SI23040B - Varistor with defined weak spot within its structure - Google Patents

Abstract

The invention refers to varistors featuring a deliberately and position defined weak spot on the structure of varistors and inside of them with the basic purpose of upgrading the varistor featuring a thermal disconnector in surge protection modules. The varistor with the deliberately integrated weak spot inside the structure according to requirement number 1 is characterised in that inside the varistor body (1) there is a weak spot (2) of circular shape with depth (2a) and the spot on the body (1) can beselected randomly considering the varistor size. The varistor despite the weak spot (2) where the local overheating of the body (1) takes place does not negatively affect the energy absorption of the varistor. Upon the passing of the current through the varistor regardless of the reason for such a current, there is always a slightly higher current running through the weak spot (2) of the varistor body (1) compared to the remaining structure. Upon the process of adequate current distribution inside thevaristor this can be triggered at the defined integrated weak spot (2) of the varistor and the process of local heating is started which due to the high conductive factor quickly spreads across the complete varistor body (1). In the case of high but short power overloads the temperature is quickly transferred from the weak spot (2) to the whole varistor body (1), while in the case of longer overloads the deliberately integrated weak spot (2) acts as a relatively constant source of temperature which enablesthe upgraded thermal disconnecting system to perform the adequate reaction and to physically disconnect from the system.

Description

Original document published without description

Claims (8)

PATENT CLAIMS A varistor having a purpose-built weak point in a structure comprising a base material of ZnO and the corresponding dopants and having a purpose-built weak point that may lie on the surface or inside the body of the varistor, characterized in that in the body (1) of the varistor at least one weak point (2), preferably in a circular shape, with a depth (2a), so that the position on the body (1) can be chosen arbitrarily in relation to the size of the varistor so that the varistor, in spite of the weak point (2) where the local overheating of the body 1) does not impair the energy absorption of the varistor, so that, when passing through the varistor, regardless of the cause of the current, the varistor of the body (1) travels through the weak point (2) of the varistor at a slightly higher current than over the rest of the structure, the division of the current through the varistor triggers it into the defined weak point (2) of the varistor in order to begin the process of appropriate local heating, which, due to the high conductivity coefficient, rapidly extends to the whole body (1) vari in the case of large but short-term electrical overloads, the temperature is transferred very quickly from the point of weakness (2) to the whole body (1) of the varistor, while in case of longer time overloads, the purpose-built weak point (2) acts as a relatively constant source temperature, which allows the upgraded thermosetting system to respond appropriately and physically shut down the system. A varistor with a purpose-built weak point in the structure according to claim 1, characterized in that in a place with a purpose-built weak point, the temperature in the case of an electrical overload increases by 10% to 40% faster than in the rest of the body of the varistor. A varistor with a purpose-built weak point in the structure according to claim 1, characterized in that a weak point (2) of a circular shape with a depth (2a) is intentionally incorporated on the surface of the body (1) of the varistor, so that the surface of the point (2) is in the range 0.05% to 60% of the total surface of the varistor body (1), that the depth (2a) is from 0.1 to 1 mm or 0.1% to 30% of the bodywork (1) varistor. A varistor with a purpose-built weak point in the structure according to claim 1, characterized in that a weak point (3) of a rectangular shape with a depth (3a) is intentionally incorporated on the surface of the body (1) of the varistor, so that the surface of the point (3) in the range 0.05% to 60% of the total surface of the varistor body (1), that the depth (3a) is from 0.1 to 1 mm or 0.1% to 30% of the thickness of the body (1) of the varistor. A varistor with a purpose-built weak point in the structure according to claim 1, characterized in that the weakly placed point (4) at the depth of the varistor body (1) is made by inserting a substance of organic or inorganic origin, which causes the local heating effect according to claim 3. A varistor having a purpose-built weak point in the structure according to any one of claims 1 to 5, characterized in that the targeted embedded weak points are any number. A varistor having a purpose-built weak point in the structure according to any one of claims 1 to 5, characterized in that a weak point is intentionally incorporated in any geometric form. A varistor with a purpose-built weak point in the structure according to any one of claims 1 to 7, characterized in that weak points of different geometric shapes are intentionally incorporated.