Magnetic Circuits and Transformers

Magnetic Circuits and Transformers - Magnetic Circuits and...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Magnetic Circuits and Transformers Sattar Hussain [email protected]
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
1- Magnetic Field It is customary to represent the magnetic field by means of lines of forces that can be traced as a closed loops exiting at magnetic north pole and entering at magnetic south pole. These line are called flux lines . The flux lines take the least resistance path; that is, they are easier to set up in an iron medium than in the air.
Image of page 2
The total number of flux lines is referred to as magnetic flux ϕ measured in weber (Wb) . The density of flux lines per unit of cross-sectional area perpendicular to the direction of the flux lines is called flux density, B , measured in Wb/m 2 or Tesla (T). The flux ϕ is then defined as the integral of the flux density over some surface area, A . If the flux is uniform over the cross sectional area A , then: = A BdA φ A B . = φ
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The magnetic resistance that tends to oppose the establishment of magnetic flux lines is referred to as reluctance, . Reluctance of iron bar is much less than air reluctance. Hence, the iron bar is an easier path than air for flux lines. 2- Magnetic Field Produced by Currents A conductor carrying an electric current I exhibits a magnetic field in the space surrounding it.
Image of page 4
The magnetic field is stronger near the conductor and decreases farther a way from it. The magnetic flux, ϕ , increases when the current , I increases. The direction of flux lines is determined by Ampere’s right- hand rule (RHR) . It states: when the thumb points to the current direction, the fingers point to the direction of magnetic field lines.
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon