Ip= 19A at Vp = 440V and Vs= 9000V. If the transformer is 95%efficient, how many turns are in the secondary coil? (efficiency eis the ratio of the power output to the power input or e = Ps/Pp).I know the result is Ns= (Vs Np) / Vp = 3680turns, but why can't I use this below equation:
Ps/Pp = (Is Vs) / (Ip Vp) = 0.95
Is/Ip = Np/Ns
we have Np Vs / Ns Vp = 0.95
Ns= (Vs Np) / (0.95 Vp)
So why can't I use this equation [ Ns= (Vs Np) / (0.95Vp) ] to find secondary coil.
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Could you please draw a diagram of this case. Pleaseexplain why I = 240V / (R + r) ? Where does r come from and whatformula is this? a 240-V dc motor has an armature whoseresistance is 1.8 ohms. When running at its operating speed, itdraws a current of 14.0 A. Starting current is 133 A. What seriesresistance would be required to limit the starting current to 26.0A? Could you also explain what is a back emf with simpledefinition? why does it act against applied voltage and reduce thecurrent?
