Channel Type or Direct Core Type Induction Furnace

The direct core type induction furnace is a type of core type electrical heating furnace works at low frequency. It is used to melt metals. The furnace is similar to that of a transformer in which the primary circuit is a winding for electrical supply and the secondary circuit is a single turn
circular hearth which contains the charge to be heated. The two circuits are magnetically coupled but are poorly coupled to one another by an iron core. The heating furnace is in the form of a trough which contains the charge to be melted in the form of an annular ring. Melting is rapid in this type of furnace. Accurate control of temperature can be achieved through this method. Since poor coupling results in high leakage reactance and poor power factor, the furnace is operated at very low frequencies in the order of 10 Hz.

Channel Type or Direct Core Type Induction Furnace

Advantages of Direct Core Type Induction Furnace

1. Rapid melting.
2. Accurate control of the temperature.
3. Clean heating.
4. The furnace inherently has stirring action of the molten material and this result in uniform end material.

Disadvantages of Direct Core Type Induction Furnace

1. Pinch effect – at high current densities the current flowing through the melt will interact with magnetic field of the core and can constrict the cross-section of the molten metal resulting in complete interruption of the secondary circuit.
2. The furnace cannot be started with a solid material as it may open circuit the secondary and requires some molten material to be started but the additional metal can be added once the furnace is heated up. 
3. The furnace is not suitable for intermittent operation since it always requires the molten material.

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