Use of LCR-Q meter to measure the value of a given Capacitor and Inductor

Experiment No. : 2

Experiment Name :

Use of LCR-Q meter to measure the value of a given capacitor and inductor.

Objective :

To use LCR-Q meter to measure the value of a given capacitor and inductor.

Theory :

LCR-Q meter : LCR-Q meter is a measuring instrument which is used to measure the value of inductance (L), capacitance (C), resistance (R) and the Q-factor or quality factor of inductor and D-factor or dissipation factor of capacitor. It can measure inductance in the range of 200.00 μH to 2000.0 H, capacitance in the range of 2000.0 pF to 2.000 mF and the resistance in the range of 20.000 Ω to 200.0 MΩ.

When measuring capacitance selecting, the right frequency is important in obtaining the most accurate measurement results. Generally, 1 kHz test frequency is used to measures capacitance of 0.01 μF or smaller. For capacitors that are 10 μF or larger, a lower frequency of 120 Hz is used.

Typically, a 1 kHz test frequency is used to measure inductors that are used audio and RF circuits. And a 120 Hz test frequency is used to measures inductors that are used for filter chokes in power supply.

Some Properties of Capacitor : These are some basic properties of a capacitor.

1. It is a passive element
2. It can store electrostatic energy
3. It can oppose the change in voltage
4. It can pass AC and block DC
5. Capacitive Reactance (X_C) – Property by the virtue of which it can oppose the flow of current
6. Capacitive Reactance (X_C) = 1 / (2π f C). Unit of X_C Ohm (Ω)
7. Capacitance is measured in pico Farad, micro Farad, milli Farad (pF, µF, mF )
8. Q-Factor – A capacitor with small series resistance R associated within. The Q-factor or the quality factor of a capacitor at the operating frequency ω is defined as the ratio of the reactance of the capacitor to its series resistance. Q = (X_C / R). It is a dimensionless quantity.
9. D-Factor – The dissipation factor of a capacitor is the power loss when AC is applied through the capacitor. This power is either absorbed by the dielectric material or internal/external resistance. Externally, the leads, pads, and solder all lead to an increase in resistance. D = R/X_C or D = 1/Q

Some Properties of Inductor : These are some basic properties of an Inductor.

1. It is a passive element
2. It can store electromagnetic energy
3. It can oppose the change in current
4. It can pass AC and block DC
5. Inductive Reactance (X_L) – Property by the virtue of which it can oppose the flow of current
6. Inductive Reactance (X_L) = (2π f L). Unit of X_L Ohm (Ω)
7. Inductance is measured in micro Henry, milli Henry, Henry (µH, mH, H)
8. Q-Factor – The Quality factor or the Q factor of an inductor at the operating frequency ω is the ratio of reactance of the coil to its resistance. Every inductor possesses a small resistance in addition to its inductance. The lower the value of this resistance R, the better the quality of the coil.
9. Q = (X_C / R). It is a dimensionless quantity.

Circuit Diagram :

Observation Table :

Apparatus used:

1. We should discharge the capacitor before measuring the capacitance.
2. To get accurate result we should calibrate the LCR-Q meter before measurment.