Field sources in Transient magnetics
The field sources can be specified in blocks, at the edges or at the individual vertices of the model. Possible field sources include space, surface and linear electric currents, voltages applied to conductive areas, and permanent magnets. The coercive force is chosen to be primary characteristic for the permanent magnets.
A point source in the xy-plane describes a linear current in out-of-plane direction. In axisymmetric case the point source represents the current in a thin ring around the axis of symmetry. Edge-bound source in the plane of model represents a surface current in three-dimensional world. It is specified by the Neumann boundary conditions for the edge.
The space-distributed current is defined differently in areas, where the eddy current effect is considered (non-zero conductivity is specified) or not considered (conductivity is set to zero). In latter case, the space current is described either by the electric current density or total number of ampere-turns associated with the block density associated with the block. Current density in a coil can be obtained from the equation
j = n·I / S,
where n is a number of turns, I is a total current, and S is a cross-sectional area of the coil.
Several blocks with the same number of ampere-turns specified can be considered as connected in series. In that case current density in each block would be calculated as common total ampere-turns divided by the square of the block.
In axisymmetric case if total number of ampere-turns is specified resulting current density could be described as varies as 1/r, where r is a radius coordinate of the point. This approach allows simulate massive spiral coils.
In a massive conductor, you specify a voltage applied to the conductor. In planar problems, voltage drop is specified per 1 meter depth of the model, and in axisymmetric case voltage is assumed per one turn around the axis of symmetry. Nonzero voltage applied to a conductor in axisymmetric problem means that the conductor has a radial cut, and the voltage is applied to sides of the cut. In practice this option could be used to describe known voltage applied to massive spiral wiring, in which case the total voltage drop for the coil should be divided by number of turns in the coil. Zero voltage means that the conductor's ends are short circuit.
Voltage, current, or the current density can be specified as arbitrary function of time. This allows you to perform analysis of any possible type of time-varying sources - periodic or not.