A description of the measurement parameters of the magnetic element

1. Turns ratio TR: The ratio of primary and secondary windings to detect the turns ratio and coupling coefficient of transformer windings.

2. Phase PH: winding direction. Detect the winding direction of the primary and secondary transformers.

3. Inductance Lx: the proportional coefficient of the time change rate of voltage and current (e=L). Detect the magnetic permeability of the iron core

factor µ, mechanical size, completeness and absolute number of windings.

4. Inductance Lx overlap DC Bais: Detect the magnetic saturation characteristics of the iron core.

5. Leakage inductance LK: the equivalent inductance formed by the cutting of the leakage flux. Detect the permeability µ of the iron core and the winding

The coupling coefficient formed.

6. Quality factor Q: The ratio of the inductance (2πfL) of the inductor to the resistance (ACR).

7. Capacitance between coils Cp: stray static capacitance between coils. Detect the distance between coils, insulation materials and isolation design.

8. DC resistance DCR: copper wire resistance. Detect PIN solder joints, copper wire material, design line length, open and short circuit, etc.

9. AC resistance ACR: copper wire resistance plus the equivalent resistance caused by hysteresis loss and eddy current loss. Except for inspection

In addition to measuring copper wires, it also measures the magnetization and insulation of the iron core material.

10. Impedance Zx: the absolute impedance of the transformer.

11. Balance BL: Balance test between two sets of transformer windings. Detect inductance balance and resistance balance.

12. Pin short circuit PS: the short circuit between the non-conducting pins. Detect short circuits caused by enamel or solder between coils.

二 Magnetic component measurement technology description

1. Correct short-circuit reset SHORT: Irregular short-circuit reset will directly affect the low inductance and quality factor

The accuracy of the measurement of element, series equivalent resistance (ESR), etc.

2. Correct open circuit return to zero OPEN: Irregular open circuit return to zero will directly affect the high inductance and high frequency measurement

Accuracy. The intermediate ground isolation part is to consider removing the distributed capacitance between the wires.

3. Precautions for four-point measurement

When measuring at both ends, wiring impedance and contact impedance will appear in the measurement results, both of which will cause errors, especially contact impedance is the main factor causing instability. It directly affects the stability and accuracy of low inductance measurement, quality factor (Q), series equivalent resistance (ESR), impedance (Z), etc. The four-point measurement can deduct these effects.

4. Nonlinear inductance

The inductance of the inductance usually takes the inductance of the iron core in the linear region as the display value, but the definition of the linear region is not very clear, even in the linear region, the inductance is not strictly linear. In addition, the relationship between the test current Im and the test voltage Vm, the output impedance Zo of the instrument, and the impedance Zx of the inductor is as follows:

It can be seen from the above formula that the output impedance Zo of the test instrument is different, even if the set test voltage Vs is the same, the actual test voltage Vm on the object under test is also different.

5. Temperature change

Temperature changes must be taken into consideration especially when measuring inductances with high temperature coefficients. Anything that has just been scalded with a soldering iron or touched by hand will affect its sensitivity due to temperature changes. In addition, the results of measurements in different places (environments) must also consider the temperature difference of the surrounding environment.