How to determine what the input (or output) voltage and/or power of a transformer is?

Question

based on the transformer physical design like the size of its components?

Without reading the catalog!

Answer 1

You can roughly determine the power by looking at the size and weight of the core.  You can also make a good guess as to whether it is a 50/60 Hz or 400 Hz transformer by looking at the core material and the application.  

I have seen tables in older reference books (Radio Amateurs handbook and others) that chart core-weight versus power for power transformers, and core-volume versus power.  But, I don't have access to that information right, now, and a Google search would take a long time.  But the information is out there.

As for the voltages on the windings, that cannot be 'seen' for 'felt'.  It must be measured, and fortunately that is something that can easily be done.

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Answer 2

Astrological things will not work out in electrical components.

If the bushings of the transformer is outside visible then u can assume the voltage level by counting the number of discs in the bushing each designed for 12kV.

But believe me,it is difficult or not possible to conclude the voltage level and power rating of a transformer with out reading its name plate

Answer 3

ok am guessing u mean a small household applications-common transformer right??

try any information mentioned on the transformer? none?

then i think u cud find out by observing the ratings of the circuit components connected to the secondry side, this will show u the secondary side voltage hopefully. but about the input i cant think of a sneaky way to guess that.

if it has a catalogue then read only the ratings part, it wont cost u much time, not more than reading this same answer!!!

good luck and get back here again if any more help, but plz be more clearer.