THEVENIN'S , NORTON'S AND MAXIMUM POWER TRANSFER THEOREM - ECS LAB (II year II Sem)

THEVENIN’S THEOREM

AIM:  To verify Thevenin’s theorem

APPARATUS REQUIRED:

                                                                                                                    

Sl.  No.	Name of the component	Specifications	Quantity
1	Resistors	1 KW	2
		2.2 KW	1
3	Regulated Power Supply (RPS)	0-30 V	1
4	Voltmeter	0-20V	1
5	Ammeter	0-20 mA	1
6	Decade Resistance Box (DRB)	10W-1MW	1
7	Bread Board		1
8	Multi meter		1

THEORY:

Thevenin’s Theorem:

    

The current flowing through a load resistance R_L connected across any two terminals A and B of a linear, active bilateral network is given by V­_oc /(R_th+R_L) where V_OC is the open circuit voltage also known as Thevenin’s voltage(V­_th) and R_th is the internal resistance known as Thevenin’s resistance of the network as viewed back into the open circuited network from terminals A and B with all voltage source replaced by their internal resistance (if any) and current sources by infinite resistance.

PROCEDURE:

Thevenin’s Theorem:

1. Apply a D.C. voltage from voltage source to the input terminals of the network and measure the output voltage V_oc with out load.

2. Connect the load at the output of the network and measure the current through the load

3. Disconnect the voltage source and load, short the input terminals of the network and measure the Thevenin’s equivalent resistance at the output terminals.

4. Adjust the input voltage of the voltage source that is equal to Thevenin voltage and apply to input terminals of the equivalent circuit.

5. Measure the load current I_Land compare it theoretical value and tabulate

PREACAUTIONS: 

      1. Connect the circuit elements as per the circuit diagram

2. Avoid loose connections of the circuit elements

3. Take the readings carefully and accurately

4. Do not tamper the circuit elements.

OBSERVATIONS:

Thevenin’s Theorem:

Sl. No	Input Voltage  V (volts)	Vth (volts) Theoretical	Vth (volts) Practical	IL (mA) Theoretical	IL (mA) Practical
1 2 3 4 5	5   10   15   20   25

For R_th

Sl No.	Rth Theoretical	Rth practically
1.

RESULT:

NORTON’S THEOREM

AIM:  To verify Thevenin’s and Norton’s theorems

APPARATUS REQUIRED:

                                                                                                                    

Sl.  No.	Name of the component	Specifications	Quantity
1	Resistors	1 KW	2
		2.2 KW	1
3	Regulated Power Supply (RPS)	0-30 V	1
4	Voltmeter	0-20V	1
5	Ammeter	0-20 mA	1
6	Decade Resistance Box (DRB)	10W-1MW	1
7	Bread Board		1
8	Multi meter		1

THEORY:

Norton’s Theorem:

    Any two terminal active network containing voltage sources and resistances when viewed from its out put terminals, is equivalent to a constant current source and a parallel resistance. The constant current is equal to the current which would flow in a short circuit placed across the terminals and parallel resistance is the resistance of network when viewed from these open circuit terminals after all voltage and current sources have been removed and replaced by their internal resistance.

PROCEDURE:

Norton’s Theorem:

1.      Apply DC voltage of 10V from voltage source to the input terminal of the network and measure the load current at the output of the network

2.      Apply D.C.voltage of 10V   and measure short circuit current I_sc by short-circuiting load terminals.

3.      Find Z_th by disconnecting the voltage sources and load, short the input terminals of the network and measure the Thevenin’s equivalent impedance at the output terminals.

4. Draw Norton’s equivalent circuits by connecting Z_th in parallel with I_sc.
5. Convert Norton’s equivalent circuit to Thevenin’s equivalent circuit and measure the load current I_L^l with connecting load at output terminals and compare with I_L
6. Norton’s theorem states I_L = I_L¹

PREACAUTIONS: 

      1. Connect the circuit elements as per the circuit diagram

2. Avoid loose connections of the circuit elements

3. Take the readings carefully and accurately

4. Do not tamper the circuit elements.

OBSERVATIONS:

Norton’s Theorem

Sl. No	Input Voltage  V (volts)	IN (mA) Theoretical	IN (mA) Practical	IL (mA) Theoretical	IL (mA) Practical	IL1 (mA
1 2 3 4 5	5   10   15   20   25

For R_th

Sl No.	Rth Theoretical	Rth practically
1.

RESULT:

MAXIMUM POWER TRANSFER THEOREM

AIM:  To verify maximum power transfer theorem.

APPARATUS REQUIRED:

Sl. No.	Name of the Component	Specifications	Quantity
1	Resistors	1KW	2
		2.2 KW	1
2	Decade Resistance Box (DRB)	10W-1MW	1
3	. Regulated Power Supply (RPS)	0-30 V	1
4	Ammeter	0-50 mA	1
5	Bread Board		1
6	Multimeter		1

THEORY: 

It states that in a D.C network maximum power is transfer from source to the load when the load resistance is equal to the source resistance. The source resistance is the internal resistance of the network as viewed from the load terminals.

In case of an AC network maximum power is transfer from source to the load when the load impedance is complex conjugate of the source impedance.

The maximum power transferred when R_s =R_L is P_max = V²_th / R_L.

PROCEDURE:   

1. Connect the circuit as shown in figure 3 (a).

2. Varying the load resistance in steps and note the ammeter readings and calculate power

3. Plot the graph by taking resistance on X – axis and power on Y – axis

4. R_s should be equal to R_L for maximum power transfer.

PREACAUTIONS: 

      1. Connect the circuit elements as per the circuit diagram

2. Avoid loose connections of the circuit elements

3. Take the readings carefully and accurately

      4. Do not tamper the circuit elements.

OBSERVATIONS:

Sl. No	Input Voltage  V (volts)	RL(W) Load Resistance	IL (mA ) Load Current	P = I2 RL Load Power
1 2 3 4 5 6 7 8 9 10	10     10   10     10   10   10   10   10   10   10	100 300 600 900 1200 1600 2000 2500 3000 3500

For R_th or Rs

Sl No.	Rth or Rs Theoretical	Rth or Rs Practically
1.

RESULT: