The working principle of coreless
furnace same as that of core type furnace.
The principle is based on Faraday’s law electromagnetic
induction. Primary winding is connected to the supply and secondary winding is connected
to the load.
Here, load is charged which is to be heated by eddy current
loss
The only difference in coreless
furnace is that the core is absent here. The charge of furnace acts as a
secondary winding.
The two types of constructions are available in case of
coreless furnaces i.e. conducting bottom and non-conducting bottom.
If the container is made up of conducting bottom then charge
may be conducting or non conducting. Since, bottom acts as the secondary.
But if container is made up of some insulating medium then
charge must be conducting one to form the secondary
Conducting container and charge can have either conducting or
non-conducting properties.
Due to primary winding, coils get heated up. Therefore,
cooling arrangement is done by making hollow copper tubing in which cooling
water is circulated
These furnaces require 500 to 1000 Hz frequency supply
The power factor of core
less furnace is very low i.e. 01 lag Therefore, to improve the same, bank
of capacitors is used in parallel with heating coil.
