Study of Series R-L-C Circuit

 Aim:- Study of Series R-L-C Circuit to;

1.     Calculate the values of unknown parameters of R-L-C circuit.

2.     Determine the power factor of the circuit.

3.     To draw a phasor diagram of the circuit based on practical data and find out the applied voltage and power factor from the phasor diagram.

Apparatus Required:-

S. No.			Name of Equipment	Type	Range		Quantity
1.			Ammeter	MC	0-5A		1
3.			Voltmeter	MC	0-300V		3
4.			Inductive Coil	Variable	5A, 250V		1
5.			Rheostat	Single tube	500ohms, 5A		1
6.			Capacitor	-	-		1
7.		Single Phase variac		-	230V, 10A	1

Theory:- In the present circuit, resistance R, inductor L and copulation C are connected in series across a voltage Source V. Thus the current in all the elements is same, whereas voltage across each element would be different. The resultant applied voltage V is the phasor sum of all the voltages across these elements. In such a series circuit, following basic relations can be derived:

                               Voltage across the resistance, V_R = IR

                              Voltage across the inductance, V_L = IX_L

                              Voltage across the capacitance, V_C = IXc

                              Power drawn by the circuit, P =VI

                              Power factor of the circuit, = P/VI

Where,

                             X_L = Inductive reactance  =   =  2  

                             X_C Capacitive reactance =  =

The power factor of such a circuit is lagging the power Factor of this dreat will be leading Hence, by measuring the voltage across various elements, applied voltage: current flowing in the circuit and the power consumed by the circuit, all the parameters of the circuit can bị calkulated.

 

Circuit Diagram:-       

PROCEDURE:

1.     Connect the circuit as per the circuit diagram shown in fig.

2.     Adjust the setting of variac, so that applied voltage to the R-L-C series circuit is zero.

3.     Switch-ON the main supply.

4.     Apply a low voltage to R-L-C series circuit and record the readings of ammeter, wattmeter and voltage across resistor, inductor, capacitor and across the terminals C and E of the variac. Voltages should be measured by a single voltmeter to increase the accuracy of measurement.

5.     Repeat step 4 for increased voltage applied to the circuit. It is sufficient to record 3 or 4 set of readings.

6.     Switch-off the main supply.

7.     Draw the phasor diagram, corresponding to one set of reading, preferable at higher voltage, and verify the calculated value of power factor.

 

 

Observation Table:-

S. No.	V (V)	I(mA)	VR(V)	VL(V)	VC(V)
1.	230.5	0.4	51.7	103.3	320.2

 

Calculation:-

S. No.	R=	XL=	XC =	Z =	P.F. =
1.	129.25	258.25	800.5	576.25	0.231

 

Precaucation:-

1.     Make the connections properly.

2.     Note the readings of voltmeters and ammeters properly.

3.     Remove insulations from the connecting wire so as the current will flow properly