Technical characteristics of ferromagnets

For magnetic circuits with variable ppm
When an inductive coil with an air gap is connected to an alternating sinusoidal voltage source, alternating current and current appear in the circuit.

Dependence B (H) - magnetization curve - the main characteristic of a ferromagnetic material; with alternating current it reverses according to hysteresis, due to the presence of residual magnetism Br and coercive (retarding) force Hc.

In a uniform magnetic field, the properties of a ferromagnetic material are described by the hysteresis dependence B (H)




In the case of an alternating magnetic field, the magnetic induction changes according to the hysteresis dependence



Bs - magnetic saturation induction
Br - residual magnetic induction (H = 0)
Hm - the amplitude of the magnetic field
Hc - coercive force (B = 0)

NS <4kA / m - material is magneto-soft
Нс> 4кА / м-material magneto-solid

Magneto-soft materials

With round hysteresis loop



With rectangular hysteresis loop



With linear dependence B (H)



Magnetic cores made of ferromagnets with a rectangular hysteresis are used in the RAM of digital electronic computers, automation devices, magnetic amplifiers.

Magnetic cores made of ferromagnets with a rounded hysteresis are used for the manufacture of electrical machines.

Magnetic cores made of ferromagnets with linear properties are used to manufacture inductive coils in radio engineering (antenna devices, transmitters, etc.)
The ferromagnetic core enhances the magnetic field induced by the winding and increases the emf of self-induction. To reduce ppm F and therefore the current I required to create F, the coils supply the magnetic core (core).