Exprement Maximum Power Transfer Theorem

Exprement

    Maximum Power Transfer Theorem

F    Unit Objective

At the completion of this unit, you will be able to verify maximum power transfer theorem.

F     Procedure

Maximum power transfer theorem states that in a linear, bilateral network, maximum power transfer takes place to the load only when load impedance matches or equals with the equivalent internal impedance (Thevenin’s impedance, R_TH) of the network.

 

A) Maximum Power Transfer Theorem for DC input voltage: 

20mA range

   Fig. P2.9.1 DC input voltage maximum Power Transfer Theorem

 

 

 

 

 

 

 

 

 

 

 

 

 

Step-1: Make connections as per above wiring sequence given & check the complete wiring as per the circuit arrangement.

Step-2: First keep the variable POT (P1) at fully CCW position & switch ON the power supply and adjust voltage to +12V.

Step-3: Now take the readings of Voltmeter & Ammeter at this POT position (i.e. at 0 ohm) & fill the corresponding table.

Step-4: Switch OFF the supply and remove from the network & also remove the network connection from load (RL) i.e. remove connections of power supply, AM(-) - 70.

    Now connect ohmmeter (Lab DMM) at 71 & 73 and set load (RL) to next reading by slightly varying the POT; set RL= 500W.

Step-5: Now remove the ohmmeter & make connection again as per wiring sequence and measure voltmeter & ammeter readings.

Step-6: Again remove supply & connect ohmmeter and set POT value as per table and follow above procedure to measure corresponding readings. Follow same procedure for each R_L value.

Table P2.9.1 DC input based Observation Table

RL (Ohms)	Measured Current (I)   (in mA)	Measured Voltage (V) (in volts)	O/P power (in mW)
			P=I2RL	P=V2/ RL
0 W
500 W
1K
1.5K
2K
3K
4K
6K
8K
10K

 

NOTE: Each time set ‘R_L’ (i.e. Load resistance) using ohmmeter as per table by disconnecting R_L from the network, otherwise loading occurs.

 The internal impedance (Thevenin’s impedance, R_TH) of the above network is equal to 1.5K, calculate R_TH by shorting 51 & 62 and connect ohmmeter at 55 & 63.

i.e. R_TH = (Ra // Rc ) + (Rb) = (1K // 1K) + (1K) = 1.5K.

 

 

 

 

B) Maximum Power Transfer Theorem for AC input voltage: 

   Fig. P2.9.2 AC input voltage maximum Power Transfer Theorem

 

 

 

 

 

 

 

 

 

 

 

 

 

Step-1: Make connections as per above wiring sequence given & check the complete wiring as per the circuit arrangement.

Step-2: Follow the same procedure as of DC measurement & fill the below corresponding table as per POT (load) value.

Table P2.9.2 AC input based Observation Table

 

RL (Ohms)	Measured Voltage (V) (in Vpp)	O/P power (in mW) P=V2/ RL
0
500
1K
1.5K
2K
3K
4K
6K
8K
10K

 

NOTE: 1) Each time set ‘R_L’ (i.e. Load resistance) using ohmmeter as per table by disconnecting R_L from the network, otherwise loading occurs.

2) In AC measurement using CRO/DSO, observe the peak-to-peak value & fill the corresponding table.

F     Conclusion

      As the theorem stated for the maximum transferred power to the load, when load impedance matches with the network internal impedance (Thevenin’s impedance, R_TH). Hence from the observed readings; at 1.5K load impedance you got maximum power, because internal network impedance is of 1.5K. Hence maximum power transfer theorem is verified. This is followed to be true for DC 12V as well as AC 12V_RMS voltages.

 

F     Equipments required

1.      DC power Supply 0 – 15V (set to 12V).

2.      DMM.

3.      CRO/DSO.

4.      CT Master Unit (for 12V_RMS AC supply).

5.      Panel No. P2.

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