SSE JE Electrical Engineering 28 Oct 2020 Shift 1 Papers

Question : 194 of 200

Marks: +1, -0

For a single-phase motor of 2 HP rating, supply voltage is 240 V ac. If the efficiency is 70% and power factor is 0.8, find the input current.

19.95 A
15.95 A
10.95 A
17.95 A

Validate

Solution:

Output power rating of single phase Induction motor = 2 HP = 2 × 746 W = 1492 W.
Supply voltage (V) = 240 V
Efficiency (η) = 70 % = 0.7
Power factor (cos ϕ) = 0.8

\η={\text " Output power "}/{\text "Input power "}

\text "Input Power (P)"= \text "Output power"/\η

=1492/0.7=2131.43\W

Now

\P = \V × \I × \cos \ϕ

2131.43 = 240 × \I × 0.8

\I = 11.1 \A

So our closest possible answer is 10.95 A.

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