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- To: Tesla List <tesla-at-pupman-dot-com>
- Subject: Re: Musein' and mathin'
- From: richard hull <rhull-at-richmond.infi-dot-net>
- Date: Thu, 13 Mar 1997 23:32:58 -0500 (EST)
>Richard wrote: > >> All, >> >> What follows is a long and perhaps for some, tedious diatribe, but is speaks >> to many points which I and others have labored over on this list in the last >> year or so. >[snip] >> Thus the peak current which we might expect in the tank is based on the peak >> capacitor voltage and the surge impedance. Such that... I peak = 21,000/50 or >> 420 amps From this we compute peak impulse power = 420 X 21000 = 8.82 >> megawatts!!!!! > > >Shouldn't that be MVARs (Mega-Volt Amps Reactive), as the V and I aren't in phase? >The MVARs in the primary, of course, do not represent the real power in the circuit. > > >> Now do we really believe that we get this out the top of the coil? Do we >> really even believe we really get this in the tank circuit? If we do we are >> six times a fool. Let's examine our wrong turns. Was the math wrong. Math >> is never wrong! Right? If the math is correct and based on solid physics >> and electrical concepts, where did we do wrong? >> >> Answer. >> >> It started at the wall plug and went down hill from there. The biggest part >> was the museins'- go back and count 'em. It continues with the assumptions. >> (count them too.) and finally the math and its application is flawed. Each >> equation taken by itself is rock solid and in an isolated ideal circuit >> (like in the stinkin' college lab) always solves out fine. But all these >> interact in a dynamic way that we did reckon or assume on. Pspice and its >> ilk can help here but then there are those nasty museins' and assumptions. >> This is were pspice and such programs can die on their mathematical vine. > > >It's true that even the best circuit simulator cannot make up for sloppy >circuit parameter modeling. No argument there. > > >> >> Richard Hull, TCBOR >> >> I still sorta think 3 megawatts peak is close. > > >That's about what PSPICE says my 20" (360kHZ) coil puts out, in VARs. >Say, you're not one of those closet PSPICE users, are you? > >-GL > >Greg, You are right, of course, about the Mvar bit. No I am not a closet Pspice type. I have played with Pspice on a friends CPU but found the endless input parameter requests and required assumptions to produce same a bit ludicrous, and told my fellow engineers in the department so. A good old time engineer who has a "feel" for many aspects of a situation might use Pspice to great advantage being a better guesser and more creative human input engine than a lot of the younger wild eyed chaps so taken with it. By the opposite qwerk most grizzled engineers are a bit anti-computer. I think the combination might be the ultimate match made in heaven. When I use the CPU it is because it is just another tool. Pspice, like anything else on the CPU, is not auto-erecting and talent is still required to formulate a good model followed by the grueling input machinations. Richard Hull, TCBOR
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