In this article we will discuss about:- 1. Meaning of Eddy Current Heating 2. Advantages of Eddy Current Heating 3. Disadvantages.
Meaning of Eddy Current Heating:
Eddy current heating is also known as the induction heating. The material to be heated is placed inside the coil. The heat in the material to be heated is produced by eddy currents. Power loss due to eddy currents is eddy current loss and appears in the form of heat.
The metal to be heated is placed within a high frequency current carrying coil. By doing so alternating magnetic field is set up, eddy currents are induced in the metal piece and heating is affected. The power loss due to eddy current in the metal piece depends upon the power drawn by the metal piece.
The eddy current loss,
where Bmax = Maximum flux density
f = Supply frequency
ρ = Resistivity of metal piece
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Since the eddy current loss is proportional to the product of square of supply frequency and square of flux density, therefore by controlling the flux density and supply frequency the amount of heat can be controlled.
The frequency may vary from 50 Hz to 8 MHz depending upon the type of work done.
This method is frequently used for forging, annealing. The process is economical for continuous heating.
Advantages of Eddy Current Heating:
(1) It is quick, and clear.
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(2) There is little wastage of heat as heat is produced in the body to be heated up directly.
(3) Temperature control is easy i.e. by controlling the supply frequency and flux density.
(4) The heat can be made to penetrate into the metal surface to any desired depth.
(5) The equipment can be operated even by unskilled worker.
Disadvantages of Eddy Current Heating:
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1. It is costly method for the production of heat.
2. Low efficiency.
3. Initial cost of apparatus is high.