1. Mr. Vijay Balu Raskar - Electrical Engineer
DIELECTRIC HEATING
Mr. Vijay Balu Raskar - Electrical Engineer

2. Mr. Vijay Balu Raskar - Electrical Engineer
When a solid dielectric material (Insulating) is subjected to an alternating electric field , it is not supposed to carry any current. However, in practice some leakage current passes through it and power loss is takes place. This loss is called as dielectric loss and result into heating of dielectric material.
Mr. Vijay Balu Raskar - Electrical Engineer

3. APPLICATION OF DIELECTRIC HEATING
Plywood Industry
Sand Core Baking
Plastic Industry
Tobacco Industry
Bakeries
Electronic Sawing
Dehydration of food
Electro medical application
Book Binding
Mr. Vijay Balu Raskar - Electrical Engineer

4. Mr. Vijay Balu Raskar - Electrical Engineer
Advantages of Dielectric heating 1) Heating is very quick 2) The efficiency is higher 3) Heating is uniform 4) Being free from smoke, dust, process is very clean 5) There are no flue gases, no risk of pollution 6) Heat is produced due to dielectric loss occurs in the material itself
Mr. Vijay Balu Raskar - Electrical Engineer

5. Mr. Vijay Balu Raskar - Electrical Engineer
ARC HEATING
One of the popular method of heating.
Principle:- When voltage is applied between the two electrodes separated by small distance in air is increased, a stage is reached when the air gets ionized and air act like conducting. Hence, current flows between the electrodes in the form of continuous spark called ARC. This self sustained discharge of electricity between 2 electrodes through air is known as “Electric ARC”.
Mr. Vijay Balu Raskar - Electrical Engineer

6. Mr. Vijay Balu Raskar - Electrical Engineer
An ARC drawn between 2 electrodes has a temperature between 3000 C to 3500 C depending upon the electrode material. ARC Heating Types:- 1) Direct ARC heating 2) Indirect ARC heating
Mr. Vijay Balu Raskar - Electrical Engineer

7. Mr. Vijay Balu Raskar - Electrical Engineer
Direct ARC Furnance
Mr. Vijay Balu Raskar - Electrical Engineer

8. Mr. Vijay Balu Raskar - Electrical Engineer
Direct ARC :- ARC is established between the charge and the electrode. The heat is directly conducted to the charge which charge absorb. Hence, this method is called Direct ARC heating. This consist of Carbon or Graphite electrode. The power is controlled by adjusting the ARC length by moving the electrodes manually or automatically.
Mr. Vijay Balu Raskar - Electrical Engineer

9. Mr. Vijay Balu Raskar - Electrical Engineer
USE (Direct ARC) 1) Making of Alloy steels like stainless and high speed steel 2) Composition can be controlled during refining process. Direct ARC operates at 0.8 p.f. Lagging
Mr. Vijay Balu Raskar - Electrical Engineer

10. Mr. Vijay Balu Raskar - Electrical Engineer
INDIRECT ARC:
Mr. Vijay Balu Raskar - Electrical Engineer

11. Mr. Vijay Balu Raskar - Electrical Engineer
INDIRECT ARC: ARC is formed between two electrodes and heat is transmitted to the charge by radiation. Lower temperature than direct ARC. It Operates at 0.85 p.f. lagging have to provide rocking motion through a motor to distribute heat uniformly. USE:- melting non-ferrous metals.
Mr. Vijay Balu Raskar - Electrical Engineer

12. Mr. Vijay Balu Raskar - Electrical Engineer
Due to application of sufficiently high voltage across an air gap causes the air in the gap to get ionized and forms ARC ARC drawn between two electrodes develop high temperature ( °C)depending upon material ARC may be used in following ways: by striking between charge and electrodes-principle behind Direct ARC Furnace by striking between two electrodes principle behind Indirect ARC Furnace by striking between an electrode and the two metallic pieces to be joined -principle behind ARC welding
Mr. Vijay Balu Raskar - Electrical Engineer

13. Mr. Vijay Balu Raskar - Electrical Engineer
Principle of transformers
In the transformer, supply is utilized by secondary.
Mr. Vijay Balu Raskar - Electrical Engineer

14. Mr. Vijay Balu Raskar - Electrical Engineer
Induction method is based on Principle of “Electromagnetic Induction”
When alternating Current flows in a conductor it produces alternating flux.
If any other conducting material is placed in this magnetic flux emf gets induced in it
This induced emf drives eddy current in that piece and power loss due to eddy current appears as heat.
Mr. Vijay Balu Raskar - Electrical Engineer

15. Mr. Vijay Balu Raskar - Electrical Engineer
Factors for Induction heating:- 1) it is proportional to relative permeability. Heating produced in magnetic material is more than non magnetic material. 2) Heating is proportional to MMF. Force can be vary by changing current or number of turns. 3) Heating effect can be increased by employing high frequency supply.
Mr. Vijay Balu Raskar - Electrical Engineer

16. DIRECT INDUCTION HEATING
In this, currents are induced in the charge itself. This is usually used in furnaces for melting (extraction of metal from ore), melting of metals etc.
This requires very high frequency supply.
They are classified as core and coreless type induction furnaces.
Mr. Vijay Balu Raskar - Electrical Engineer

17. INDIRECT INDUCTION HEATING (Example :- Oven)
In this, eddy currents are induced in the heating element.
Thus heat produced by heating element is then transferred to the charge by radiation or convection.
Mr. Vijay Balu Raskar - Electrical Engineer

18. Advantages:- Limitations:- Applications:-
Simple and foolproof method of temperature control
No external temperature control equipments required
Poor Power factor
Complicated Construction
It is used for general heat treatment of metallic and other charges.
Mr. Vijay Balu Raskar - Electrical Engineer

19. Mr. Vijay Balu Raskar - Electrical Engineer