DE1038640B - Self-regenerating evaporation protection - Google Patents

Description

The invention relates to an electrical fuse that operates under the influence of an electrical load interrupts the load current and is also able to after a certain regeneration time to automatically return to the initial state. A device of the type mentioned is used for the most diverse Fields of electrical socket technology are required.

An application example is shown in FIG. 1. In the figure, 1 is an electrical line which is to be interrupted with the aid of switch 2 when a critical isolating current I _{T occurs.} In order to be able to carry out the interruption or the reduction of the isolating current in extremely short times, an auxiliary switch 3 is placed in front of switch 2. A fuse 4 and a parallel resistor 5 are provided in parallel with this. However, the resistance values of the switched-on fuse 4 and of the resistor 5 are so high that, when the switch 3 is closed, the current flowing through the elements 4 and 5 is negligibly small. If, however, the auxiliary peeler 3 - z. B. automatically - opened, the current is first transferred to the fuse 4 and the resistor 5. Because of the considerably greater internal resistance of this element 5, the current flowing through 5 is initially insignificant. Under the influence of the load current, the internal resistance of the fuse 4 increases very quickly to such an extent that the current is completely transferred to the parallel resistor 5. As a result, the current is reduced from the initial value I _{T to} such an extent that a final switch-off by the load switch 2 can take place. In order to keep the arrangement ready for use without replacing the fuse 4, it must be able to automatically reach its initial state, ie its initial internal resistance, again after a short time.

A backup as z. B. is required for the application described above is the subject the invention. The new solution is simple and is characterized by the fact that it is after the Ahsehaltvorgang will surely return to the initial state.

An exemplary embodiment is shown schematically in FIG. 2 shown.

The housing 6, preferably made of glass or some other insulating material, contains the two Rod-shaped electrodes 7 and 8 inserted in a vacuum-tight manner. The housing is evacuated to a high vacuum and fused together in a vacuum-tight manner on the suction nozzle 9.

The electrode 7 consists of a material resistant to mercury, for example iron or molybdenum, and runs at its lower end into a tip 7σ made of high-melting material (WoIf self-regenerating
Evaporation protection

Applicant:

Siemens-Schuckertwerke

Corporation,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Phys. Karl-Georg Günther, Nuremberg,
has been named as the inventor

ram, molybdenum). The electrode 8 is pressed with the housing piston 6 over a cup in the form of a cup Sheet 10 connected in a vacuum-tight manner. The dimensions of the electrodes are chosen so that the Tip of the electrode7 and the deepest point of the bowl

10 are separated from one another by a free gap of small height (preferably 1 to 2 mm). Normally this gap is preferably made up of a liquid, electrically conductive contact bead 11 Mercury, bridged. The fuse element is operationally set up or attached that the contact bead 11 remains held in the position shown under the influence of gravity.

If the fuse is loaded with an electric current of critical strength, the tip 7a of the electrode 7 is heated so much that the metal of the pearl

11 evaporates and thereby an interruption of the contact is brought about. The amount of metal evaporated initially condenses normally evenly on the inner walls of the housing 6. With the help a - preferably electrical - heating device 12, however, the housing wall is heated to such an extent that that a slow re-evaporation of the condensed metal layer begins. The heater

12 is designed and installed so that the entire housing 6 is heated, but the one in the lower one Housing part fused-on sheet metal bowl with the elec-

809 637,373

trode 8 remains unheated. The depression of the cup, which is connected to the air-cooled electrode 8 in direct Contact is, therefore represents the location of the lowest temperature. This has the consequence that from the housing wall 6 slowly re-evaporating amount of metal back at the starting point, namely at the lowest point of the metal cup 10, condensed. After completion of this process, the original starting state is reached again and the securing element can be used again.

By appropriate selection of the heating current passing through the heating device 12, the housing temperature is set preferably brought to a value between 100 and 150 ° C. The temperature in the tip of the bowl moves as a result of the air cooling in the rich between about 40 to 70 ° C. In this way, regeneration times of a few seconds to about 1 minute can be achieved.

If a high switching capacity is not required of the fuse, it is possible to use the heating device 12 normally shut down and only put into operation for a short time after a switching process. this can be carried out automatically, e.g. B. depending on the opening of the auxiliary switch 3 or the Switch 1 or from the current in element 4 and / or 5.

Claims (1)

Claim: Self-regenerating fuse, the two introduced or inserted into a high vacuum vessel Contains electrodes, one of which comprises a metal cup adjoining the vacuum vessel and the other one is brought up to the bottom of the bowl with a point except for a gap and immersed here in an electrically conductive liquid bead, preferably made of mercury, thereby characterized in that a heating device (12) is provided which - at least after the response of the fuse - the walls of the high vacuum vessel (6) heated, the bowl (10) but leaves it unheated. Considered publications:
German Patent No. 172 334;
Austrian Patent No. 72,472;
British Patent Nos. 533 691, 517 719;
U.S. Patent No. 1,858,191. 1 sheet of drawings 1 809 6377373 9.58