- #316
jim hardy
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sorry for format , computer going flooey again , highlight and reply has quit working.
It's a balance between applied rectified supply voltage trying to drive the core into saturation
and control current trying to keep it from saturating.
UP and DOWN is relative, just directions on a graph.
Remember this one from 202?
Flux started from zero and applied voltage was sufficient volt-seconds to saturate .
Remember , rectified supply's volt-seconds drove flux UP on this graph.
If a control winding had applied bias so we started from nonzero negative flux, well below zero, flux would not have got to saturation point.
jim hardy said: ↑
Core loss per pound goes up but pounds of core went down... What's exponent of B in loss term ?
Tim said
Sorry what do you mean the 'exponent of B in loss term'? I don't understand what youre asking, sorry.
The question was
in 308 "-so when you take some steel out, the core loss propably goes up, does the copper loss change?"
and my answer was " At higher B, because flux is same but area is smaller, let's think about core losses.
Steinmetz expressed them in Watts per Pound.
So if you remove 10% of your iron by reducing ts area to 0.9, you have increased B by ratio 1/0.9 = 1.11111 .
So watts per pound went up but how much ?
If in direct proportion to B, ie by 1/0.9 it's a wash, 1.111... watts per pound X 1/1.111... pounds = 1 . Core loss is unchanged.
But i remember seeing core loss in proportion to B1.4 or something.
So probably yes , core loss went up because (1/0.9)1.4 = 1.159X more per pound X 0.9 = 1..04
4% more core loss?
Also, did you mention the change in copper loss?
I remember intending to but did i ? I sure don't know !.
Copper loss remains I2R , your turns can be shorter by however much you reduce the circumference of the core, roughly √Δdiameter. So R decreases a little. Magnetizing current goes up a little so I^2 does too. But these effects are small... try some numbers.
jim hardy said: ↑
without something to prevent it, saturation will follow from application of rectified AC.
I'll look for that i think i searched on Fourier rectified
Tim said
But what I'm asking is, is THAT the actual mechanism by which Steiner designed his Amp to operate, the operation principal of the amplification: it is the force that pushes it the flux down, and allows him to bring it back up again, restorting dΦ/dt to block the current off?
those words confuse me.it is the force that pushes it the flux down, and allows him to bring it back up again,
It's a balance between applied rectified supply voltage trying to drive the core into saturation
and control current trying to keep it from saturating.
UP and DOWN is relative, just directions on a graph.
Remember this one from 202?
Flux started from zero and applied voltage was sufficient volt-seconds to saturate .
Remember , rectified supply's volt-seconds drove flux UP on this graph.
If a control winding had applied bias so we started from nonzero negative flux, well below zero, flux would not have got to saturation point.