LCR Meters

LCR Meters, also known as LCR bridges or LCR inductance meters, are electronic test equipment used to measure the inductance (L), capacitance (C) and resistance (R) of an electronic component.

When there is a change in the current flowing through a conductor, a corresponding change is induced in the voltage in it and in conductors surrounding it. This property is known as inductance. The ability of a body or a conductor to store electrical charge is known as capacitance. The opposition that a conductor offers to passing electric current through it is called resistance.

Most LCR meters use AC signals to measure the impedance of components. When using an LCR meter make sure you are using the correct settings as the wrong settings can cause poor measurement accuracy. Both analogue and digital LCR meters are available. The analogue is less expensive, and the digital variety is seen to be more accurate.

What Are the Uses of an LCR Meter?

A digital LCR meter is used to measure the impedance flowing through a Device Under Test (DUT). It measures the voltage (V) across it, the current (I) flowing through it, and the phase angle between current and voltage. Subsequently, you can determine all the impedance parameters from these three factors.

Thus, an LCR meter measures the following parameters related to a circuit:

• Inductance
• Capacitance
• Resistance
• Dissipation factor
• Quality factor
• Current
• Voltage
• Phase angle between the current and voltage
• Conductance

What are the types of LCR Meters?

Handheld LCR meters: Small, lightweight and portable. They have multiple test frequencies and the data it captures can be transferred to a PC via a USB port. These LCR testers are typically digital, and used in field operations.

Benchtop LCR meters: Big and bulky. They can be operated on programmable frequencies and can be controlled via a computer. Benchtop LCR meters are able to measure higher maximum test frequencies, enabling a wider range of measurements. They also typically feature Kelvin connections (also known as four-terminal sensing) to minimise measurement errors caused by lead and contact resistances.

Techniques used with LCR Meters

Bridge Method: This method is used for measuring frequencies below 100 kHz.

LCR Measurement by Current-Voltage Technique: Using this method, the LCR measurement of a component is done by measuring the current and voltage. Then the impedance values are found out from these two quantities.

LCR Meter vs Multimeter

While both LCR meters and multimeters are essential tools for electronic testing, they serve distinct purposes and offer varying levels of precision. Understanding their differences is crucial for selecting the right instrument for specific applications.

LCR Meters

Primarily designed to measure inductance (L), capacitance (C), and resistance (R) with high accuracy. Utilises AC signals to determine impedance and provide detailed analysis of the components within an electrical current.

Use cases include:

• Component characterisation: Determining precise values for capacitors, inductors, and resistors in circuit design.
• Quality control: Verifying component tolerances in manufacturing processes.
• Material testing: Measuring impedance of materials for research and development.

Multimeters

Measures voltage (V), current (A), and resistance (R). Primarily used for troubleshooting, circuit testing, and general electrical measurements. Often include basic capacitance measurement capabilities, but lack the precision and frequency range of dedicated LCR meters.

Use cases include:

• Troubleshooting: Identifying faults in electrical circuits and electronic devices.
• Circuit testing: Verifying voltage levels and continuity in assembled circuits.
• General electrical measurements: Measuring voltage in power supplies, current in wiring, and resistance in resistors.

Can LCR Meters Measure ESR (Equivalent Series Resistance)?

Yes, LCR meters are capable of measuring Equivalent Series Resistance (ESR), a vital parameter for capacitor analysis. ESR is the total resistance within a capacitor, accounting for factors like dielectric losses and lead resistance.

How LCR Meters Measure ESR:

• Impedance Analysis: LCR meters calculate ESR by measuring the capacitor's impedance at a specific frequency.
• Component Isolation: The meter analyses the complex impedance, then isolates the resistive component.

While LCR meters can handle ESR, dedicated ESR meters might offer better accuracy and speed in some cases.

Limitations and Considerations of LCR Meters in ESR Measurement:

• Low-Frequency Accuracy: Accuracy can be a concern at low frequencies, as the ESR component becomes relatively small.
• Component and Settings: Different types of capacitors (e.g., electrolytic, ceramic, tantalum) have inherent differences in their ESR characteristics. These factors need to be understood to correctly interpret results.

Best Practices for ESR Measurement Using LCR Meters:

• Parameter Selection: Choose the correct test frequency and voltage to match the capacitor's specifications.
• Meter Understanding: Learn how your specific LCR inductance meter calculates ESR, as methodologies can vary between models.
• Connection Techniques: Use Kelvin connections and short leads to minimise errors from lead and contact resistance.
• Component Mounting: Use appropriate fixtures for surface-mount components, avoiding stress during measurement.
• Temperature Control: Maintain a stable temperature, as ESR can vary with temperature, especially for electrolytic capacitors.
• Shielding: Protect the component and leads from electromagnetic interference, particularly at high frequencies.
• Measurement Averaging: Use the meter's averaging function to reduce noise and improve reading stability.
• Documentation: Record all test parameters and ESR readings for accurate comparison and analysis.

Common Mistakes When Purchasing LCR Meters

When selecting an LCR tester, avoid these common pitfalls:

• Frequency Range Limitations: If you're working with high-frequency components, don't purchase models with low frequency ranges.
• Accuracy vs. Budget: Don't sacrifice accuracy for a lower price, low-cost LCR inductance meters may not provide reliable readings for precision work.
• Connectivity Options: Ensure the LCR meter has the necessary connectivity (e.g., USB, PC interface) for data transfer, if required for your application.

Industrial Applications of LCR Meters

LCR meters play a crucial role across various industries, providing essential measurements for quality control, research, and development. Here are a few examples:

• Electronics Manufacturing: Inductance meters verify surface-mount component values on PCBs, ensuring capacitors and inductors meet tolerances.
• Automotive Industry: They test automotive electronic systems, like ECUs, and characterize wiring harnesses for reliable electrical connections.
• Aerospace and Defense: An LCR bridge is used to verify high-reliability components for avionics and military systems, meeting stringent specifications.
• Telecommunications: They test components in telecommunication equipment, like filters and transmission lines, ensuring required impedance.
• Medical Devices: LCR testers verify sensors and electronic components in medical devices, meeting strict regulatory requirements.

Your Trusted LCR Meter Supplier & Manufacturer

RS is a trusted supplier and distributor of high-quality LCR meters in Australia, catering to diverse measurement needs. We offer a comprehensive range of benchtop and handheld LCR meters, alongside complementary electronic component testers like Ohmmeters or ESD testers for all your electrical needs. Our catalogue features leading brands like Keysight Technologies, Peak Electronic Design, Aim-TTI, and many more.

For more information on delivery across Australia, please visit our delivery page.