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An alternative harmonic model for representing power system nonlinear loads by a "crossed-frequency" admittance matrix is presented in the paper. This harmonic model is applicable to passive and stationary electrical loads assuming a constant fundamental frequency voltage. Results of the proposed harmonic model are reported and compared with experimental tests.

The behavior of an electromagnetic control valve under a perturbative magnetic field is evaluated. The electromagnetic valve is numerically modeled by means of a nonlinear 2D field-element code. The electromagnetic force produced on the valve's plug is obtained using the Maxwell stress tensor approach, under both normal and perturbed conditions. The numerical results are compared with those of experimental tests, which have been carried out under the same conditions as the numerical analysis. >

The paper, after a brief introduction covering the basic concepts underlying the design of the RFX first wall, describes the main features of the graphite tiles and presents their predicted operating conditions in the presence of applied heat fluxes and electrodynamic forces. On the basis of the results of experimental tests performed to measure the tile-vessel contact conductance, the thermal behaviour is analyzed by means of numerical models which simulate the real operating conditions of the first wall and vacuum vessel, with its forced gas cooling system and its thermal insulation. The safety margin, preventing tile rupture due to electrodynamic extraction forces during fast plasma current terminations, is then investigated by means of mechanical tests closely reproducing the real load distribution. Finally, the stresses due to machining allowances on the tiles and on their grooved seats are analyzed by means of a finite-element model, under the load produced by the bayonet keys which clamp the tiles to the vacuum vessel stiffening rings.