DE102011053414B4 - Overvoltage protection device with a thermal cut-off device - Google Patents

Abstract

An overvoltage protection device having a thermal cut-off device (1), the thermal cut-off device comprising an electrically insulating carrier (T) with a low heat conduction, the carrier (T) having at least one electrical conductor (L) on a first side (O), wherein the electrical conductor (L) at a feedthrough point (DS) through the support (T) through to the opposite second side (U) is guided, wherein the electrical conductor (L) continues on the second side (U) in the region of the implementation site (DS ) has a contact point (KS) spaced from the leadthrough point (DS), with which the overvoltage protection device (ÜSG) is electrically contacted, wherein the support (T) in the region of the contact point (KS) by means of a connection means (5, 15) on the surge protective device (ÜSG ) is thermally releasably fixed, wherein the carrier (T) over the overvoltage protection device (ÜSG) biased (F1, F2), so that in the case of Heating the contact point (KS) the connecting means (5, 15) loses its fixing property and the mechanical bias causes the carrier (T) to release the electrical connection from the conductor (L) to the surge protective device (ÜSG), wherein the conductor (L) is dimensioned so that it can carry at least the nominal leakage current or the permitted transient pulse current of the overvoltage protection device (ÜSG), and wherein the carrier (T), when the connection between the conductor (L) and overvoltage protection device (ÜSG) has been solved, the contact point ( KS-ÜSG) on the surge protective device (ÜSG) with an electrically insulated layer (I) covered, so that arcs are prevented.

Description

The invention relates to an overvoltage protection device with a thermal separation device.

Conventional overvoltage protection devices have a varistor and / or a gas discharge arrester (ÜsAg). In order to protect the varistor or the excess from overheating, elements are provided which disconnect the current path to the varistor or excess if required.

A known possibility of such a separating element is a thermal fuse. A disadvantage of these temperature fuses, however, is that the separation is rather slow, typically in the range of a few seconds, ie. H. Thermal fuses are comparatively sluggish.

Another way to produce such a separator is a solder joint. In this case, a contact of a feeder is soldered directly to the varistor and set under a mechanical bias, see for example DE 10 2009 036 125 A1 , If a correspondingly high heat generation of the varistor occurs, the solder connection melts and the bias voltage disconnects the electrical contact. This type of separation device, like the temperature fuse, is rather sluggish and typically responds in the lower second range.

However, the inertia of the known separation devices is still a danger, since often the separation takes place only when the protected varistor or ÜsAg is already damaged or destroyed, which can have far-reaching consequences.

Another disadvantage is that the known constructions must also operate considerable effort to prevent or extinguish possible arcs, which are a problem especially in DC applications.

The US 2010/0 290 168 A1 shows an explosion-proof and fire-resistant, removable safety overvoltage module. The safety overvoltage module has inter alia an overvoltage unit and a functional part which is pivotably mounted relative to the overvoltage unit and has a first fastening region and a second fastening region. The first attachment region has a conductive unit with an electrically conductive pin, which is guided by the functional part. The electrically conductive pin is connected via a fusion connection with the overvoltage unit. Furthermore, the functional part is biased against the overvoltage unit by a spring connected to the first fastening area. Depending on the biasing force of the spring upon reaching a certain melting temperature of the fused connection fails the connection between the electrically conductive pin and the overvoltage unit, whereby the functional part is pivoted relative to the overvoltage unit due to the biasing force by the spring.

The WO 2011/102 811 A2 shows an overvoltage circuit breaker with a rotating disk and an electronic assembly to improve the reliability. The overvoltage power circuit breaker includes, among other things, a varistor, a varistor-mountable bracket having an oval opening, a rotatable spring-biased circular disk, and a connection electrode. The connection electrode is connected to the varistor through an opening in the biased disc and through the oval opening of the holder via a temperature sensitive flux. The connection of the connection electrode to the varistor holds the disc in a biased position.

The invention is based on the object to provide an overvoltage protection device with a thermal separator available, which reacts much faster and is inexpensive. Furthermore, it is a further object of the invention to avoid arcs as far as possible or to extinguish them early.

The object is achieved according to the invention by the features of the independent claim. 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.

It shows

1 schematically a thermal separation device according to a first preferred embodiment of the invention,

2 1 is a schematic exploded view of the thermal separator according to the first preferred embodiment of the invention;

3 schematic details of a thermal separator according to the first preferred embodiment of the invention,

4 schematically further details of a thermal separating device according to the first preferred embodiment of the invention,

5 schematically further details of a thermal separating device according to the first preferred embodiment of the invention, in particular when used in a double arrangement,

6 1 is a schematic plan view of the underside of a thermal separating device according to a further preferred embodiment of the invention,

7 1 is a schematic plan view of the upper side of a thermal separating device according to the further preferred embodiment of the invention,

8th schematically a thermal separation device according to yet another preferred embodiment of the invention,

9 1 is a schematic exploded view of the thermal separating apparatus according to the still further preferred embodiment of the invention;

10 schematically a view of a housing for use with the still further embodiment of the invention

11 schematically a sectional view of the housing for use with the still further embodiment of the invention and

12 schematically the mathematical relationship of the directional designations used.

The 1 to 12 show a thermal separator 1 , Insofar as identical or similar reference symbols are used in the following figures and the associated description, this can be seen as an indication that the correspondingly designated elements have essentially the same function.

In 1 schematically is a first embodiment of a thermal separation device 1 for a surge protective device ÜSG shown. The thermal separator 1 has an electrically insulating support T. This carrier T has a low heat conduction. On the first side O (top) of the carrier T, this has one or more electrical conductors L. In the 1 to 3 only one conductor L is shown, but without being limited thereto. The conductor or conductors L are dimensioned such that at least the rated discharge current or the permitted transient pulse current of the overvoltage protection device ÜSG can be carried. Furthermore, the conductor or conductors L can also be dimensioned such that they can carry at least the nominal leakage current of the overvoltage protection device ÜSG, as well as the maximum leakage current and a specified maximum future short-circuit current.

The conductor L has a contact point KS-ZL on the supply side to the varistor or ÜsAg. This contact point KS-ZL can be designed for one or - as far as several conductors L are present - for individual or all conductors L together. This contacting KS-ZL is spaced from the implementation site DS.

At a feedthrough point DS, the electrical conductor L is passed through the carrier T to the opposite second side U (below). The type of implementation may be adapted to the technology used. For example, the conductor L may be designed as a conductor track and the implementation may be designed as a through-connection.

On the second side U is - as in 2 better seen - arranged a contact point KS. This contact point KS is used to make contact with a surge protection device ÜSG, z. B. at a provided there contacting KS-ÜSG.

The contacting KS-ZL is spaced from the implementation site or the contact point KS.

When using the thermal separator 1 the carrier T is thermally releasably fixed in the region of the contact point KS by means of a connecting means on the overvoltage protection devices ÜSG. Here, the fixation - as in 5 shown on the right half - both at the contact point KS itself, z. B. by a solder joint 15 , as well as adjacent to the contact point KS by means of a thermally softenable adhesive 5 be thermally releasably fixed to the overvoltage arrester ÜSG. In this respect, the area also refers to the neighborhood to the actual electrical contact point. In 5 is the solder connection 15 a contact point KS on the carrier T with a contact point KS-ÜSG shown as a vertically striped rectangle. In contrast, the fixation by means of a thermally softenable adhesive 5 shown as a checkerboard-like rectangle. Both options can be used as an alternative to each other or as a supplement to each other.

In order to achieve separation of the current path, a bias voltage F1, F2 between the carrier T and the overvoltage protection device ÜSG is furthermore provided. The bias can be different in nature, z. B. a spring preload or a magnetic bias. Essential to the bias is that this leads to softening that the bonding agent its fixing property loses, and thus the electrical connection by a spatial separation of the respective contact points KS, KS-ÜSG separates.

The invention makes use of the fact that now heating due to the carrier can not initially be derived as easily as before in a direct contact, since the electrically insulating support physically also has a lower heat transport capacity. A copper cladding for conductor L has such a low heat transfer capacity that a significant amount of heat removal is omitted. Thus, a heat input remains at the contact point or the junction as compared to conventional arrangements. Since heat is derived only in insignificant proportion, now a much faster switching behavior is possible. Typical values for the response to heating are in the range of less than 1 second, usually even less than 1/10 second, these values being dependent on the flowing current.

Furthermore, since the carrier T is constructed of electrically insulated material and the conductor L is formed on the upper side, the carrier T covers the contact point KS-ÜSG after heating, as soon as the bias has shifted the carrier. This arrangement avoids arcing.

In 2 is further shown that the (lower) side U of the carrier T with the exception of the contact point KS has a coating I. This coating I as well as the carrier T itself can have an outgassing material in order, in the case of an emerging arc, to blow it out. Suitable materials are, for example, aromatic hydrocarbons, aliphatic hydrocarbons, thermoplastics, in particular polyactides, polyacetates, celluloid, polyolefins, PMMA, polyphenylenes or polyphenylene sulfide. These materials may for example also be part of a solder resist.

In 3 different possibilities for a bias F1, F2 are shown. For example, a lateral spring F1 may be provided to cause the carrier T to rotate about a pivot point D relative to the overvoltage arrester ÜSG. Alternatively or additionally, a torsion by means of a prestressed coil spring F2 can be generated. In this respect, the design of both the movement itself (shift in one direction, rotation) are no limits. Likewise, by different design of the bias, z. B. by spring or magnet various configurations possible. Common to the embodiments that the bias voltage F1, F2 essentially leads to a movement in a plane normal to the contact point on the overvoltage arrester ÜSG, ÜSG1, ÜSG2, since in this case an overlap of the contact point KS-ÜSG is achieved by the insulating support T and thus the Non-education of electric arcs is favored. Typical magnitudes for the forces of the bias voltage are in the range of 1 Newton and depend inter alia on the size of the carrier to be moved T.

It is preferred if the carrier T is made of a printed circuit board material, for example epoxy resin, FR4 or the like. Material thicknesses for the carrier T of less than one millimeter, for example 0.5 mm, have proven to be favorable in order to achieve the desired effect. Preferably, the conductors L are also made of a suitably applied electrically conductive material, for example a Kupferkaschierung. So z. B. at a material thickness of about 105 micrometers and a conductor width of a conductor L of about 1 mm, a surge current of, for example, 3 kA of the form 8/20 μs readily be worn. In the embodiment described above, a nominal leakage current In of about 3 kA up to 5 kA and a maximum leakage current Imax of about 15 kA for a pulse shape of 8/20 μs and a max. Follow-up current / prospective short-circuit current Ip of approximately 5 kA of a Class III arrester can be realized with a carrier material of approximately 0.5 mm. As previously described, several conductors L can be provided. Such embodiments are for example in 4 to 9 shown. The conductors L can each have their own contact points KS - see 4 - Or single or all conductors L are combined in a common contact KS. The same applies to the contact point for the KS-ÜSG overvoltage protection device.

Furthermore, as in 5 also shown two overvoltage protection devices ÜSG1, ÜSG2 be arranged relative to a center electrode ME. Then, it is useful for each overvoltage protection device ÜSG1, ÜSG2 to have a thermal separation device in the form of a carrier T. The two varistors ÜSG1, ÜSG2 are surrounded by a dotted illustrated insulating layer. In the insulating layer itself, the contact points KS-TSG are designed as window electrodes. Alternatively, ÜsAgs can be installed instead of the varistors.

In 6 and 7 a further embodiment of the invention is shown. This is essentially based on a rotational movement about a pivot point D. Here, a plurality of plated-through holes in the region of the implementation site - shown as a light circles - provided. 6 shows the bottom while 7 this mirrored the top in relation to an overvoltage device with contacting the carrier T shows. Without being limited thereto, a lateral bias is represented by a spring F1. Without further ado, it is also possible alternatively or additionally to provide a pretensioning F2 at the pivot point D which, as in FIG 3 shown to lead to a twist. The contact point KS-ZL for the supply line E is selected in the pivot point or near the pivot point to have to hold as little material for a rotational movement of the supply line E. Since the carrier is chosen to be large enough, a rotating displacement is sufficient to lead to an overlap of the contact point KS-ÜSG through the now rotated via the contact point KS-ÜSG carrier T and thus to avoid an arc.

8th and 9 show still another embodiment of the invention. This further embodiment has a rather round carrier T and is particularly suitable for ÜSGs with round varistors or ÜsAgs. It shows 9 a sectional view taken along the dashed line AA 8th , Again, DS has numerous vias to carry a given current. The varistor or ÜsAg ÜSG is advantageously used in a housing G, which in perspective in 10 and on average in 11 along the section line AA 10 is shown. This housing G has in the middle, at least in sections, a circular protuberance A, which is adapted in height to a carrier T to be inserted. The protuberance A forms the axis of rotation D. The contact point KS-ZL for the supply line E is chosen in the pivot point or near the pivot point to have to hold as little material for a rotational movement of the supply line E. At the edge, the housing G has a window-like opening OE. This is designed so that the contact point KS of the carrier can contact the varistor or ÜsAg ÜSG. A suitably mounted (and not shown) bias ensures that the carrier T is rotated as soon as the softening of the connecting means 5 . 15 entry. Again, a quick separation is made possible and with a rotation of the carrier T relative to the ÜSG by about 180 ° is also achieved that the distance of the contact point KS to contact point KS-ÜSG is maximized, which counteracts the formation of arcs.

As far as normal orientations and movements with respect to the normal orientation have been mentioned above, these are again with reference to explained. Both the overvoltage protection device ÜSG and the carrier T have surfaces which are parallel to one another. On these surfaces, the respective contact points KS, KS-ÜSG are arranged. These levels, mathematically, have a normal vector N. A movement can now take place as a rotation about the norm vector or as a translation in a plane which also has the same norm vector or else be a rotational and translatory movement in a plane which also has the same norm vector.

LIST OF REFERENCE NUMBERS

1

Thermal separator

ÜSG, ÜSG1, ÜSG2

Overvoltage protection device, varistor, ÜsAg

T

electrically insulating support

L

electrical conductor

O

first side, top

U

second side, bottom

KS

contact point

KS-ÜSG

Contact point overvoltage protection device

KS-ZL

Contact point Zuleiter

DS

Implementing Agency

D

pivot point

e

Supply, electrode

ME

center electrode

F1, F2

biasing means

I

coating

G

casing

A

protuberance

OE

opening

Claims (8)

Surge protection device with a thermal separation device ( 1 ), wherein the thermal separating device comprises an electrically insulating carrier (T) with a low heat conduction, wherein the carrier (T) has at least one electrical conductor (L) on a first side (O), wherein the electrical conductor (L) at a Implementation point (DS) through the support (T) through to the opposite second side (U) is guided, wherein the electrical conductor (L) continues on the second side (U) in the region of the implementation site (DS) to the implementation site (DS) spaced contact point (KS), with which the overvoltage protection device (ÜSG) is electrically contacted, wherein the carrier (T) in the region of the contact point (KS) by means of a connecting means ( 5 . 15 ) is thermally detachably fixed to the overvoltage protection device (ÜSG), wherein the carrier (T) is biased relative to the overvoltage protection device (ÜSG) (F1, F2), so that in case of heating of the contact point (KS) the connection means ( 5 . 15 ) loses its fixing property and the mechanical bias causes the carrier (T) to release the electrical connection from the conductor (L) to the overvoltage protection device (ÜSG), wherein the conductor (L) is dimensioned such that it can carry at least the nominal leakage current or the permitted transient pulse current of the overvoltage protection device (ÜSG), and wherein the carrier (T) when the connection between the conductor (L) and overvoltage protection device (ÜSG) is released was covered, the contact point (KS-ÜSG) on overvoltage protection device (ÜSG) with an electrically insulated layer (I), so that arcs are prevented. Overvoltage protection device according to claim 1, characterized in that the conductor (L) is dimensioned such that it can carry at least the nominal leakage current of the overvoltage protection device (ÜSG), as well as the maximum leakage current and a specified maximum future short-circuit current. Overvoltage protection device according to one of the preceding claims, characterized in that the overvoltage protection device (ÜSG) and the carrier (T) have surfaces which are parallel to one another, wherein the respective contact points (KS, KS-ÜSG) are arranged on these surfaces, wherein the mechanical Prestressing (F1, F2) essentially results in a movement representing a rotation about the normal vector of the parallel faces, a translation in a plane which also has the same normal vector, or a rotational and translational movement in a plane which is also the plane has the same normal vector. Overvoltage protection device according to one of the preceding claims, characterized in that the carrier (T) has a pivot point (D) and that the mechanical bias (F1, F2) substantially to a rotational movement about the pivot point substantially in a plane normal to the contact point (KS -ÜSG) leads to the surge protective device (ÜSG). Overvoltage protection device according to one of the preceding claims 1 to 4, characterized in that the carrier (T) has a pivot point (D) and that the mechanical bias substantially to a displacement movement of the carrier relative to overvoltage protection device (ÜSG) in a plane normal to the contact point on Overvoltage protection device (ÜSG) leads. Overvoltage protection device according to one of the preceding claims, characterized in that the carrier (T) comprises a printed circuit board material. Overvoltage protection device according to one of the preceding claims, characterized in that the lead-through point (DS) has a plurality of electrical conductors (L). Overvoltage protection device according to one of the preceding claims, characterized in that the carrier (T) has an outgassing material selected from the group of aromatic hydrocarbons, aliphatic hydrocarbons, thermoplastic, in particular polyactides, polyacetates, celluloid, polyolefins, PMMA, polyphenylenes or polyphenylene sulfide, so that in the case of an arc, this can be blown out.

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