Solve Resistance per unit in simple problem

Question

I'm just learning basic electronic. I don't understand this simple problem.

A 400 ohm resistor carries a current of 60 Ampers.

resistance is R per unit (pu) = 400ohm/32ohm = 12.5

how can I obtain this 32 ohm? I have no idea where it come from.

EDIT: This is a resolved problem with resolved exercices, the thing is that I don't understand how to get some values, the process I mean.

We have no idea either, as your question doesn't mention it. — Dzarda, Jul 22 '14 at 19:53
So, is that 32 Ohms per meter, perhaps? So you have a 400 Ohm resistor with a length of 400/32 = 12.5 meters? You really should elaborate more. — sherrellbc, Jul 22 '14 at 19:56

score 1 · Answer 1 · answered Jul 22 '14 at 20:03

1

per unit designation is a power systems engineering principal that allows for easy transformation/scaling.

In this case, the resistance is scaled against a base resistance of 32 \$\Omega\$ which would be defined from \$\dfrac{base volts}{base amps}\$

answered Jul 22 '14 at 20:03

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I don't understand. Could you be more precise? You mean that the default resistence is 32 Ω? – MarcoGarzini Jul 22 '14 at 20:25
@MarcoGarzini here is something from Wikipedia that I found http://en.wikipedia.org/wiki/Per-unit_system – placeholder Jul 22 '14 at 20:33

1 Answers1