US2618765A

US2618765A - Excess voltage grounding device

Info

Publication number: US2618765A
Application number: US209688A
Authority: US
Inventors: Vogelsanger Ernst
Original assignee: Werkzeugmaschinenfabrik Oerlikon Buhrle AG
Current assignee: Rheinmetall Air Defence AG; Maschinenfabrik Oerlikon AG
Priority date: 1950-05-20
Filing date: 1951-02-06
Publication date: 1952-11-18
Anticipated expiration: 1969-11-18

Description

NOV. 18, 1952 VQGELSANGER 2,618,765

EXCESS VOLTAGE GROUNDING DEVICE Filed Feb. 6 1951 Fig. 1

7 Ea 1 155; F 1 INVENTOR.

\ VageZsanye/t Patented Nov. 18, 1952 EXCESS VOLTAGE GROUNDING DEVI-CE Ernst Vogelsanger, Zurich, Switzerland, assignor to Ateliers dc Construction Oerlikon, Zurich- Oerlikon, Switzerland, a corporation of Switzerland Application February 6, 1951, Serial No. 209,688 In Switzerland May 20, 1950 8 Claims.

Excess voltage grounding devices or lighting arresters consist generally of a non-linear resistance and a spark gap. Both the resistance and the spark gap are composed of elements which are built up to form a column. In order to keep the height of the column as low as possible the elements of the spark gap may be arranged next to the resistance elements or concentrically within annular resistance elements.

Fig. 1 of the attached diagrammatic drawing shows for example a part of such a grounding device. The resistance elements i are stacked with insulating intermediate layers 2; between each two resistance elements a spark gap element 3 is connected. In such arrangement there is formed between the near electrodes or

terminals

4 and 5 of each two adjacent resistance elements a capacitance C, which in each case bridges or shunts the sparking gap element 3. Such capacitance presents a great disadvantage in the function of the lighting arrester, because when a surge voltage wave appears, the charging current or the capacity fiows across the resistance elements producing there a voltage drop which increases the operating voltage of the lighting arrester.

Such disadvantage is eliminated according to the present invention by arranging in the insulating intermediate layer between each two resistance elements a condenser element consisting of a conducting layer that is so connected to the opposite electrode, 1. e., far terminal of one of the resistances that the capacitance bridging the sparking gap is diminished, and the capacitance bridging the resistance is increased.

Fig. 2 shows by way of example two elements of a lighting arrestor of the present invention. Within the insulatin intermediate layer 2 there is arranged a conductive plate or layer 6 which is electrically connected to the far terminal 4 of the upper resistance element 1. In lieu of the harmful capacitance C there now appear two useful capacitances C1 and C2, one of which (01) bridges the resistance element 1 and the other (C2) bridges the entire combination of resistance element I and sparking gap 3. On the appearance of surge voltage wave the former decreases the voltage drop in the resistance element I, the latter produces a uniform voltage distribution through the elements I and 3 stacked on each other. Fig. 3 shows the equivalent electrical diagram of this arrangement.

In the example shown in Fig. 2 each insulating intermediary layer 2 between the resistance elements I consists of resin capable of being cast. The spark gap element 3 is likewise embedded in such casting resin and united with the intermediate layer of insulation to form a unitary casting. -IIowever, the invention extends also to other arrangements. For example Fig. 4 shows an embodiment in which the resistance elements I are separated by two ceramic bodies I acting as condensers between which the conductive layer 6 is arranged. Here the high dielectric constant attainable with ceramic material (e. g., 190 up to several thousands) are used to obtain great values of capacitances C1 and C2. The same purpose is attained also if, in the embodiment shown in Fig. 2, ceramic material with a high dielectric constant (e. g., and higher) is cast in pouring resin, for example, in the form of tablets inserted between the electrode 4 and the layer 6, or for instance between the electrode 5 and the layer 6, or in the form of a granular filler.

Having thus explained my invention, I claim:

1. A lighting arrester comprising the combination with a stack composed of at least two nonlinear resistance elements with at least one insulating intermediate layer located therebetween, and spark ap elements connected between such two resistance elements, such spark gap elements being connected to the opposite near terminals of such resistance elements separated by the corresponding insulating intermediate layer, forming in case of a high voltage surge an undesirable capacitance bridging the spark gap elements between such terminals; of means acting to diminish such capacitance in such case, which comprises a condenser element consisting of a conductive layer disposed between said resistance elements, and means electrically connecting said condenser element to the far terminal of one of such resistance elements, thereby in case of a high Voltage surge providing a capacitance bridging the resistance element, and simultaneously providing a capacitance bridging the series combination of such spark gap and resistance elements.

2. A lighting arrester as defined by claim 1, in which the insulating intermediate layer consists of casting resin with a condenser element cast therein.

3. A lighting arrester as defined by claim 2, in which the spark gap elements are mounted on said layer of casting resin.

4. A lighting arrester as defined by claim I, in which two insulating layers are disposed between the near poles of each pair of adjacent resistance elements, at least one of said layers being composed of a ceramic member having a dielectric constant of at least 100, and the condenser element is disposed between said ceramic members.

5. A lighting arrester as defined by claim 2, in which said layer of casting resin also contains at least one internal layer composed of ceramic material having a dielectric constant of at least 100 disposed between said condenser element and one of the resistance elements.

6. A lighting arrester as defined by claim 2, in which such casting resin contains a filler with a dielectric constant of at least 100.

'7. In a high voltage surge arrester comprising a stack of non-linear resistors, and insulators separating such resistors, and spark gaps in series with the terminals of pair of such resistors which are separated by said insulators; condenser elements disposed in said insulators between said terminals, and conductors electrically connecting said elements to the far terminals of corresponding ones of said resistors, providing a series of capacitances between each condenser element and the near terminals ofeach pair'of resistors, which efiectively diminishes the capacitance between the latter in the eventof a high voltage surge, and at, the same time provides an increase of the capacitance which bridges each resistor.

8. A lighting arrester subcombination comprising a tubular resistor, an annular insulator contacting one end of said resistor, spark gap elements mounted within saidinsulator, an annular condenser element carried by said insulator in substantially parallel relation to'said end of the resistor, a conductor connecting said condenser element to the far end of said resistor, a conductorconne'cting the near end of said resistor to one end of said spark gap elements, and a conductor connecting the'other end of said spark gap ele'nients'to' a 'terminal on the face of said insulator opposite said resistor.

ERNST VOGELSANGER.

REFERENCES CITED Ihe following references are of record in the file of this patent:

Olsen June 24, 19477