Measuring Inductance with Multimeter Capacitance Range
According to circuit principles, the capacitance reactance of a capacitor and the inductance reactance of an inductor are XL=2 π f L. If the conversion task of capacitance impedance voltage (C-XC-V) is reasonably utilized, the inductance can be measured using the capacitance range of a digital multimeter. If the reactance of the tested inductor is equal to the capacitance reactance XC of the corresponding capacitor, i.e. XL=XC, then at the same time, the voltage on the tested inductor and the corresponding capacitor is equal. The capacitance capacitance reactance voltage (C-XC-V) converter is used to complete the conversion of inductance reactance voltage (L-XL-V). Without changing any circuit, directly connect the measured inductance L to the capacitor input socket XC of the digital multimeter capacitor range for inductance measurement. Although the screen of a digital multimeter displays the capacitance value, it is the capacitance value corresponding to the capacitance reactance that is equal to the measured inductance reactance. To truly complete the measurement of inductance, it is necessary to convert the displayed capacitance value into the actual measured inductance value.
2. Convert the displayed value of the inductance to the measured inductance value. The measurement of the capacitance range of a digital multimeter relies on the AC measurement signal inside the meter. Measure the measurement signal of the capacitance range of various models of digital multimeters, whether it is a 3-and-a-half digital multimeter or a 4-and-a-half digital multimeter. As long as the maximum limit of the capacitance range is 20 μ F, the measurement signal is frequency f=400Hz and voltage U=30mV (except for digital multimeters with large capacitance measurement function, such as UT70B, which has a maximum limit of 40000 μ F for the capacitance range and uses ultra-low frequency signals for measurement). Substitute f=400Hz into the formula:
The conversion formula between the displayed value C and the measured inductance value L in the capacitance range of a digital multimeter can be obtained
The unit of capacitance C is μ F, and the unit of inductance L is H. The measurement range of inductance is from 8mH to 20H.
