List one advantage and one disadvantage of one wattmeter method.

List one advantage and one disadvantage of one wattmeter method. 
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1 Answer

Answer :

Advantages: 

1) Only one wattmeter is used. 

2) Less number of connections. 

3) Cost required is less. 

Disadvantages: 

1) Used only for 3- Φ balanced load and not for unbalanced loads. 

2) Star point must be accessible for connecting the Pressure coil. 

3) Delta connection must be opened to connect current coil. 

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