# LCR meter working principle and its advantages and disadvantages

An LCR meter, short for Inductance (L), Capacitance (C), and Resistance (R) meter, is a specialized electronic instrument used to measure the inductance, capacitance, and resistance of electronic components such as capacitors, inductors, and resistors. These measurements are crucial in various fields of electronics, including circuit design, quality control, and troubleshooting. Let us understand its types before we explore LCR meter working principle and its advantages, disadvantages and applications.

## What is LCR meter and its types

As mentioned, In "LCR" the letters L, C and R stands for inductance, capacitance and resistance respectively. The device which measures these parameters is known as LCR meter.

Digital LCR meter type measures I(through DUT) and V (across DUT) and phase angle between measured I and V. From these measured parameters useful impedance parameters are calculated. LCR meter can also be used to measure impedance which is later converted to L, C or R for display.

There are two **LCR meter** viz. benchtop and handheld.
Benchtop are developed for bench applications and hence are kept at fixed location without much of
movement. Handheld are developed for portable applications and hence can be moved around for
test and measurement purpose.

Handheld LCR meters are lightweight and are battery powered.
It usually will have USB port to transfer data tothe PC/Laptop.
It provides measurement of inductance and AC resistance. It will usually have
measurement accuracy between 0.1% to 0.2%.

Benchtop LCR meter will have additional features compare to handheld type such as
programmable frequency setting. It will have very higher measuement accuracy of about 0.01%.
It provides advanced measurement capabilities such as DC bias current and voltage, sweep etc.
This type of LCR meter is used for AC calibration of L, C and R.
Typically measurements is performed at frequencies such as 100Hz, 120Hz, 1kHz and 10kHz.

Based on display formats LCR meter types are further categorized into analog and digital. Analog type are cheaper compare to digital type as they are made of basic discrete components. Digital type are costlier but are more accurate compare to analog counterpart.

## LCR meter working principle | How LCR meter works

Before we move to understand how LCR meter works, let us understand concept of impedance first. As shown in the figure, impedance consists of two parts viz. resistance (i.e. real) and reactance(i.e. imaginary). Zs represents series impedance which is combination of resistance(Rs) and reactance(Xs).

Impedance can be expressed with magnitude |Z| and phase angle θ
When θ>0 the reactance is inductive and
when θ<0 the reactance is capacitive.
There are two reactance types viz. inductive reactance (XL) and
capacitive reactance (XC). They can be expressed as follows:

XL = 2*π * f * L

XC = 1/ (2* π * f * C)

Impedance can be measured either in series or in parallel mode.
Impedance in parallel mode can be expressed as reciprocal of admittance(Y).

Here , Z=1/Y,

Y = G + j*B, where G = Conductance and B = Susceptance

There are various techniques for the measurement of impedance.
The most common method is nulling type bridge as shown in the figure-1 above.
When there is no current flow through detector(D), value of unknown impedance can be expressed as follows:

Zx = (Z1/Z2)*Z3

Different applications use different combinations of L, C and R as elements of the bridge. Hence LCR meter working principle depends on its application usage.

The working principle of LCR meter involves the application of an alternating current (AC) voltage or current signal to
the component under test and then measuring the response of the component to that signal. Here's a breakdown of the working principle.

➨Selection of Test Frequency: LCR meters allow users to select the frequency of the AC signal applied to the component.
The choice of frequency depends on the characteristics of the component being tested and the required measurement accuracy.
Lower frequencies are typically used for measuring inductance, while higher frequencies are used for capacitance measurements.

➨Measurement of Impedance (Z): The LCR meter applies an AC signal of the selected frequency to the component under test.
The impedance (Z) of the component consists of R, L and C. At the selected frequency,
the impedance is calculated using the relationship between voltage and current as explained above.
The impedance is a complex quantity, consisting of both magnitude and phase angle.

➨Separation of Components: Once the impedance is measured, the LCR meter separates the components L, C and R
from the impedance using various techniques such as phase-sensitive detection or bridge circuits.

➨Measurement of Resistance (R): The resistance component of the impedance is determined by measuring the phase angle between the applied
voltage and the current flowing through the component. This phase angle represents the resistive component of the impedance.

➨Measurement of Inductance (L) and Capacitance (C) : The inductive and capacitive components of the impedance are determined by
measuring the phase shift between the applied voltage and the current. By knowing the frequency of the applied signal,
the LCR meter can calculate the inductance and capacitance of the component.

➨Display of Results: The measured values of resistance, inductance and capacitance are typically displayed on the LCR meter's screen or
outputted to a computer for further analysis.

## Advantages and Disadvantages of LCR meter

Following are the **advantages of LCR meter**.

1. It measures passive components with minimal of errors. Hence LCR meters are highly accurate instruments, providing
precise measurements of L, C and R.

2. LCR meters typically offer a wide measurement range, allowing users to measure components with a broad range of values.

3. LCR meters can quickly measure the parameters of electronic components, saving time during testing and production processes.

4. Many modern LCR meters feature automatic measurement capabilities, which streamline the testing process and reduce the likelihood of errors caused by manual operation.

5. LCR meters can measure multiple parameters simultaneously, providing comprehensive insights into the characteristics of electronic components.

6. These instruments are very easy in calibration.

7. There are many companies which manufactures the LCR meter and hence more features and options are available for users.

Following are the **disadvantages of LCR meter**.

1. High quality LCR meters can be expensive.

2. Operating an LCR meter effectively requires a certain level of technical expertise.

3. Some LCR meters are bulky and not easily portable.

4. LCR meters are typically designed to operate within specific frequency ranges. While they can provide accurate measurements within these ranges, they may not be suitable for components that operate at very high frequencies.

5. LCR meters require regular calibration and maintenance to ensure accurate measurements over time.

## LCR meter manufacturers or vendors

Following are the best LCR meter manufacturers or vendors:

• Keysight technologies

• Meco Instruments P.Ltd (www.mecoinst.com)

• IET Labs, Inc. (www.ietlabs.com)

• Scientific Mes-Technik Pvt. Ltd. INDIA

• Extech Instruments

• InnovateUs Inc.

• Stanford Research Systems, Inc.

• Sigma Instruments

## LCR meter applications

LCR meters find applications in various industries and fields due to their ability to accurately measure the properties of
electronic components. Some common applications are as follows.

• Engineers use LCR meters to characterize passive electronic components such as capacitors, inductors, and resistors during the design and testing of electronic circuits.

• LCR meters are employed in manufacturing facilities to verify the quality and consistency of electronic components.

• LCR meters are utilized in material analysis applications to measure the dielectric properties of materials.

• LCR meters are employed to measure the inductance and quality factor (Q-factor) of transformers and inductors.

• LCR meters can analyze the frequency response of electronic components, providing insights into their behavior across different frequencies.

• In RF (Radio Frequency) and microwave applications, LCR meters are used to measure the impedance of components and circuits. This information helps engineers design impedance-matching networks to optimize power transfer and signal integrity.

• LCR meters are used to measure the impedance of batteries, providing insights into their internal resistance and capacitance.

• LCR meters are valuable tools in educational institutions and research laboratories for teaching basic principles of electronics and conducting experiments on passive components, circuits, and materials.

**Conclusion** : In summary, the LCR meter works by applying an AC signal to the component under test, measuring the impedance,
and then separating the impedance into its individual components of resistance, inductance, and capacitance using various techniques.
LCR meters remain essential tools for engineers, technicians, and researchers involved in electronics design, manufacturing, and testing.
The benefits they offer in terms of accuracy, versatility, and efficiency outweigh many of the drawbacks associated with their use.