- #1

Physicist3

- 104

- 0

starting with the beginning, if the magnetic flux varies sinusoidal, then the flux at one instant would be;

∅ = ∅

_{m}sin(ωt) (I have been told this should be done in degrees and not radians?)

value of induced emf in core at any time (t) =

[itex]\frac{d∅}{dt}[/itex] = ω∅

_{m}cos(ωt)

Am I correct in saying that from this second equation, ωθ

_{m}= E

_{m}(Max induced EMF in core)?

If E

_{s}= rms value of emf induced in core, this = [itex]\frac{1}{\sqrt{2}}[/itex]ω∅

_{m}= [itex]\sqrt{2}[/itex]∏f∅

_{m}= [itex]\sqrt{2}[/itex]∏f(AB

_{m})

Eddy current Power Losses = [itex]\frac{E

_{s}

^{2}}{R

_{s}}[/itex]

= [itex]\frac{2*∏

^{2}*f

^{2}*A

^{2}*B

_{m}

^{2}}{R

_{s}}[/itex]

The next bit is the section of the notes that seems to confuse me,

Eddy current Power Loss = P

_{E}= K

_{E}*f

^{2}*B

_{M}

^{2}, where K

_{E}= Constant = 2*∏

^{2}*A

^{2}/R

_{s}.

The book then says 'hence eddy current losses = α (f

^{2}*B

_{M}

^{2})

Does this mean that K

_{E}is the same as α and eddy current power loss is the same as eddy current loss, or are these two different things? As far as I can see they appear the same but I just wanted to make sure from someone who has a bit more experience or knowledge of this.

thanks