Adelina Bordianu

Losses analysis for a soft magnetic composite material

The paper aim is to analyze the losses in a soft magnetic composite material. An alternative method to measure the losses is used - the thermal method. The obtained results are presented and is shown that is important to take into consideration the structure and properties of the material if one wants to predict correctly the losses.

QUANTITATIVE ASSESSMENT OF THE EFFECTS OF ELECTROMAGNETIC FIELDS ON THE CREW OF A SHIP ACCORDING TO THE LEGISLATIVE NORMS

Because of the low emitting power of radio stations present on ships, for the specific range of emitting frequencies, parameters such as radiated power density and electric field intensities meet both European and American safety standards (EN 60215: 1989/A2: 1994 Safety Requirements for Radio Transmitting Equipment, En 50371 and FCCs Rule Parts 1. 1310, 2.1091 si 2.1093).The paper presents the limits of the field strength and power density for controlled and uncontrolled environments, for crew exposure, and the limits of field intensities and peak power density.

Noise and Electromagnetic Field Measurements for the Merchant Ship Albatros

Abstract The paper analyses the results of performed measurements regarding the density of electromagnetic power at various points on board a ship, the noise level determined by the operation of certain broadcasting stations and the intensity of the radiated electric field by a station of 250 MHz. We have presented thereby the sources triggering natural and artificial electromagnetic disturbances with their pertaining components.

Measurements for Determining the Efficiency of a Screen of Absorbent Material Used on Board Maritime Vessels

Abstract Screening is one of the main ways to achieve the Electromagnetic Compatibility (EMC) in the electric and electronic devices and equipments onboard a vessel. The present paper analyses the results of certain measurements made in order to determine the screen efficiency from the point of view of damping the induction magnetic field. Starting from the calculus for the screen efficiency, measurements of the intensity and level of the electric field, of the power density, of the damping and of the screening factor were made. These measurements were made both in the presence and in the absence of the screen.

Assessment of the ellipsoidal shell model for ship magnetic signature

There is described and assessed the ellipsoidal shell model for solving the ships magnetic signature. This model relies on the premises of equating the mass of magnetic materials used in the ship hull construction with the mass of material of the ellipsoidal shell. The magnetic field is computed in a horizontal plane situated below the analyzed body, starting from the solution to Laplaces equation formulated in the ellipsoidal coordinate system, and by applying the variable separation method. The field computation is performed in the situations: the external field is parallel to the ellipsoids main axis and perpendicular to it, respectively. The model is analyzed by comparing the computation results to the numerical model constructed in Ansoft Maxwell environment, and, finally, to a set of measurements performed on the actual ship.

Contributions for reducing the magnetic field created by an equipment component of a ship

The paper presents the study of the magnetic signature for a component equipment of the engine sincron generator located on board a ship built from non-magnetic materials. The equipment is analysed in terms of physical and geometrical similarity criteria. The algorithm for computing the electrical circuits from the global compensation windings was correlated with the ships geometrical shape. In was taken into consideration the fact that the winding arrangement is symmetrical to the ship diametrical plan, as well as the ship magnetic field. The paper purpose is to realise the equipment permanent and inductive magnetization compensation.

Numerical testing of homogenization formulas efficiency for magnetic composite materials

Magnetic composite materials are used for multiple applications. The macroscopic behavior of the material is influenced by its microscopic properties. Sometimes it is difficult to model the complex structure of the composite because the properties differ at the microscopic scale. Some simplifying assumptions are often needed, one of them being the homogenization of the material. In this paper two different composite materials were analyzed using a finite element software (COMSOL Multiphysics©). Both materials have a non-magnetic matrix with inclusions made of paramagnetic material for one of them, and ferromagnetic material for the other. The 3D numerical simulations were made for different particle concentrations and for different applied fields. The homogenization was implemented using two different formulas: Maxwell Garnett and Bruggeman. Numerical comparison was made between the magnetic properties of non-homogeneous materials and homogeneous ones showing each formulas efficiency for different cases.

Analysis of magnetic fields generated by conical coils

The purpose of the paper is to find the optimal conical coil geometry in order to obtain a high magnetic field under the cone, which can be used to magnetize a magnetic sheet. The optimization was performed both in the presence and in the absence of the magnetic sheet.

Magnetic losses estimation for non sinusoidal current supply

The effect of current harmonics inside equipment containing magnetic materials is analyzed by computing the magnetic losses of the magnetic cores having hysteresis. Some typical variable speed drives and remedial techniques for reducing the harmonics are considered, the magnetic losses estimation including the Preisach hysteresis model. The results show the supplementary losses produced by harmonics and the necessity to reduce them.