Define power factor. State its significance. What is the condition for unity power factor ?

Define power factor. State its significance. What is the condition for unity power factor ? 
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1 Answer

Answer :

Definition of Power factor: Power factor is cosine of angle between voltage and current. 

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OR

Power factor is the ratio of active power to the apparent power .

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 Significance of Power factor: 

1. P.F. increases current reduce so; cross section of conductor decreases hence its cost is educes. 

2. P.F. increases current reduce so, cross section of conductor decreases hence weight decreases. So design of supporting structure becomes lighter. 

3. Copper losses decreases, hence transmission efficiency increases. 

4. Voltage drop reduces, hence voltage regulation becomes better

5. Handling capacity (KW) of each equipment increases as p.f. increases.

6. Less capacity (KVA) rating of equipments are required so capital cost decreases. 


The condition for unity power factor:

When cosine of angle between voltage and current is zero.

When R = Z 

When KW = KVA 

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