Measure Three Phase Power

 Aim:- To measure three phase power and power factor in three phase circuit by single-phase wattmeter under;

1.     Calculate the three phase power for balance load condition

2.     Calculate the three phase power for unbalanced load condition.

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Apparatus Required:-

S. No.	Name of Equipment	Type	Range	Quantity
1.	Wattmeter	Dynamometer	5A, 600V	1
2.	Voltmeter	MI	0 – 500V	1
3.	Ammeter	MI	0 – 5A	1
4.	Three Phase Load  arrangment	-	-	1
5.	Lamp load	Resistive	250V, 1KW	1

 

Theory:- Power consumed by three plisse balanced or unbalanced load connected in star or delta can be measured by using twa perly connected in the cicuit. The current coil of the wattmeter's are connected in series with the load in any iwo likes whereas the two pressure coils are connected between these lines and the third line as shown in below figure.

 

Circuit Diagram:-       

 

PROCEDURE:

1.     Make the connections as per the circuit diagram.

2.     Switch ON A C supply.

3.     For balanced load condition measured the values of wattmeters, ammeters

4.      Repeat the same process for unbalance load condition.

5.     Switch OFF all the loads and supply.

 

Observation Table:-

S. No.	Condition	IR	IY	IB	VR	VY	VB	M.F.	W1	W2
1.	Balanced  Load	1.6	1.6	1.6	235	235	285	2	280	280
2.	Unbalanced Load	1.7	2.6	2.7	280	245	185	2	290	520

 

Calculation:-

                                    Load Count of Voltmeter = 10V

                                    Load Count of Ammeter = 0.1A

                                    M.F. =

For unbalanced load condition,

                                    P.M. = W₁+W₂ = 1620 W

                                    P.C. = V_AI_A + V_BI_B+ V_CI_C = 1612.5 W

                                   % Error = 6.46 %

For balanced load condition,

                                     P.M. = W₁+W₂ = 1120 W

                                     P.C. = V_AI_A + V_BI_B+ V_CI_C = 1128 W

                                     % Error = 0.7 %

Precautions:

1.     All the connections should be tight and clean.

2.     The readings in ammeters should not exceed the current ratings of wattmeters.

3.     With negative deflection in wattmeter the connection should be reversed.