On 15/03/17 16:15, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 15:14:56 +1100, James
wrote:

On 15/03/17 13:43, Jeff Liebermann wrote:
On Tue, 14 Mar 2017 07:54:26 -0700, Joerg
wrote:

On 2017-03-13 20:00, Jeff Liebermann wrote:
On Mon, 13 Mar 2017 12:38:07 -0700, Joerg
wrote:
55V at 500mA. This is encouraging.

That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I
converted 136 km/hr and found that it was 84.5 mph. With a rocket
assisted bicycle, I might be able to do that.

Well, yeah, they just wanted to see where the limit is. I guess the
enameled copper wire inside would smoke out if you kept that speed for long.

Only the resistive part dissipates power in the wi
P = I^2 * R = 0.5^2 * 2 = 0.5 watts
So, it won't be the wire that gets hot. However, the cores in
saturation are going to get warm. Offhand, I don't know how to
calculate how hot.

Do you mean eddy currents in the core?

Nope. I meant hysteresis losses. Eddy currents do contribute to
losses by "bucking" the build up and collapse of the magnetic field,
but most of the heat is produced by hysteresis losses:
https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur
See an induction heater or stove for an extreme case of heat being
generated by eddy and hysteresis currents:
https://en.wikipedia.org/wiki/Induction_heating




Hysteresis losses are different from saturation. Saturation shouldn't
occur if the core has been adequately designed to accommodate all the
permanent magnet flux & MMF.

--
JS