Circuito magnético

Magnetic circuit

the circuit

The magnetic circuit is represented as a closed path formed by lines of magnetic force or magnetic flux. Such a magnetic circuit is associated with completely different magnetic quantities such as mmf, flow reluctance, permeability, etc.

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Imagine the simple magnetic circuit shown in the figure. This circle consists of an iron core with a cross-sectional area of ​​“a” in m2 and an average length of “l” in m. A coil with N turns is wound around one edge of the square core, which. is animated by a source. This source passes a current I through the coil. This current-carrying coil creates the flux (Ф) that completes its path through the core, as shown in the figure.

  • Magnetic effect of an electric current

This is analogous to an electrical circuit in which an IEMF source of E volts drives a current I that completes its path through a closed conductor with resistance R. This analog circuit is shown in the figure.

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Let us derive the relationship between MMF, flow and reluctance.

I = current flowing through the coil.

N = number of revolutions.

Ф = river in Webers.

B = flux density in the core.

µ = Absolute permeability of the magnetic material

μ R = Relative permeability of the magnetic material

The intensity of the magnetic field inside the coil is given by

H = (NI/l) AT/m

The flux density is now B = µH

B = ((µ Ó μ R NI)/ l) Wb/m 2

  • Magnetic field through straight conductor

Since the cross-sectional area is now “a” m2,

∴ The total flux in the core is

ф = Ba

ф = ((µ 0 μ R NI a)/l) Wb

that is, ф = (NI)/(l/ µ 0 μ R A)

ф = mmf / reluctance

ф = F/S

Where,

NI = F (mmf magnetomotive force in AT)

S = (l/µ 0 μ R a) (Resistance caused by the magnetic path).

This expression for flux is very similar to the expression for current in a circuit.

I = electromotive force / resistance

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