Showing papers by "Grenoble Institute of Technology published in 1978"

Analytical approach to the operation of a synchronous machine associated with a thyristor bridge

Abstract: A synchronous machine associated with a thyristor bridge operates normally under unbalanced conditions which are described and studied in the present paper. Natural cut-off thyristors is used in the present system where the gates of thyristors are controlled by the rotor position. It is assumed that the machine has salient poles and damper windings. Both motor and generator operations are contemplated. An analytical approach has been used, and the exact shape of the currents has been considered. The commutation problem is studied in detail, taking into consideration the transient effects of the armature circuits and the limited value of the smoothing reactor. The different expressions are given in terms of the classical machine constants which can be directly measured or furnished by the manufacturer. Comparison between theoretical and practical results are given.

Local and Instantaneous Measurements in Liquid Metal MHD

Abstract: In liquid metals used for laboratory experiments in magneto-hydrodynamics, such as mercury, the techniques of local and instantaneous measurements are known to be much more delicate than in classical fluids like water and air. Whatever diagnostic method is used, two categories of difficulties must be overcome: those due to the presence of a magnetic field and those due to the nature of the fluid. The former generally appear as fundamental difficulties, since the magnetic field acts like a new parameter which modifies the physics of the measurement apparatus; we will see further on that this can be put to use for imagining new methods which have no equivalent in classical hydrodynamics. The latter appear rather like secondary disturbances which would not exist in perfect experiments and which can (at least theoretically) be reduced by the care taken by the experimenter.