be released. Such triggering T takes place by a measured variable in relation to the overvoltage protection device ÜSE to be protected.

That By means of the external triggering T, the switching capacity of a fuse arrangement can be utilized by subjecting the conductor L to a mechanical stress which leads to a disconnection. A possibly resulting arc leads to a melting of the conductor whereby the separation distance is increased and the arc voltage increases. If the arc voltage exceeds the mains voltage, the arc extinguishes and the circuit is interrupted. Preferably, at least a part of the conductor which is arranged in the interior IR, a fusible conductor.

In this way, a shutdown can also be done under DC network conditions, the surge current carrying capacity is available without restriction.

Advantageously, at least one of the two housing parts G1, G2 made of a material selected from the group ceramic, metal, plastic or composite material. This makes it possible to manufacture particularly cost-effective security elements.

Exemplary measured variables which can cause an external triggering T with respect to the overvoltage protection device ÜSE to be protected may be e.g. a leakage current measurement of the overvoltage protection device ÜSE to be protected and / or optical monitoring of the overvoltage protection device ÜSE to be protected and / or thermal monitoring of the overvoltage protection device ÜSE to be protected and / or a strain gauge on the overvoltage protection device ÜSE to be protected and / or another direct or indirect measurement of physical quantities that indicate a wear or defect of the overvoltage protection device ÜSE, be. That By suitable choice of one or more measured variables, a reliable shutdown in the event of a fault can be made possible by the external triggering T as well as an exact time separation. If the monitored measured variable exceeds a predetermined value, the disconnecting device is triggered and the faulty overvoltage protection device ÜSE is disconnected from the mains.

It is particularly advantageous if the interior IR is filled with an extinguishing medium LM. As a result, the switching performance can be improved or the space is minimized are, since the release of the holding mechanism H, an arc is formed, the parts of the conductor evaporates. The metal vapor condenses on the extinguishing agent LM and thus cools the arc, whereby the arc voltage increases. If the arc voltage exceeds the mains voltage, the arc extinguishes and the circuit is interrupted.

Exemplary extinguishing media LM are quartz sand and / or polyoxymethylene.

In a particularly favorable manner, the overvoltage device USE and a safety device according to the invention can also be combined as a fuse arrangement connected in series as an assembly. As a result, the externa ßere triggering T can be performed particularly secure to the fuse element. In particular, in a thermal monitoring, a spatially close arrangement offers, so as to keep the switching times low.

Exemplary overvoltage protection devices USE, which can be used with the fuse element S1 according to the invention, are selected from the group comprising spark gaps, varistors, suppressor diodes, semiconductor switches. Without further ado, a shift of the housing part to each other also

Be used for display purposes, such. to indicate the triggering. For this purpose, suitable viewing windows or color changes can be provided. Furthermore, both the external triggering T and the displacement of the housing parts G1, G2 and the triggering of the holding mechanism H can be used individually or in combination to trigger the triggering of the fuse element S1 to a remote monitoring device, e.g. to signal via a signal wire or other form of signaling.

In summary, the invention can be characterized in that the invention makes it possible to use the high current extinguishing capability in a compact design of fuses, but without having to accept the disadvantage of classical fuses, namely high tripping currents in the event of a fault. For this purpose, there are a (melting) conductor L and possibly the extinguishing agent LM in a pressure-resistant, at least two-part housing. The inner part of the housing, the second housing part G2, is designed so that it extends to one side of the housing Au ßengehäuses, the first housing part G1, can push out to a defined length. In order to effect the movement of the second housing part G2 out of the first housing part G1, a spring mechanism is used, for example, which is installed under a defined pretension F between the two housing parts G1, G2. The bias voltage F and the fixing of the second housing part G2 in the first housing part G1 is achieved, for example, via a triggerable detent as a shape of a holding mechanism H.

If the holding mechanism H is triggered by an external triggering T, the pretensioning F presses with a (defined) force on the second housing part G2 in such a way that it is pushed out. The force of the bias F is additionally chosen to be sufficiently large, so that the (melting) conductor L is torn by them. At the resulting separation point of the (fusible) conductor thereupon arises, depending on the application, an arc which further burns off the (fusible) conductor L and thus increases the separation distance. The metal vapor of the burning-down fusible conductor settles on a possibly existing surrounding extinguishing medium LM and is no longer available to the arc as conductive plasma. With a sufficiently high separation distance and a resulting high arc voltage, the arc extinguishes and the current flow is interrupted.

In addition, the resulting arc leads to a rapid increase in pressure. This additional pressure causes an increase in the speed of displacement of the second housing part G2. A faster erase process is the result. For this reason, a substantially pressure-resistant design of the interior IR is advantageous. This can be achieved, for example, by providing corresponding parallel protuberances on the sliding surfaces of the respective housing parts G1 and G2, so that guidance is provided with simultaneously reduced pressure compensation. Even in the case of a large overload, the (melting) conductor L evaporates without the use of external triggering T and thus leads to a separation. LIST OF REFERENCE NUMBERS

Fuse element Sl

Overvoltage protection device ÜSE first housing part G1 second housing part G2 pressure-resistant interior IR

Preload F

Holding mechanism H

Conductor external triggering T

Extinguishing medium LM

Claims

claims

1 . Securing element (SL) for an overvoltage protection device (ÜSE) comprising a multi-part housing having at least a first housing part (G1) and a second housing part (G2), the first housing part (G1) and the second housing part (G2) at least partially interlocking form-fitting manner, so that a pressure-resistant interior space (IR) is formed, the interior space (IR) having a continuous conductor (L), the first housing part (G1) and the second housing part (G2) being displaceable relative to one another,

Wherein in a first state, the first housing part (G1) and the second housing part (G2) are under bias (F), wherein a mutual displacement of the housing parts (G1, G2) is prevented by a holding mechanism (H), wherein the continuous conductor (L) provides an electrically conductive connection,

Wherein in a second state, the bias voltage (F) has led to a displacement of the housing parts (G1, G2) to each other, wherein the continuous conductor (L) is interrupted,

Wherein the continuous electrical conductor (L) is dimensioned so that the maximum pulse current of the overvoltage protection device (ÜSE) to be protected can be conducted through in the first state without destruction,

• characterized in that

• the holding mechanism (H) can be released by external triggering (T), the trigger being triggered by a measurand relative to the overvoltage protection device (TSE) to be protected.

2. Fuse element according to claim 1, characterized in that at least one of the two housing parts (G1, G2) is made of a material selected from the group ceramic, metal, plastic or composite material.

3. Fuse element according to one of the preceding claims, characterized in that the external triggering (T) by a leakage current measurement of the overvoltage protection device to be protected (ÜSE) and / or optical monitoring of the overvoltage protection device to be protected (ÜSE) and / or thermal monitoring of to be protected overvoltage device (ÜSE) and / or a strain gauge at the to be protected overvoltage protection device (ÜSE) and / or other direct or indirect measurement of physical quantities that indicate a wear or defect of the overvoltage protection device (ÜSE) is provided.

4. fuse element according to one of the preceding claims, characterized in that the interior space (IR) with an extinguishing medium (LM) is filled.

5. Fuse element according to claim 4, characterized in that the extinguishing medium (LM) has quartz sand and / or polyoxymethylene.

6. fuse element according to one of the preceding claims, characterized in that the securing element has a display means that makes the first and second state from the outside Shen recognizable.

7. fuse arrangement comprising an overvoltage protection device (ÜSE) and a fuse element (Sl) according to one of the preceding claims, wherein the overvoltage protection device (ÜSE) and the fuse element (Sl) are connected in series.

8. A fuse arrangement according to claim 6, wherein the overvoltage protection device (ÜSE) is selected from a group comprising spark gaps, varistors, suppressor diodes, semiconductor switches.