LCR meter

The phase angle between the voltage and current is also measured in more advanced instruments; in combination with the impedance, the equivalent capacitance or inductance, and resistance, of the DUT can be calculated and displayed.

(However, care must be taken, as some LCR meters will be damaged by the generated EMF produced by turning the rotor of a permanent-magnet motor; in particular those intended for electronic component measurements.)

Benchtop LCR meters sometimes have selectable test frequencies of more than 100 kHz, with the high end Keysight E4982A operating up to 3 GHz.

In addition benchtop meters typically allow the usage of special fixtures (i.e., Kelvin wiring, that is to say, 4-wire connections) to measure SMD components, air-core coils or transformers.

They involve adjusting variable calibrated elements until the signal at a detector becomes null, rather than measuring impedance and phase angle.

Early commercial LCR bridges used a variety of techniques involving the matching or "nulling" of two signals derived from a single source.