# A question on generators.

Discussion in 'General Electronics' started by dhanu, Oct 5, 2003.

1. ### dhanuGuest

Hello there,

I have this simple question on generator theory which is
bogging me down.

I know that the resistance of the field windings of a shunt
generators should be less than a certain critical resistance otherwise
the emf produced by the residual magnetism will not be sufficient to
develop any voltage in the generator.

Is there any minimum limit to the resistance also? Is there
any such limiting value of field resistance below which the resistance
should not decrease? If so, then what will happen if the resistance of
the field decreases below this minimum value.
Thank you in advance for responding.

2. ### Robert BaerGuest

Rubbish!
N turns of wire sweeping thru a given magnetic field at a given
velocity and angle will generate an EMF that can be calculated and has
absolutely *nothing* to do with the resistance of the wire.
Now if you want to draw current from that wire/winding, then the
current could be limited by the resistance of the winding (wire) along
with the resistance of the load.

As far as minimum resistance, if one uses silver wire, and maybe make
it rectangular in cross section so as to maximize packing factor (use of
space), then one could approach a minimum without use of superconductors
and cryogenics.