Abstract: A fuel cell installation and a method for operating a fuel cell installation with a dynamic power control are provided. The dynamic power control is achieved by additionally connecting at least one subsystem which is kept ready for operation, a starter system and/or a low-voltage unit for nighttime operation and/or an on-board power supply.

Abstract: The device and the method determine the temperature in a fuel cell installation. The temperature is recorded at least at one measurement location, such as a position and/or an region of a fuel cell stack and/or of a fuel cell unit, and is transmitted to a computation unit for a model computation. The computation unit then determines the temperature distribution in the stack with the aid of a model computation and transmits the information to a control unit. The control unit can be used to control the temperature in the stack.

Abstract: The fuel cell installation is operated at temperatures between 80° C. and 300° C. and ensures that the efficiency is optimized, since the waste heat from the fuel cell stack is utilized at least in some other way. For the purpose, there is provided an evaporator upstream of the fuel cell stack. At least one line is connected to the fuel cell stack for rendering available a heat content from at least a part of the fuel cell stack to be utilized in one or more further units of the installation.

Abstract: High-temperature polymer electrolyte membrane (HTM) fuel cells, installations including HTM fuel cells, methods for operating an HTM fuel cell, and an HTM fuel cell installation apply the principle of the known PEM fuel cell and overcomes the major drawback of this fuel cell. By selecting a new electrolyte and changing the operating conditions, in particular the temperature and the pressure, the fuel cells do not depend on water content.

Abstract: In a contact material, there is present in addition to silver, at least one higher melting point metal, metal alloy or metal compound. According to the invention, the material contains in addition to silver (Ag), at least iron (Fe) and/or titanium (Ti) in percent by weight of from 2 to 50%. Optionally, nitrides, carbides and/or borides of the metals titanium, zirconium and/or tantalum may also e present. It has been found that in their contact property spectrum such materials are largely equivalent to the material AgNi10. Thus the latter contact material can be replaced completely.

Abstract: In a known process, oxide powders derived from the four-component systems yttrium-barium-copper-oxygen or lanthanum-strontium-copper-oxygen are mixed, pressed, sintered, ground and then heat-treated to produce a superconducting material which can be shaped to the desired cross-section. According to the invention, the powder is compacted by isostatic pressing and the blank so obtained is extruded at a temperature.gtoreq.500.degree. C. to form a metallic sheath with a deformation ratio of at least 50%. The extruded blank is then converted to wire or strip. The current-carrying capacity of the high-temperature superconductor is improved by the extrusion and the resulting alignment of the crystallites. The process can be implemented using known high-temperatures superconducting material.

Abstract: A method for manufacturing melt materials of copper, chromium, and at least one readily evaporable component as well as a fusible electrode for using this method is disclosed.More specifically, an arc melting method is used for the manufacture of melt materials based on copper and chromium in which the electrode material melting off a fusible electrode of given resultant composition is collected in a water-cooled permanent mold for the purpose of cooling down without macroscopic separation of copper and chromium.A fusible electrode for use in this method is also provided. This fusible electrode partially consists of a solid alloy of copper with the readily evaporable component.

Abstract: This invention relates to a new use of a fused material of copper and chrome as a contact material for use in vacuum contactors. In addition, the invention relates also to the contact material itself and to the method of its fabrication, as well as for special contact arrangements in the vacuum contactors.The invention shows a whole new, unsuspected range of application for the above fused materials. Up to now, contactors normally used material based on tungsten and copper which were first sintered and then immersed. It has now been experimentally shown that fused materials of copper and chrome, particularly after being reshaped, are very well suited as a contact material for vacuum contactors. Furthermore, in contact pieces of said fused material, methods are provided for additional additives to be precisely inserted by localized alloying, diffusion, or related techniques.

Abstract: Contact pieces for vacuum switches with axial magnetic field are designed, for example, as pot type contacts with codirectional slotting which contain in each instance a disk-shaped contact body of contact material and have an arrangement for the suppression of eddy currents. Conventional techniques for this purpose typically involves the cutting of radial slots in the contact bodies. In accordance with the invention, each contact piece (10, 110, 210) comprises a plurality of discrete elements (11, 111, 211) which are so arranged on the concrete carrier (2) that their edges (12, 13; 112, 113; 212, 213) form joints (25, 125, 225) and thereby define conductivity jumps for the suppression of the eddy currents. Specifically the discrete segments (111, 211) are produced by reshaping a cylindrical blank (100) of circular cross section into a semi-finished product of circular sectorial cross section.

Abstract: The invention relates to a material for electrical contacts, in particular for contact studs in low-voltage switchgear. The material consists of silver, tin oxide and other additives. A material is sought where the overtemperature is lowered as compared with known AgSnO.sub.2 material. According to the invention, the further additives are in combination oxides of the metals tantalum (Ta.sub.2 O.sub.5), copper (CuO) and bismuth (Bi.sub.2 O.sub.3). Further the material may contain also tungsten or oxygen containing tungsten compounds. Preferably the material contains 5 to 20 mass % SnO.sub.2, 0.1 to 5 mass % Ta.sub.2 O.sub.5 5 mass % CuO, 0.1 to 5 mass % Bi.sub.2 O.sub.3, optionally 0.05 to 3 mass % tungsten and silver as balance. In the method for producing contact studs, the powder metallurgical production of the material is followed by extrusion to a ribbon, from which contact studs can be separated which have an edge-parallel directional structure.

Abstract: A device for manufacturing a laminated semifinished material by indirect extrusion of a sintered-bond blank consisting of layers of metal, metal alloys, metal mixtures or mixtures of metals and nonmetals comprises a vessel with a rectangular cutout or extrusion chamber and a one- or multipart extrusion die with one or several cutouts. A surface of the die facing the blank is profiled in the form of one or more roof gables, the surfaces of which gable forms extend perpendicularly towards the cutout from a sliding surface of the extrusion die.

Abstract: The ternary-binary conversion is reached by two CMOS inverters dimensioned extremely unsymmetrically with regard to their W/L ratio and connected in parallel at their inputs. By further addition of a NAND or a NOR gate the circuit can be used in an integrated circuit as option releasing stage without additional terminal for the option signal which has only to be chosen as the middle value of the ternary signal whereas its lower and upper values are the binary signals.

Abstract: A keyboard switch matrix has a plurality of column and row wires and switches having only two poles and no interconnecting diodes for selectively connecting one of said columns to one of said rows. Associated with each column and row wire is a flip-flop having a set input connected to the wire and an electronic switch for each flip-flop connecting a flip-flop output to the set input. The outputs of the row flip-flops are connected to a NOR-gate, the output of which is connected to a control input of the electronic switches associated with the column flip-flops and also to a second set input of the column flip-flops. The output of the NOR-gate is further connected to a control input of the electronic switches associated with the row flip-flops through an inverter. Reset inputs of the column flip-flops are connected to the NOR-gate output through a differentiation circuit which is triggered by a negative pulse edge.

Abstract: A method of manufacturing a contact bridge for an electric switching apparatus which contact bridge includes an electrically highly conductive overlay and a concave-shaped support layer. The method comprises the steps of pressing a powder blank comprising two layers of metallic material, one of which comprises iron for the support layer and the other of which comprises copper for the overlay; sintering the blank in a protective gas; sizing the blank; further sintering the blank in a protective gas; further pressing the blank by reverse-flow cup extrusion; and applying an electrical contact to the overlay. Alternatively, the powder blank may comprise a layer of copper-zirconium and silver-metal oxide, the latter for an electrical contact layer. In this embodiment, the contact bridge is formed with the electrical contact in one step and there is no need to apply a contact to the bridge after the pressing by reverse-flow cup extrusion.

Abstract: A circuit arrangement for generating a pulse train having a predetermined first pulse spacing (a) and a second pulse spacing (b) differing from the first by an integral factor greater than one, which pulse spacings are assigned to the binary ZERO and the binary ONE, respectively, dependent upon a predetermined n-bit binary word.