The primary of a transformer has 400 turns while the secondary has 2000 turns. If the power output from the secondary at 1000 V is 12 kW . The resistance of the primary is 0.2Ω and that of the seconda

Question

The primary of a transformer has 400 turns while the secondary has 2000 turns. If the power output from the secondary at 1000 V is 12 kW . The resistance of the primary is 0.2Ω and that of the secondary is 2Ω . If the efficiency of the transformer is 80% , then the power loss in the primary is

TestHub · Accepted Answer

N p ​ = 400 , N s ​ = 2000 and E s ​ = 1000 V Now, E s ​ E p ​ ​ = N s ​ N p ​ ​ or E p ​ = N s ​ E s ​ × N p ​ ​ = 2000 1000 × 400 ​ = 200 V Since the efficiency is 80% , the input power is 12 kW × 80 100 ​ = 15 kW ∴ Current in the primary is I p ​ ​ = Input voltage Input power ​ = 200 V 15 kW ​ = 200 15 × 1000 ​ = 75 A ​ ∴ Power loss in primary = I ρ 2 ​ R ρ ​ = ( 75 ) 2 × 0.2 ​ = 1125 W = 1.125 kW = 1125 W ​

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