[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Math help...
Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, July 10, 2001 5:55 PM
Subject: Re: Math help...
Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
Tesla list wrote:
> Original poster: "John H. Couture by way of Terry Fritz
> Bert -
> I agree with your excellent comments below, however, I believe it should
> pointed out that the energy transfer in all magnetic circuits is 100%
> because there are no losses in magnetic circuits. Electric losses are only
> in electric circuits and the efficiency is the ratio of output/input.
Oops! There are PLENTY of losses in a magnetic circuit excited by AC
and operating anywhere near (say 50%) of the maximum flux density. Two
kinds of losses. Eddy current losses result from voltage being induced
in the core (just like in a shorted turn) thin sheets of steel help
this, as does use of high resistivity steel. Second, there is
hysteresis loss which is caused by the fact that the magnetization and
demagnetization curves aren't the same. Work has to be done to change
the direction of the magnetic field in the core. Hysteresis loss gets
worse as the saturation flux density is approached, and usually sets the
limit on the design.
If magnetic circuits were lossless transformers wouldn't warm up under
no load conditions.
My understanding is that with electric circuits currents flow in conductors
and resistance (ohms) create the losses. With magnetic circuits flux flows
in steel because of electromotive force and there are no flux losses. Eddy
currents flow in conductors and are electric circuit resistive losses.
Hysteresis is another matter but not involved with Tesla coils. Is this