When current carrying conductor is wound on the soft iron
piece then a circulating current is produced in it by electromagnetic
induction. Is shape is just like Eddie, so it is called as eddy
current.
This eddy current
produces loss that is called as eddy current loss. This loss produces heat in
the soft iron piece and can be used to heat the material.
Since, the eddy
current loss is proportional to the product of square of supply frequency
and flux density therefore high frequency supply can be utilized to generate
the heat. By controlling the frequency and the flux density the amount of heat
can be controlled.
The articles to be heated are placed within a high frequency
current carrying coil, alternating magnetic field is set up. Eddy currents are induced in the
article and heating is therefore affected.
High frequency current carrying coil is known as magnetic
coil or work coil.
The material, which is to be heated, is known as load or
charge and the process employed is referred to as high frequency eddy current
heating
The eddy current
loss is primarily responsible for the production of heat, but hysteresis loss
also contributes to it, in the magnetic materials.
Induced eddy current is of greatest magnitude at the surface
of the material to be heated and its value decreases with the distance normal
to the surface as we go inside the material.
The supply frequency is employed between 10,000 to 4,00,000
Hz.
