- #1
michaelplease
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Homework Statement
A step-down transformer going from 240 V to 12 V is 95% efficient. The input current is 20 A.
a) Determine the primary turns: secondary turns ratio necessary in order to maintain a 12V output.
b) Determine the output current.
I have solved it as if I needed an secondary output of 12 * (100/95) = 12.6 V. But what I am wondering about is whether the 5% loss of power causes a 5% loss in secondary voltage, or a 5% loss in secondary current, or a loss in both that multiplies up to 5%, and why. Could someone please explain?
Homework Equations
P = IV
Np/Ns = Vp/Vs
The Attempt at a Solution
a) Vs = 12V * (100/95) = 12.6V
Np/Ns = Vp/Vs
= 240 / 12.6
= 19 : 1
b) Pp = IpVp
= 240(20)
= 4800W
Ps = Pp (0.95)
= 4560 W
Ps = IsVs
4560 = (12)(I)
I = 380 A