Last years, authors developed a four parameters arc model before current zero, considering a linear dependency of the cooling power and of arc time constant on the module of arc current. The model was in enough good agreement with the synthetic test data records during the last 8-10 microseconds before current zero, obtained in Praha HPL and the new introduced parameters of switching devices was determined to fit better the experimental data. To

The diffusion of suddenly occurring local high temperature in homogeneous half-infinite space is studied in the cases of one, two and threedimensional half space. Comparison of the three cases is made. Applications of theoretically analyzed models are suggested. Errors induced by assumptions are evaluated.

The field modelling becomes simpler if strong field nonuniformities are solved theoretically. The early-obtained formulas for 2-D "corner" permeances, (capacitances or resistances) pertain to right angle configurations. In this paper, using a conformal mapping and analytical approximations, the field in the vicinity of arbitrary angle corner is studied and the corner resistance determined. Obtained results can be applied to a large range of electromagnetic

Field modeling becomes simpler if strong field nonuniformities are solved theoretically. The early obtained formulas for 2-D “corner” and “constriction” permeances pertain to right angle configurations. In this paper, using a conformal mapping, the field in the vicinity of arbitrary angle vertex is studied and the fringing permeance determined. The results are applied to permeance evaluation of lunate cross section grooves from the rotors

By solving the ecuations of magnetic field in the slot with uniform saturated lateral sides ( i = const.), for constant current-density in conductor cross-section, one obtain a formula for the specific leakage inductance of the coil. The curves of inductance for equal air-gaps and not saturated shaded part of pole are given.

Using an analytical expression for arc voltage before the voltage maximum and considering a linearly decreasing current, a method for the evaluation of defining model parameters, from oscillograms obtained from synthetic tests, is described. The initial values, taken from oscillograms are: the current slope and the linear current at voltage zero, the maximum voltage with the corresponded time and the voltage and time at the beginning of the oscillogram.

By using a conformal mapping, the variation of the electric or magnetic field in gaps near a corner is studied, and some formulas for two-dimensional (2-D) “corner” and “constriction” permeances are proposed. The formulas offer the possibility of making more accurate analytical calculations of magnetic circuits and to better evaluate magnetic forces acting in plunger magnets

The known formulas for 2D "corner" and "constriction” permeances have been derived by using conformal mappings for infinite domains and can be applied only for enough large domains. In this paper, the problem is analytically solved for finite domains and new exact and approximate formulas are proposed. It is shown that for finite domains the corner and constriction permeances can be much smaller than in the case of infinite dimensions and the limits

Abstract * A new method - the power approximation of boundary conditions in connected regions - is used to solve the two-dimensional magnetic field problem within the window and the gap of the magnet, considering the core uniform saturated. Expressions of inductance and magnetic flux are given.