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 Î¼H 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 Î© to 200.0 MÎ©.

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 Î¼F or smaller. For capacitors that are 10 Î¼F 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 (XC) – Property by the virtue of which it can oppose the flow of current
6. Capacitive Reactance (XC) = 1 / (2Ï€ f C). Unit of XC Ohm (Î©)
7. Capacitance is measured in pico Farad, micro Farad, milli Farad (pF, ÂµF, 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 Ï‰ is defined as the ratio of the reactance of the capacitor to its series resistance. Q = (XC / 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/XC 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 (XL) – Property by the virtue of which it can oppose the flow of current
6. Inductive Reactance (XL) = (2Ï€ f L). Unit of XL Ohm (Î©)
7. Inductance is measured in micro Henry, milli Henry, Henry (ÂµH, mH, H)
8. Q-Factor – The Quality factor or the Q factor of an inductor at the operating frequency Ï‰ 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 = (XC / 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.

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