Three phase power measurement using two wattmeter method

AIM:

To measure the power in 3 -phase balanced star connected load and to determine the power factor.

APPARATUS REQUIRED:

• Wattmeter  2.50 A, 600V 2 No’s
• Ammeter 0 – 2.5 A M/I Type 1 No’s
• Voltmeter 0 – 500 V M/I type 1No’s 
• Lamp load 
• Connecting wires.

THEORY:

The following methods are used for the measurement of three phase power.

1. One Wattmeter Method : For balanced Load
2. Two Wattmeter Method : For balanced Load / Unbalance Load
3. Three Wattmeter Method  : For balanced Load / Unbalance Load

PROCEDURE:

• Connect the circuit as shown in the Figure to measure the power in star connected load. 
• Check the circuit and switch on 3Φ supply switch. 
• Take the readings of the ammeters, voltmeters and wattmeter’s connected in the circuit.
• Total power measured is given by (w1 + w2) watts. 
• Calculate the power by formula P = √3VLILcosΦ 
• Compare the two results. 
• Repeat the experiment for different loads

CIRCUIT DIAGRAM :

OBSERVATION TABLE:

FORMULA USED:

• Real power,P = w1 + w2 
• Reactive power,Q = √3 (w1 – w2 )
• Tan Φ = √3 (w1 – w2 )/ (w1 + w2)
• Power factor = cosΦ

RESULT:

Thus the power in 3 -phase balanced star connected load is measured  and determined the power factor