the question is simple, based on what factors do I choose the right number of turns in field winding (for synchronous generator)?
It seems like the less turns there are, the more DC current is needed to sustain the magnetic field. Thus the lower limit is the current itself and generated heat (Assuming the winding is made of copper, not super-conductor).
Is there any upper limit then?
My (faint) idea:
Field winding on the rotor turns, therefore if I connect load to armature winding, there is magnetic field produced by armature winding itself. This can induce voltage in field winding and burn it (because the wire is not thick enough). But this idea seems incorrect, because the DC source for field winding would suffer from hude changes of Voltage during normal function.
Best Answer
basically the limiting factors are the physical properties of copper, it's bulk resistivity, thermal conductivity, and tensile streength.
make the wire too thin and it'll snap, or be so long that you'll need an impractically high voltage to achieve the desired field,
make he wire too fat and you need too much current..
more turns of thinner wire don't otherwise get you a stronger magnetic field for less input because the thinner wire has a higher resistance so you end up burning the same amount of energy in the field winding either way.