Showing papers by "L.J.M. van de Klundert published in 1985"
TL;DR: In this article, the current distribution between main and auxiliary coils is expressed in terms of geometrical parameters and a method of obtaining a very low auxiliary coil current is suggested to prevent damage to the low-loss superconducting winding by an abnormally high current.
22 citations
TL;DR: In this paper, a magnetically controlled switch element consisting of several Nb1%Zr multifilamentary superconductors is placed between two concentric solenoids which generate the necessary magnetic field.
Abstract: The power of fully superconducting rectifiers can be improved by increasing either the operating frequency or the transformer primary inductance [1]. The frequency is usually limited by the recovery time of thermally controlled switches. In order to achieve a higher switching speed, magnetically controlled switches are preferable [1,2]. This paper describes a magnetically controlled switch which can be used for currents up to 500 A at 25 Hz. The switch element, consisting of several Nb1%Zr multifilamentary superconductors, is placed between two concentric solenoids which generate the necessary magnetic field. The Nb1%Zr superconductor is well suited for this purpose because of its relatively low critical field (≃ 0.75 T) and high maximum current density (about 5.109A/m2below 0.3 T).
10 citations
TL;DR: In this paper, a NbTi multifilamentary wire having a low conductivity matrix was used to prevent eddy currents in order to prevent transport current and a transverse a.c. magnetic field during simultaneous action.
Abstract: A.c. losses caused by an a.c. transport current and a transverse a.c. magnetic field during simultaneous action were measured. The loss contributions have been obtained separately. The measurements were performed on a NbTi multifilamentary wire having a CuNi matrix of low conductivity in order to prevent eddy currents. The test configuration is presented and measurement results as well as theoretical confirmation are dealt with.
8 citations
TL;DR: In this paper, the authors investigated the current carrying capacities of ten NbTi superconductors having a CuNi matrix with diameters between 50 and 300 μm as function of an applied magnetic field of 0 to 6 tesla.
Abstract: We investigated the current carrying capacities of ten NbTi superconductors having a CuNi matrix with diameters between 50 and 300 μm as function of an applied magnetic field of 0 to 6 tesla. The effects of the method of wire fixation and the electrical connections were studied. The results are compared to those obtained with two common conductors with Cu matrix. We observed large differences of a factor 2 between the critical current densities of the various CuNi matrix conductors. Furthermore, it is remarkable that the best CuNi matrix conductors have critical current densities which are much higher than those in Cu matrix conductors.
4 citations
TL;DR: In this article, the authors show that the economic criterion described by Ogasawara and Hlasnik is inaccurate because of an oversimplified hysteresis loss formula, and a necessary modification shows that stricter demands will have to be made.
Abstract: Recent studies confirm the economical feasibility of the application of superconductors in AC power apparatus. The low-loss conductor which has been proposed still only exists in theory. Simple calculations show that the economic criterion described by Ogasawara and Hlasnik is inaccurate because of an oversimplified hysteresis loss formula. A necessary modification shows that stricter demands will have to be made. As production of ultrafine filaments is a big technological problem, final diameter reduction by rolling instead of drawing is proposed. The expected better performance of a rolled composite has been verified experimentally in test coils as well as in transformer geometry. Experimental set-up and results are presented.
1 citations