From the following transformer, how would I calculate:a) the equivalent impedance on the low-voltage sideb) Converting the impedance found in (a) to it's per-unit quantities
a) the turns ratio of the transformer is 20 to1 so to refer an HV side impedance to the LV side you divide it by the square of the turns ratio which in this case is 400 which gives: 0.001+j0.00025 ohms. b) There's a certain amount of freedom in doing this for you may define the per-unit impedance base however you want. It is however rather usual to define it as VA / I^2. Here I 5000/2400 2.083 amps So base impedance HV side 5000/2.83? 624 ohms making the given impedance (0.4+j0.1)/624 p.u. This p.u. value should be the same on either side of the transformer. Nice to see you around again but do I notice you haven't improved at saying please when you want someone to do something for you for nothing. If you can't learn that there's not much use in learning all these technical skills. You're going to remain a clumsy oaf!
