Basic Electrical Theory
MAGNETIC CIRCUITS
MAGNETIC CIRCUITS
What is a magnetic circuit? To better understand magnetic circuits, a basic
understanding of the physical qualities of magnetic circuits will be necessary.
EO 1.8
EXPLAIN the physical qualities of a simple magnetic circuit,
including relationships of qualities and units of measurements.
EO 1.9
Given the physical qualities of a simple magnetic circuit,
CALCULATE the unknown values.
EO 1.10
DESCRIBE the shape and components of a BH magnetization
curve.
EO 1.11
EXPLAIN the cause of hysteresis losses.
EO 1.12
Given Faraday’s Law of induced voltage:
a.
DESCRIBE how varying parameters affect induced voltage.
b.
CALCULATE voltage induced in a conductor moving through
a magnetic field.
EO 1.13
STATE Lenz’s Law of induction.
Magnetic Circuits
A magnetic circuit can be compared with an electric current in which EMF, or voltage, produces
a current flow. The ampere-turns (NI), or the magnetomotive force (Fm or mmf), will produce
a magnetic flux F (Figure 26). The mmf can be compared with EMF, and the flux (F) can be
compared to current. Equation (1-16) is the mathematical representation of magnetomotive force
derived using Ohm’s Law,
.
I
E
R
F =
(1-16)
Fm
R
mmf
R
where
F
=
magnetic flux, Wb
Fm
=
magnetomotive force (mmf), At
R
=
reluctance,
At
Wb
Rev. 0
Page 37
ES-01
