Effect of Supply  Voltage

a.As the applied  as voltage  is increased hysteresis loss increases.

b.Eddy current losses are given by

W e α f² t² B² m

Where B_m =   maximum flux  density in wb /m²

If supply  voltage  is increased flux  due to eddy  current will increase hence  the power  loss will  increase. It means  the  production  of the surface heat  will be  more  if the  applied  voltage is increased.

Induction  heating  is much  superior to electric  resistance heating. In  electric resistance heating the next  of heat transfer is very  less ( l approx 100 w/sq cm or so). However in induction heating  the rate of heat  transfer  can be  as high  as 10000w/sq cm. Because of high  rate  of heating  the rate of production of goods  can be very high moreover the life  of the living  of a high frequency furnace is more  than double  that of  power frequency furnace.  Shows a block  diagram of induction heating . this  complete  system  consist of AC- DC  converter filter and inverter. AC - DC  converter is used to convert 50Hz AC to DC filter is used to  improve the wave shape and inverter is used to give  high  frequency AC.

Induction cooking is  one of the  important  application induction heating. An  electric  or gas cooking  has very  poor efficiency because  appreciable amount of heat is  lost to the  surroundings induction cooking  avoids  this wastage  of heat. Figure shown  a block  diagram  of inaction cooking  rectifiers and filters  are used to  converts 50 Hz AC to smoothened DC an inverter converts this DC into very high frequency  AC which  is then fed to the induction coil. The eddy  currents  in the metal   pan heat the pan and do the cooking.