SU725110A1 - Heavy-current cutt-off device - Google Patents

Description

one

The invention relates to high current switches. The fast switching off of high currents is of great interest for high-power inductive energy storage devices used, for example, to power pulsed electron accelerators, lasers, and high-temperature plasma installations.

The prototype of the invention is device 1, which between the massive conductors, to which the interrupted current is supplied, is fixed thin conductors in the form of a set of wires or fouls placed in a dielectric medium; In known devices, the thickness of the conductor is chosen from the condition that an explosive conductor explodes at operating current densities, and is usually 10 cm. Inert materials such as sand (ABO3), polymers are used as dielectrics. This reduces the possibility of breakdown due to collisions of electrons with gas molecules forming from a dielectric and with the channel walls that form when a conductor explodes in a dielectric.

This improvement reduces the likelihood of breakdown during switching, but does not completely reduce, but rather increases the energy loss in the switch,

since together with the explosion of the conductor, energy is expended on heating, destruction and evaporation of a part of the dielectric.

The purpose of the invention is to reduce the loss of electrical energy and increase the breakdown voltage of a switch consisting of a conductor placed in a dielectric.

This goal is achieved by the fact that the conductor is made in the form of a set of films separated by dielectric layers

 -, where t - current breaking time, au -

the rate of propagation of the metal burning reaction. As materials of conductors and dielectrics, components of pyrotechnic compositions can be used. Aluminum was chosen as the conductor material, and sulfur as the dielectric material.

The drawing shows a diagram of the device for switching off the current.

Between the massive conductors 1, to which the interrupted current is supplied, the conductors 2 are fixed in the form of a set of thin films separated by layers of dielectric 3. The parameters and mode are selected so that when heated by a current, the conductor quickly enters into a chemical reaction with a dielectric. In this case, the volume.

occupied by the conductor, is quickly filled with non-conducting reaction products that prevent electrical breakdown. In this case, the electrical energy is spent only to heat the metal and the adjacent thin dielectric layer to the temperature of initiation of the reaction; the further reaction is supported by its own heat generation,

An example of a device implementation is a switch in which sheets of thin aluminum platens are compressed with iron oxides. A chemical reaction that can be carried out in such a system is similar to the reaction that occurs during the combustion of typical pyrotechnic compositions, termites, consisting of pressed mixtures of fine powders of metals and oxides. The reaction is reduced to the oxidation of the active metal by the oxygen of the oxide of the less active metal. The reaction conditions are selected such (excess oxide) so that as a result of an incomplete reaction, mixtures of metal oxides are formed — poorly conducting slags. Examples of possible pyrotechnic mixtures to be used for these purposes are: lime systems: (FezOa, A1), (MnOg, A1), (CrgOz, A1), (S, A1), (Si02, M), (Zr, BaSg04) .

The burning rate of these systems is approximately in the order of 1 cm / s. Therefore, in order for a current to break through the chemical reaction quickly enough, the conductor must be in a finely dispersed state. For example, in order to provide a current rupture time of 10-10 s, the characteristic size of the conductor should be

  10-100 A. For creating a comm

For large currents, it is necessary to have a relatively small impedance of conductors entering the switch. In order to reduce the size of structures, the switch should consist of. alternating conductor (fuel) films with thickness b and a dielectric (oxidizer). The impedance of parallel-connected conductor layers is chosen small enough so that at the maximum current used, no pure electrical conductor explosion occurs. The dielectric films should be approximately the same size as the metal to ensure a sufficiently complete transition of the metal to the dielectric during a chemical reaction of a metal heated with a current. To ensure

The mechanical strength of the switch thickness of the oxidizer films can significantly exceed the thickness of the metal films. At the same time, however, the transverse dimensions and electric energy losses increase due to the conductor preheating to the temperature of initiating a fast chemical reaction due to the large heat sink from the conductor to the dielectric. Needed. A composite conductor comprising a set of alternating thin conductive and insulating layers arranged along the direction of current flow can be made by successive sputtering of layers of metal and dielectric. In this case, the metal spraying mask should have a slightly larger longitudinal dimension as compared to the dielectric spraying mask so that metal contacts are formed at the ends, providing connections with all the conductive layers.

Thus, the choice of materials, dimensions and arrangement of the elements of conductors and dielectric makes it possible to create a switch of strong electric current with a higher breakdown voltage than the known designs and with a smaller amount of electric energy loss.

Claims (2)

1. A device for switching off high currents consisting of a set of conductors placed in a dielectric medium, characterized in that, in order to reduce electric energy lost in the switch and to prevent electrical breakdown across the switch at the moment of shutdown, the conductor is made as a set of separated layers mi dielectric ples thick where t is the break time V current (10 - IQ-SC) and and - the rate of propagation of the metal burning reaction (10 cm / s), and components of pyrotechnic compositions are used as materials of conductors and dielectrics. 2. A device according to claim 1, characterized in that aluminum is used as the material of the conductor, and sulfur is used as the material of the dielectric. Sources of information taken into account in the examination 1. Mezonier, Lienhart and Gurlen. Instruments for Scientific Research, No. 10, 96, 196fi.