EP3178104A1

EP3178104A1 - Fuse for a device to be protected

Info

Publication number: EP3178104A1
Application number: EP15745221.0A
Authority: EP
Inventors: Rainer Durth
Original assignee: Phoenix Contact GmbH and Co KG
Current assignee: Phoenix Contact GmbH and Co KG
Priority date: 2014-08-04
Filing date: 2015-08-04
Publication date: 2017-06-14
Anticipated expiration: 2035-08-04
Also published as: CN106716591B; CN106716591A; US10134555B2; WO2016020381A1; DE102014215279A1; EP3178104B1; US20170236674A1

Abstract

The invention relates to a fuse (F) for a device (8) to be protected, said device being serially connected to the fuse (F). The series connection is connected to a supply network with a first potential (L) and a second potential (N) which differs from the first potential, and the fuse (F) has a first contact (1) and a second contact (2), said second contact (2) being used to electrically contact the device (8) to be protected. The fuse (F) has a fusible conductor (5) which connects the first contact (1) to the second contact (2). The fuse (F) further has an additional contact (3) which is insulated from the first contact (1) and the second contact (2) and which does not contact the fusible conductor (5) in a non-triggered state. The first contact (1) is directly connected to the first potential (L) during operation, and the device (8) to be protected is directly connected to the second potential (N) during operation. The additional contact (3) is likewise directly connected to the second potential (N) during operation. Additionally, a fourth contact (4) is provided which provides an external triggering. A triggering leads to an arc which directly or indirectly induces a fusion of the fusible conductor (5).

Description

Fuse for a device to be protected

The invention relates to a triggerable fuse for a device to be protected.

Both a variety of electrical devices, as well as electrical lines are protected in the event of faults by fuses. This can cause errors of various kinds. The most common errors can be understood as overload errors or short-circuit faults.

Typically, a fuse can then be triggered. In this case, the current flowing through the fuse heats the fusible conductor so far that at least partial, if not complete, melting of the fusible conductor occurs. This melting is usually associated with the occurrence of an arc whereby material of the fusible conductor evaporates. This steam settles elsewhere, with the arc cooling to the extent that the current is limited and eventually shut off.

The melting of the fusible conductor is determined by its material and geometry properties, so that depending on the material and / or geometry of the fusible conductor, a respective amount of heat Q for evaporation of the fusible conductor is necessary. Typically, the reflow characteristics and associated trigger currents are described by the melt integral I ² t.

However, it should be noted that this current, which represents a fault, still flows through the device to be protected or the system to be protected.

In particular, in the case of high short-circuit currents there is thus the danger of damage which is actually to be avoided, since the power limit of the device to be protected is exceeded. In addition, it should be noted that not only in the phase of melting the fusible conductor, a current flows, but also in the phase of extinguishing. That is, only the integration of the two current flow regions over time leads to the Durchlaßintegral.

Thus, in dimensioning, this passage integral must actually be taken into account in order to avoid damage.

However, this is often neglected incorrectly, so it comes to misdimensioning. Special requirements apply to the case in which the device to be protected is an overvoltage protection device, because they should allow high currents to pass in the short term without triggering the fuse, but at the same time also at low residual currents, as described e.g. in the event of damage to the overvoltage protection device or as a follow-on current, it may be necessary to switch off early. While the former requirement often leads to high rated current values of the fuse, the second requirement can be sensibly realized only with low nominal current values.

At the same time, there is an ever increasing trend towards small installation spaces. With previous fuses the requirements are therefore incompatible.

The invention is therefore based on the object to provide an improved fuse. 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 shows a first embodiment of a fuse according to the invention, Fig. 2 shows a second embodiment of an inventive

Fuse,

Fig. 3 shows a detail relating to embodiments of the invention, and 4 shows a use of different embodiments of a fuse according to the invention with an exemplary overvoltage protection device. Figures 1, 2 and 4 each show a schematic representation of a fuse according to the invention F.

The fuse F is connected in series with a device 8 to be protected, the series circuit being connected to a supply network having a first potential L and a second potential N different therefrom. The potentials L and N may be any suitable DC or AC potential. The potentials L and N thus form the supply network to which the series circuit is connected. In this case, the fuse F has a first contact 1 and a second contact 2. The second contact 2 is used for electrical contacting of the device 8 to be protected.

The fuse F further has a fuse element 5, which connects the first contact 1 with the second contact 2.

Furthermore, the fuse F at least one further contact 3, wherein the further contact 3 isolated to the first contact 1 and isolated to the second contact 2 is arranged. In a non-triggered state of the fuse F, the further contact 3 is in contact with the fusible conductor 5.

In operation, the first contact 1 is directly connected to the first potential L and the device 8 to be protected is directly connected to the second potential N. Furthermore, the further contact 3 is likewise directly connected to the second potential N during operation.

In addition, a fourth contact 4 is provided, which provides an external triggering, wherein upon triggering the fusible conductor 5 is caused directly or indirectly to melt. If an error occurs, for example as a result of an overcurrent or a short circuit, the fusible conductor 5 breaks down. The arc which occurs occurs in the region of the further contact 3. This is favored, inter alia, by the fact that the further contact 3 essentially has the potential N, so that in this case the voltage between the fusible conductor 5, which essentially has the potential L, is greater than the potential of the second contact 2, which is essentially the one same potential as the fusible conductor 5, wherein here a reduction by the potential drop on the protective device 8 occurs. This secondary arc will usually have a larger current, so that a safe separation of the fusible conductor and thus protection of the device 8 is ensured.

On the other hand, it is also possible to use the fourth contact 4 for external triggering. In this case, the fourth contact 4 - preferably as in the figures 1. 2 and 4 - in close proximity to the contact 2 and the further contact 3.

The sequence may be suitably chosen, e.g. For example, the further contact 3 and the second contact 2 may be adjacent to the fourth contact, or else the fourth contact is arranged above the further contact, and thus the further contact has the second contact 2 and the fourth contact 4 as neighbor.

The fourth contact 4 is also isolated in the fuse out. The fourth contact 4 may serve as spark gaps for the area of approach of the contact 3 to the fusible conductor 5. Thus you get a triggerable fuse.

As an electrical counter contact to the fourth contact 4, for example, the fusible conductor 5 or the contact 3 are used, but without being limited thereto. For example, a further contact (not shown) may also be provided, which is insulated from the second contact 2, the further contact 3 and the fourth contact 4. Depending on the configuration, an ignition now occurs between the fourth contact 4 and the further contact 3, between the fourth contact 4 and the fusible conductor 5, or between the fourth contact 4 and the further contact, not shown. In this case, the ignition can also be supported by a resistive support, as shown for example in DE 10146728 or by means of a transformer high-voltage pulse as shown in DE 50 2005 008 658 of the applicant. For this purpose, a suitable triggering can be provided by means of a suitably designed trigger device 9. If, for example, the device 8 to be protected detects a malfunction, then the trigger device 9 can be triggered. For example, various monitoring mechanisms for electrical circuits and devices for controlling the trigger device 9 can be used. Examples include arc detection and temperature monitoring called.

By triggering an ignition can be triggered with relatively low energy, resulting in a high-power arc between the other contact 3 and the fusible conductor 5, whereby the fusible conductor 5 separates so far that the power is turned off.

When separating the fusible conductor 5 there arises a primary arc. This burns first between the resulting at the separation point ends of the fusible conductor 5. Under the action of the arc now burn the separated ends of the fusible conductor 5, whereby the arc lengthened This process can vary depending on the design and location of the separation vonstattengehen. Due to the ionization caused by the arc, if not already done, the further contact 3 forms as (new) base point of the arc.

Thus, the flow of current through the device 8 to be protected is interrupted. This ensures that the device 8 to be protected in the event of a fault only has to carry that energy corresponding to i ² t, which is necessary for the melting and development of the first arc. If external triggering is provided by means of the triggering device 9, the current with respect to the device 8 to be protected is irrelevant. This energy is much lower than the energy that would flow through the device until the fuse (forward integral) is cleared. As a result, the fused circuit is greatly relieved.

In an advantageous embodiment, the fusible conductor 5 has a predetermined breaking point in the region of the further contact 3. In a short circuit case of the electrical device to be protected, the fusible conductor 5 will now melt in the region of the predetermined breaking point 6. Such predetermined breaking points 6, for example, by rejuvenation (s) and / or perforation (s) of the fusible conductor. 5 be realized. An arc is generated and in turn the arc burns off the two ends of the fusible conductor 5, thereby lengthening. In the region of approach of the contact 3 to the fusible conductor 5, the arc results in ionization, so that the arc can select the contact 3 as a new base point or due to the low resistance (eg with appropriate dimensioning) and / or arrangement relative to the second contact. Thus, the flow of current through the device 8 to be protected is interrupted. This ensures that the device to be protected 8 in the event of a fault, only that energy must carry according to i ² t, which is necessary for melting the predetermined breaking point 6 and the development of the first arc. This energy is much lower than the energy that would flow through the device until the fuse (forward integral) is cleared.

Particularly advantageous may also be provided that the fusible conductor 5 is filled with an extinguishing medium, in particular with sand and / or POM (polyoxymethylene). As a result, the switching characteristics in terms of the switching capacity and the speed are improved, since now an improved cooling of the arc is provided, whereby the switching capacity and the switching speed can be improved. In a further embodiment of the invention, the further contact 3 is designed like a disk, wherein the fusible conductor 5 is guided in a recess or through an opening. As a result, the production can be made particularly simple and thus cost. For example, the contact may be configured as a disk having a substantially circular opening.

In a further embodiment of the invention, the fourth contact 4 is designed like a disk, wherein the fusible conductor 5 is guided in a recess or through an opening. As a result, the production can be made particularly simple and thus cost. For example, the contact may be configured as a disk having a substantially circular opening.

According to one embodiment of the invention, which is shown in Figures 2 and 4, the fuse F may further comprise an auxiliary fusible conductor 10 which is in electrical connection with the first contact 1 and which is in electrical connection with the fourth contact 4. As a result, the operation z. B. with respect to spark gaps as a device to be protected 8 can be improved. This embodiment is particularly suitable for securing auxiliary circuits of high-power electrical appliances. It would be conceivable, the electronic measuring control and safety devices of large engines and other high-performance consumers who have auxiliary circuits of low power, but where the failure of the auxiliary circuit should lead to an immediate shutdown (emergency shutdown) of the main unit.

In particular, the protection of ignition circuits of spark gaps is conceivable. Ignition circuits are usually in terms of their electrical parameters, e.g. their electrical cross-section, designed much smaller than the electrical main path of the spark gap, since the backup fuse is basically to be dimensioned for the maximum derived surge current pulse. Therefore, it may be necessary to secure ignition circuits by additional protective devices, which requires additional space. Furthermore, the triggering of a protective device in the ignition circuit must additionally signaled and given If extra be reported, since the spark gap with unusual ignition circuit typically provides reduced protection. Thus, there is a significant additional effort that can be minimized by the integration of the auxiliary fusible conductor as a backup for the ignition circuit in the backup, and in addition a gain in security is generated by the spark gap 8 is completely separated electrically.

For example, the trigger device 9 for a spark gap can be designed as a device 8 to be protected, as shown in FIG. For the design of the fusible conductor 5 and the auxiliary fusible conductor 10, different embodiments may be provided. Thus, as shown in FIGS. 2 and 4, the fusible conductor 5 and the auxiliary fusible conductor can be guided in wire-like fashion at least in sections, or as shown in FIG. 3 on the left-hand side, the auxiliary fusible conductor 10 can be separated in sections from the fusible conductor 5. For example, the auxiliary fusible conductor 10 can be separated in sections by stamping, separating, milling or the like from the fusible conductor 5.

Or, however, the auxiliary fusible conductor 10 may, as shown in FIG. 3 on the right, in sections also surround the fusible conductor 5 in a helical manner. In this case, the auxiliary fusible conductor 10 should extend at least in the region of the approach of the contact 3 to the melting timer 5 insulated from the fusible conductor 5, so that a substantially defined ignition point is present. In addition, the fusible conductor 5 and the auxiliary fusible conductor 10 can have one or more predetermined breaking points 6 in the region of the further contact 3 or in the region of the fourth contact 4.

Particularly advantageously, the fuse F according to the invention in a fuse arrangement A, e.g. as shown in Figure 4, used in addition to the fuse F and the device to be protected 8 and a trigger device 9, which is connected to the fourth contact 4 and an "external" triggering, ie a triggering, not directly the Hauptleitpfad owed.

In this case, the device to be protected 8 may have an overvoltage protection device, for example a spark gap and / or a varistor and / or a transient voltage suppressor diode. In the embodiment according to FIG. 4 there is further provided a wear monitoring device 12, which is e.g. is designed as protected with a degradable material protected contact. The trigger 9 is then e.g. On the output side connected to the wear monitoring device 12 of the spark gap 8 to the fourth contact 4.

In Figure 4, both the ignition circuit, as well as the wear monitoring device 12 is secured over the auxiliary fusible conductor 10, so that both the overload of the ignition circuit and an overload of the spark gap 8 in its interior by triggering the auxiliary fusible conductor 10 and subsequent burning of the main fusible conductor 5, the spark gap 8 completely disconnected from the mains.

An arc between the ends of the fired Hilfsschmelzleiters 10 is formed in the region of approach between the contact 4 and the fusible conductor 10 by overloading the auxiliary fusible conductor 10. By means of this arc, a second arc ignites the fusible conductor 5 and the contact 3, which is used to burn the fusible conductor 5, ie to trigger the fuse leads. To improve the ignition behavior of the auxiliary fusible conductor 10 in the approximation of the Contact 3 to the fuse element 5 have a predetermined breaking point 6, which breaks when overloading of the fuse conductor first, so that at this point a first arc is formed. With a suitable dimensioning of the fusible conductor 5 and the auxiliary fusible conductor 10, it is thus possible by means of a low tripping current in the fusible conductor 8 to trigger the high-current carrying fuse F, without the current until the triggering and deletion of the high current carrying fuse F (Durchlaßintegral i ² t) by the protective device 8 must flow. In particular, the auxiliary fusible conductor 10 can be energized and triggered by switching devices in the device to be protected or a trigger device 9. Thus one obtains a triggerable fuse F.

To introduce the isolated potentials of the further contact 3 and the fourth contact 4, the usual mechanisms for the isolated implementation of potentials can be used. Particularly advantageous is the layered structure of metal plates and insulating plates with a Sicherungsendplatte for completion. In this structure, the various potentials can be introduced through the stacked insulated plates. The disk stack may e.g. be bolted.

The triggering of the fuse can be signaled according to the usual mechanisms.

The presented invention can be used particularly advantageously in the field of electromobility as well as the generation of electrical energy by means of photovoltaics. Here it is often stated that vehicles or equipment or devices should meet certain safety criteria, for example, in an accident or fire, no danger to occupants or helpers. Then, an automatically or externally triggerable and high-performance shutdown of the power source as an example of a device to be protected 8 can be provided by the invention readily.

LIST OF REFERENCE NUMBERS

Fuse F

First contact 1

Second contact 2

Further contact 3

Melt conductor 5

Predetermined breaking point 6

Device to be protected 8

Trigger device 9

Auxiliary fusible conductor 10

Wear monitoring device 12 First potential L Second potential N Fuse arrangement A

Claims

claims

1 . Fuse (F) for a device (8) to be protected, which is connected in series with the fuse (F), the series circuit being connected to a supply network having a first potential (L) and a second potential (N) different therefrom, wherein the fuse (F) has a first contact (1) and a second contact (2), wherein the second contact (2) for electrically contacting the device to be protected (8), wherein the fuse (F) comprises a fuse element (5 ) having the first contact (1) with the second contact

(2), the fuse (F) continuing to make another contact

(3), wherein the further contact (3) is insulated from the first contact (1) and insulated from the second contact (2) and is in a non-triggered state in contact with the fusible conductor (5), the first contact (1 ) is directly connected in operation with the first potential (L), and wherein the device to be protected (8) in operation with the second potential (N) is directly connected, wherein the further contact (3) in operation also with the second potential (N) is directly connected, further providing a fourth contact (4) providing external triggering, triggering resulting in an arc causing the fuse element (5) to melt, directly or indirectly.

2. Fuse (F) according to claim 1, characterized in that the fusible conductor (5) in the region of the further contact (3) has a predetermined breaking point.

3. Fuse (F) according to claim 1 or 2, characterized in that the fusible conductor (F) with an extinguishing medium, in particular with sand and / or POM, at least partially surrounded.

4. Fuse (F) according to one of the preceding claims, characterized in that the fourth contact (4) is designed like a disk, wherein the fusible conductor (5) is guided in a recess or through an opening.

5. Fuse (F) according to one of the preceding claims, characterized in that the fuse (F) continues to have a Auxiliary fusible conductor (10) which is in electrical connection with the first contact (1) and which is in electrical connection with the fourth contact (4).

6. fuse (F) according to the preceding claim, characterized in that the further contact (3) is designed like a disk, wherein the auxiliary fusible conductor (10) is guided in a recess or through an opening.

7. fuse arrangement (A) comprising a fuse (F) according to one of the preceding claims and a device to be protected (8), further comprising a trigger device (9), which is connected to the fourth contact (4) and allows external triggering.

8. fuse arrangement (A) according to the preceding claim, wherein the device to be protected (8) comprises an overvoltage protection device.

9. fuse arrangement (A) according to the preceding claim, characterized in that the overvoltage protection device is selected from a group having spark gaps, varistors, transient voltage suppressor diodes.

10. fuse arrangement (A) according to any one of the preceding claims 8 to 9, characterized in that the overvoltage protection device is a spark gap with a Zündhilfselektrode, wherein the trigger device (9) has an ignition circuit, and wherein the ignition circuit with the auxiliary electrode of the spark gap (8) connected is.

1 1. Fuse arrangement (A) according to one of the preceding claims 8 to 10, characterized in that the overvoltage protection device is a spark gap with a wear monitoring device (12), wherein the trigger device (9) with wear monitoring device (12) of the spark gap (8) is connected.