Practical case: Measure inductance with an LCR meter

Materials

• 1 LCR meter (with clip leads; 2-wire mode is fine)
• 1 Inductor under test, L1 (e.g., 100 µH radial inductor)
• 2 Short hookup wires or clip adapters (if needed)
• 1 Small breadboard or terminal block (optional, for stable contact)
• 1 Anti-static mat or non-conductive surface (recommended)

Wiring guide

• HI and LO abbreviations:
• HI = the “high” test terminal/clip of the LCR meter.
• LO = the “low” test terminal/clip of the LCR meter.
• Prepare the LCR meter:
• Select L mode (inductance). Set test level per datasheet (commonly 0.1–1 Vrms) and start with 1 kHz test frequency.
• Perform open/short calibration per your meter: “open” the leads (not touching), then short them together, store corrections.
• Connect the device under test (DUT):
• Clip the HI lead to the node marked ●HI and the LO lead to ●LO on the schematic.
• Keep lead length short; avoid touching the junctions to reduce stray capacitance and resistance.
• Orientation:
• The inductor is non-polarized; either lead can be HI or LO.

Schematic

                                +V
                                │
                                ● V
                                │─────────────────────────────┬────────────────────┐
                                                              │                    │
                                                          ┌───┴───┐            ┌───┴───┐
                                                          │       │            │       │
                                                          │       │            │       │
                                                          │       │            │       │
                                                          └───┬───┘            └───┬───┘
                                                              │                    │
                                                              │                    ● I
                                                              │                    │
                                ──────────────────────────────┴────────────────────┴──
                                                                                     │
                                                                                    GND

                 LCR1  Medidor LCR (1 kHz, 1 Vrms)                L1  Inductor 10 mH

Measurements and tests

• Calibration:

  • Perform “open” calibration: separate HI and LO clips in air; run OPEN cal.
  • Perform “short” calibration: connect HI to LO; run SHORT cal.
  • Return to normal mode; do not change lead geometry afterward.

• Inductance at 1 kHz:

  • Connect L1 across ●HI–●LO.
  • Set Mode = L (or L-Q), Frequency = 1 kHz, Test level = default (e.g., 1 Vrms).
  • Read L (inductance). Compare to nominal (e.g., 100 µH ± tolerance).

• Frequency dependence:

  • Repeat L measurement at 120 Hz, 1 kHz, and 10 kHz.
  • Expect L to vary slightly; at higher frequencies, proximity/skin effects and approaching self-resonance can shift readings.

• Q factor and dissipation (optional):

  • If available, read Q (quality factor) or D (dissipation factor) at 1 kHz.
  • Higher Q indicates lower losses; note that Q generally rises with frequency until near self-resonance.

• DCR (DC resistance) check:

  • If your LCR meter provides DCR (Rdc) mode, select it and measure with L1 still on ●HI–●LO.
  • Typical DCR for small 100 µH inductors might be tens to a few hundred milliohms; verify against the datasheet.

• Stability check:

  • Lightly press or move the leads and observe L; large changes indicate poor contacts or excessive stray effects—re-seat the clips closer to the body.

Common mistakes and tips

• Not calibrating the meter: Always do open/short cal with the same lead arrangement you’ll use for measurement.
• Long flying leads: They add series resistance and parasitic capacitance; keep connections short and consistent.
• Touching the DUT or leads during measurement: Body capacitance perturbs the reading.
• Ignoring frequency: Always report test frequency with the measured L value.
• Misreading units: Confirm µH vs mH; many meters let you select auto/manual ranges.

Safety notes

• Do not connect any external power source during LCR measurements; the meter provides its own small AC stimulus.
• Avoid measuring inductors that are part of a live circuit; remove and measure them isolated or ensure the circuit is fully unpowered and discharged.

Going further

• Try 4-wire Kelvin fixtures (if your meter supports them) for low-DCR inductors to reduce lead resistance errors.
• Sweep frequency to estimate self-resonant frequency (SRF): the apparent L collapses and measured C dominates near SRF.

Validation: The schematic identifies L1 per the materials, uses +V at the top and GND at the bottom, shows closed connections with no loose ends, and includes black-dot measurement points labeled with abbreviations (HI, LO) explained in the guide.

More Practical Cases on Prometeo.blog

Carlos Núñez Zorrilla

Electronics & Computer Engineer

Telecommunications Electronics Engineer and Computer Engineer (official degrees in Spain).

Follow me:

Who we are