ABB Ltd

About: ABB Ltd is a company organization based out in Zurich, Switzerland. It is known for research contribution in the topics: Voltage & Signal. The organization has 6222 authors who have published 6852 publications receiving 83994 citations.

Method of producing a mixed metal oxide powder and mixed metal oxide powder produced according to the method

Abstract: A mixed metal oxide powder of nominal composition Mx M'x ' . . . , Oz, wherein M, M', . . . are metal elements and each of x, x', . . . z is greater than zero, is produced by forming an aqueous solution comprising metal salts such that the solution contains at least some of the metal elements of the mixed metal oxide in a desired ratio and comprises at least one oxidizing agent such as a nitrate of one of the metals, and at least one reducing agent such as an organic acid. The oxidizing and the reducing agent as well as the ratio of the former to the latter are chosen such that the thus-formed tuned solution undergoes an exothermic reaction occurs at a desired rate and at a desired small temperature range. Aerosol-droplets of essentially equal dimensions are generated from the tuned solution and are sprayed into a heated gas jet. The temperature of the gas jet and the residential time of the droplets in the gas jet are chosen such that the exothermic reaction and that the material of the mixed metal oxide powder is formed into an essentially amorphous oxide phase. Mixed metal oxide powder manufactured according to this method can be used in a sintering process for forming any high performance ceramics, in particular a metal oxide varistor with an excellent homogeneity, a high breakdown voltage and a low protection factor.

Arrangement for reduction of acoustinc vibrations in a combustion chamber

Abstract: The invention refers to a combustion chamber device including a combustion chamber ( 2 ) and a set of burners ( 6 ) with an outlet opening ( 7 ) in the combustion chamber. Each burner includes members ( 10 ) for the supply of a flow of oxygen-containing gas, members ( 8 ) for the supply of fuel, and a space ( 9 ), which extends to the combustion chamber ( 2 ) for mixing of the fuel and the oxygen-containing gas. Each burner ( 6 ) is arranged to convey a substantially equally large flow of oxygen-containing gas through the burner to the combustion chamber. Each burner ( 6 ) is defined by at least one parameter including a characteristic length (a) of the space ( 9 ) along the longitudinal direction (x). At least the characteristic length (a) of at least one of the burners is selected in such a way that it deviates from the corresponding length (a) of another burner and in such a way that the influence of the oscillations which arise during operation of the combustion chamber device are reduced.

Switching device including spark gap for switching electrical power

Abstract: A device for switching electric power comprises at least one electric switching arrangement (5). This switching arrangement comprises at least one switching element (10a) comprising an electrode gap (24). This gap is convertible between an electrically substantially insulating state and an electrically conducting state. Furthermore, the switching element comprises means (25) for causing or at least initiating the electrode gap or at least a part thereof to assume electrical conductivity. The means (25) for causing or at least initiating the electrode gap to assume conductivity are adapted to supply energy to the electrode gap in the form of radiation energy to bring the gap or at least a part thereof to the form of a plasma by means of this radiation energy.

Hybrid HVDC breaker - Technology and applications in point-to-point connections and DC grids

Abstract: SUMMARY This paper presents the Hybrid HVDC breaker concept and the achievements in its implementation. HVDC breakers are essential building blocks for selective protection and thus system stability in HVDC networks. If an HVDC grid is built without fast-acting breakers capable of interrupting and isolating DC faults, the DC system voltage will quickly collapse in the event of a fault and the effects of the fault will propagate very quickly throughout the network due to low impedance of the DC network. Beyond enabling DC grids, HVDC breakers can improve the stability and availability of AC grids connected to point-to-point HVDC transmission systems. In case of DC failures, the converter stations can be quickly isolated from the faulty DC side, thus continuing to stabilize the AC grid by generating or absorbing reactive power. This paper contains a detailed description of the Hybrid HVDC breaker, its control and design principles with focus on reliability. The results from functionality and failure tests on the prototype will be presented. The paper also summarizes the test results of its main components such as the semiconductor modules and the ultra-fast disconnector. The results show that the Hybrid HVDC breaker is a feasible concept ready to be used in future HVDC systems. Through a sectionalized design using breaker cells a controlled current limitation as well as dc-voltage post-fault recovery is demonstrated. The handling of dc-faults in point-to-point dc-overhead line transmission is discussed enabling fast fault clearing action while providing continuous reactive power support. The HVDCbreaker thereby significantly boosts the capability and functionality of dc-circuit protection in order to enable a flexible future expansion of point-to-point transmission into multi-terminal or meshed configuration.

Hot-electron transport through thin dielectric films: Boltzmann theory and electron spectroscopy

Abstract: The transport problem of hot quasifree electrons through thin planar dielectric films of thickness d is considered by solving the steady-state Boltzmann equation for the electron current density J(E,\ensuremath{\mu},x), 0\ensuremath{\le}x\ensuremath{\le}d, within the film. The current density of injected electrons at x=0, ${J}^{(i)}$(E,\ensuremath{\mu}), evolves to J(E,\ensuremath{\mu},d), the current density of electrons escaping the layer at x=d, which is calculated.In our approach, electron transport is assumed to be controlled simultaneously by energy-dependent elastic and inelastic scattering with scattering rates ${\ensuremath{\gamma}}^{\mathrm{el}(\mathrm{E})}$ and ${\ensuremath{\gamma}}^{\mathrm{inel}(\mathrm{E})}$, respectively. For inelastic scattering, one single inelastic scattering process with energy loss \ensuremath{\Delta}E is assumed. With this assumption, the Boltzmann equation transforms into a set of coupled integro-differential equations which describe the cascading down of hot electrons in discrete energy steps \ensuremath{\Delta}E during solid-state transport. The resulting cascade problem is then solved analytically in the two-flux approximation. The transport of zero-energy-loss electrons in the topmost energy interval \ensuremath{\Delta}E at the maximum energy ${E}_{0}$ is considered separately. In this interval, no in-scattering from higher energies occurs and the Boltzmann equation for J(${E}_{0}$,\ensuremath{\mu},x) becomes energy decoupled. An exact formal solution of the zero-energy-loss transport problem is presented and exact and approximate results for the two limiting cases of pure elastic and pure inelastic scattering are compared. Our theoretical results are then applied to typical electron transmission experiments such as internal photoemission for transport analysis (IPTA), low-energy electron transmission (LEET), and x-ray photoelectron spectroscopy (XPS) in the substrate-overlayer configuration.It is shown that energy-dependent elastic and inelastic scattering rates in wide-band-gap insulators can be extracted from IPTA and LEET experiments with our theoretical analysis. Using these results, the experimentally determined J(E,\ensuremath{\mu},d) can be reconstructed. Our analysis also allows for a rigorous definition of XPS escape lengths in terms of scattering rates.