Page 275 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

An induction heater looks like any other ceramic cooktop, with different zones for placing pans and pots of varying
sizes. It consists of a tough, heat-resistant glass-ceramic plate on which the user places pots and pans that
need to be heated. Directly underneath the plate there is an electromagnetic coil of metal that is electronically
controlled. This is the main component responsible for heating the vessels kept above the heater.
When you switch on the power supply of the heater, an electric current passes through the coil. The electric
current passing through the coil produces a magnetic field in all directions around the coil, including directly above
it (where pots and pans are placed). (Fig 3) Note that until this point, no heat is generated, as the magnetic field
being produced doesn’t produce any heat unless a third object - the cooking pan - is introduced into the mix.
When a heater pan (made of a suitable material) is placed on the cooktop, the magnetic field produced by the coil
penetrates the metal of the pan too. This fluctuating magnetic field now causes an electric current to flow through
the material of the pan too. The current ‘induced’ on the surface of the pan in this way is called an eddy current,
which is different from the electric current flowing through wires. Eddy currents are actually loops of electric
current that are induced in a metallic field due to a changing magnetic field nearby.
This induced current travels around the metallic structure of the pan, dissipating some of its energy in the form of
heat. This is the heat that raises the temperature of the pan placed on the cooktop and cooks the food inside the
pan by heat transfer through conduction and convection.
Advantages and disadvantages of induction heater
1 Induction heaters are very energy-efficient, in that they transfer most of the energy to the cooking pan with
minimal loss of energy. (Fig 4)

Fig 3 Fig 4

2 Also, induction cooktops heat stuff up very quickly, unlike regular stoves, which lose a great deal of energy to
their surroundings.
3 They are also pretty easy to clean and operate and safe to use.
Disadvantages
A major drawback of induction heater is that they only work with pans and pots that are ‘compatible’ with them.
The containers and vessels placed on the cooktop should contain iron in some form (e.g., stainless steel), as
it’s the only metal that efficiently produces eddy currents and generates heat through magnetic fields. Therefore,
glass, aluminium and copper cookware cannot be used on induction heater.
In a nutshell, using an induction heater is a smart thing to do if you care about electrical efficiency, speedy heating,
better cooking control and higher levels of safety. As for the suitability of your existing cookware for induction
cooktops, just try sticking a magnet to them. If it sticks, then the pan/pot is fit to be used.

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CITS : Power - Electrician & Wireman - Lesson 101-103