Keysight Technologies 16454A, Руководство по эксплуатации и обслуживанию

Страница: 28 / 41

Figure 3-2. Relationship among Current, Magnetic Flux, and Magnetic Flux Density
Generally , the magnetic ux density (B) induced by the current owing in an innitely long
straight wire shown in (a) of Figure 3-2 is expressed as Equation 3-2.
Equation 3-2. Magnetic Flux Density Induced by Current Flowing in an Innitely Long
Straight Wire
B =
I
2 r
On the other hand, the magnetic ux (8) induced by current owing in the closed loop shown
in (b) of Figure 3-2 is expressed as Equation 3-3. Note that L indicates the self-inductance of
the closed loop .
Equation 3-3. Magnetic Flux Induced by Current in Closed Loop
8 = LI
Furthermore , this magnetic ux (8) also can be expressed by integrating the magnetic ux
density (B) throughout the enclosed surface , as shown in Figure 3-2 (See Equation 3-4).
Equation 3-4. Relationship between Magnetic Flux and Magnetic Flux Density
8 =
Z
B ds
When a DUT (toroidal core) is mounted in 16454A, an ideal (no magnetic ux leakage) one turn
inductor is formed, as shown in Figure 3-3.
Figure 3-3. Measurement Principle When Using 16454A T est Fixture
3-2 Theory on Material Measurement