Notch effect of the magnetizer
A copper conductor of rectangular cross section is placed in the notch of the magnetizer stacked by the silicon steel sheet. When the conductor is connected with an alternating current, the current will flow only through the conductor surface layer at the opening of the magnetizer. The phenomenon is called the notch effect of the magnetizer or the trending effect of the magnetizer.
The silicon steel sheet is a high magnetic permeability material , and its relative magnetic permeability is up to μr=7500 , far exceeding the relative magnetic permeability of copper and air , so the magnetic resistance is small , and the magnetic lines of force are forced to pass through the magnetizer , as shown in the figure . The bottom of the notch passes through all the magnetic lines of force . In the notch and at the notch , a part of the magnetic lines of force is closed through the copper conductor , and a part is closed through the air . Obviously , the magnetic lines of force distributed so that the conductors at the bottom of the slot are interlinked with more magnetic flux , resulting in a larger self-induced electromotive force , which is equivalent to an increase in the impedance of the conductor and a natural decrease in current . The conductor at the upper part of the notch only crosses the magnetic field lines of the air , and the flux of the interlinkage is small , so the self-induced electromotive force is also small , which is equivalent to the decrease of the conductor impedance and the natural increase of the current .
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The deeper the slot depth of the magnetizer and the higher the current frequency, the stronger the notch effect of the magnetizer.
The notch effect of the magnetizer can be used to drive the current in the conductor to the surface of any part of the conductor to improve the heating efficiency of the inductor. induction heater.The U-shaped silicon steels sheet magnet guide groove is outwardly applied to the ring conductor to overcome the ring effect of the conductor and drive the current to the outer surface of the ring conductor. This inductor is used to strengthen the adjacent hole when the inner hole is heated. The effect improves the heating efficiency of the inner hole of the part.
If the magnetizer notch is mounted on the toroidal conductor or the reciprocating linear conductor, the current can be expelled from the lower flat surface of the conductor. This inductor is used for planar heating to enhance the proximity effect and improve the efficiency of planar heating.
