DE102011053414A1 - Thermal disconnecting device for overvoltage protection devices - Google Patents

Abstract

The invention relates to a thermal separation device (1) for overvoltage protection devices (ÜSG). The thermal separation device has an electrically insulating support (T), which has a low heat conduction. The carrier has at least one electrical conductor (L) on a first side (O), wherein the at least one electrical conductor (L) at a feedthrough point (DS) through the carrier (T) through to the opposite second side (U) out is. Furthermore, the electrical conductor (L) has a contact point (KS) on the second side (U) in the region of the leadthrough point (DS) for contacting with an overvoltage protection device, which is at a distance from the leadthrough point. The carrier is in the region of the contact point (KS) by means of a connecting means on overvoltage protection devices (ÜSG) thermally detachable fixed. The carrier (T) is biased (F1, F2) with respect to the overvoltage protection device (ÜSG), so that in the case of heating of the contact point, the connecting means loses its fixing property and the mechanical bias causes the carrier the electrical connection from the conductor (L) to overvoltage protection devices (ÜSG) to solve. In this case, the conductor (L) is dimensioned so that it can carry at least the nominal leakage current of the overvoltage protection device (ÜSG).

Description

The invention relates to a thermal separation device for overvoltage protection devices.

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 invention is based on the object to provide a thermal separation device for surge equipment 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 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.

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 substantially 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 an overvoltage protection device ÜSG, for example at a provided there KS-ÜSG contact point.

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, for example 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 may be different in nature, e.g. a spring preload or a magnetic bias. Essential to the bias is that this leads to softening that the connecting means loses its fixing property, and thus the electrical connection by a physical separation of the respective contact points KS, KS-TSG 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, a wide variety of configurations of the bias, for example by means of 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. Thus, for example, with a material thickness of approximately 105 micrometers and a conductor width of a conductor L of approximately 1 mm, a surge current of, for example, 3 kA of the 8/20 μs form can be readily carried. 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 the varistor or ÜsAg ÜSG can contact. 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 between 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

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009036125 A1 [0004]

Claims (10)

Thermal separation device ( 1 ) for overvoltage protection devices (ÜSG), comprising an electrically insulating support (T), which has a low heat conduction, wherein the support has at least one electrical conductor (L) on a first side (O), wherein the at least one electrical conductor (L) at a feedthrough point (DS) through the support (T) on the opposite second side (U) is guided, wherein the electrical conductor (L) further comprises a contact point (KS) on the second side (U) in the region of the implementation site (DS ), for contacting with an overvoltage protection device, which is spaced from the leadthrough point, wherein the carrier (T) in the region of the contact point (KS) by means of a connecting means on the overvoltage protection device (ÜSG) is thermally detachably fixable and wherein the carrier (T) relative to the overvoltage protection device (ÜSG) biased (F1, F2), so that in case of heating of the contact point, the connecting means its f ixierende property loses and the mechanical bias causes the carrier to release the electrical connection from the conductor (L) to the surge protective device (ÜSG), wherein the conductor (L) is dimensioned such that it at least the rated leakage current or the transient transient pulse current of the surge protective device ( ÜSG). Thermal separating device according to claim 1, characterized in that the conductor (L) is dimensioned so 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. Thermal separating device according to claim 1 or 2, characterized in that the carrier (T) when the connection between the conductor (L) and overvoltage protection device (ÜSG) has been solved the contact point (KS-ÜSG) on overvoltage protection device (ÜSG) with an electrically insulated layer ( I), so that arcs are prevented. Thermal separating device according to one of the preceding claims, characterized in that the mechanical bias (F1, F2) essentially leads to a movement in a plane normal to the contact point on the overvoltage protection device (ÜSG). Thermal separating device according to one of the preceding claims, characterized in that the carrier 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 on the surge protection device (ÜSG ) leads. Thermal separating device according to one of the preceding claims 1 to 4, characterized in that the carrier has a pivot point 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 the overvoltage protection device (ÜSG) leads , Thermal separating device according to one of the preceding claims, characterized in that the carrier (T) comprises a printed circuit board material. Thermal separating device according to one of the preceding claims, characterized in that the lead-through point (DS) has a plurality of electrical conductors (L). Thermal separating device according to one of the preceding claims, characterized in that the carrier comprises 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 case an arc of this can be blown out. Thermal separating device according to one of the preceding claims, characterized in that the carrier (T) in the region of the contact point (KS) by means of a thermally softenable adhesive ( 5 ) is thermally detachably fixed to the overvoltage protection device (ÜSG) and / or the carrier (T) in the vicinity of the contact point (KS) by means of a connection means ( 15 ) to overvoltage protection devices (ÜSG) is thermally releasably fixed.

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