GATE Electrical Engineering (EE) 2018 Solved Paper

Question : 12 of 65

Marks: +1, -0

Two wattmeter method is used for measurement of power in a balanced three-phase load supplied from a balanced three-phase system. If one of the wattmeter reads half of the other (both positive), then the power factor of the load is

$0.532$
$0.632$
$0.707$
$0.866$

Validate

Solution:

In two Wattmeter method

\tan ϕ=\;{√{3}(W_{1}-W_{2})}/{(W_{1}+W_{2})}

Given:

W_{2}=\;{W_{1}}/{2}

\tan ϕ=\;{√{3}(W_{1}-{W_{1}}/{2})}/{(W_{1}+\;{W_{1}}/{2})}

ϕ \;\; =30^{∘}

\cos ϕ \;\; =\cos 30^{∘}=0.866

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