On Thursday, March 10, 2011 01:13:26 AM Jon Elson did opine: > gene heskett wrote: > > On Wednesday, March 09, 2011 08:02:40 PM Jon Elson did opine: > >> The current draw of > >> > >> a 100 Hp motor on 240 V is about 330 A per line! Yikes, the > >> transistors must be the size of a brick! > >> > >> > >> Jon > > > > I am wondering where you got those figures Jon? > > OK, I was extrapolating from a 1 Hp Bridgeport motor, which is rated at > 3.3 A at 240 V. Obviously, there is an efficiency scaling factor I > didn't take into account for larger motors. > > Jon > I don't know as I'd say it was obvious, but in comparison to a 120 volt 1/4 horse single phase capacitor start, which on most nameplates draws about 4.6 amps for that 1/4 horse, there must be an efficiency of scale that is not directly related to the single phase vs 3 phase condition. That is a big hit all by itself.
The motor in question did not get so warm that you could not rest your hand on it at the end of a 19 hour broadcast day unless you had sensitive hands. At one point, while fighting with the linkage timing of one of those modutrol motors, I actually sat on it, 7 feet up in the air, for about 45 minutes while attempting to adjust the linkage to get a quasi-linear response in the air flow allowed so the coolant didn't get too cold and viscous to flow through those $150,000 klystrons, who have a very picky appetite when you already have a 25% (absolute max 30% else it gets too stiff to pump well) mix of pure, technical grade E-glycol in the system, and its 15F below the freezing point of that mix on the other side of the wall, so we have to restrict the airflow under those conditions to keep it flowing well. We often left the pumps running all night with the louvers closed as the pumping losses kept it up to about 80F when the blowers were off. With nearly 200 kw worth of heat, and a 250 gallon storage tank, we could apply beam power and open the louvers with the same signal, the louvers would start to open and open too fast so the coolant dropped about 60F, then as the louvers got some feedback and closed to just a crack, and in about an hour it would get back up to about 65F in the tank. This is HVAC tech, and it is not well publicized or taught, that a multivane louver flows about 50% of is max flow, when only opened about 8%, so you normally adjust the arms on the modutrol so that the off position is pointed directly down the connecting rod to the louvers lever, which is at that point nearly 90 degrees to the rod. So the first 10 degrees of modutrol motion only opens the louver 1 or 2%, then at the other end of the travel, wide open, the louver arm should point pretty close to straight down the coupling rod so the last 10% of the modutrol's motion takes the louver from about 30% open to wide open. Anything less than that setup, the temps will overshoot and the whole thing oscillates at about one cycle every 2 to 3 minutes since the modutrols take 90 seconds to run end to end. Your trivia lesson for today. ;) -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> I saw a subliminal advertising executive, but only for a second. -- Steven Wright ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
