#12 - Capacitance and Inductance Measurement

🔍 Why is it so difficult to accurately measure a capacitor or an inductor?

 Measuring capacitance and inductance is tricky. You cannot measure them with a simple DC excitation — instead, a sinusoidal signal must be used, and the instrument evaluates phase shift. 

In practice, only LCR meters can do this properly.

🎯 The most important setting: frequency

For accurate measurement, you must choose the frequency where the given impedance is dominant:

➡️large capacitance → lower frequency

➡️small capacitance → higher frequency

This is necessary because the same component can give completely different values at different frequencies.

⚠️ But there is another major challenge: cable length

The standard 50 cm crocodile-clip measurement leads are literally unusable in production test systems.

In our setups, there is 1–3 meters of cable between the instrument and the probe fixture — and this completely alters the impedance.

Here’s how we improve measurement accuracy:

🔸 equal-length wires

🔸 twisted pairs for source–sense lines

🔸 low-frequency multiplexing

🔸 pre-validation with the final cable length

Without these measures, the results can be highly misleading, especially in production environments.

In ProDSP measurement systems, we integrate these solutions to achieve laboratory-grade LCR accuracy even on the production line.

Download CapacitanceAndInductance.pdf