On Wednesday 20 May 2009, Joerg wrote: >Gene Heskett wrote: >> On Wednesday 20 May 2009, Joerg wrote: >>> DJ Delorie wrote: >>>> Levente Kovacs <leventel...@gmail.com> writes: >>>>> 230V times 100A is something I dont want to even calculate. >>>> >>>> It's 23000 :-) >>>> >>>> My air conditioner draws 123 amps at 240 volts for the first few >>>> seconds. That's almost 30kW. >>> >>> Seconds and not fractions or a second? Yikes! Unless it's a 10-15 ton >>> unit that doesn't sound normal. Did you find some of the power hogs with >>> your new board by now? >> >> Off topic reply, but could be germain too. >> >> Not even a 40 horse compressor in a 22 ton (rated, yeah sure) Lennox will >> draw that much for that long. Its startup was a peak in the 250 >> amps/phase area, and the reason I say area is that a std 400 amp scale on >> an amp-probe on any phase line swung up to 250 and back down to its >> running of about 39 amps/phase in a purely ballistic fashion as the >> startup surge was only 6 or 7 cycles of the 208/3 phase line. >> >> Now it really gets off-topic. >> >> That was one of those _must_ _work_ units else a tv station was off the >> air 10 (or less) minutes after it failed. It was also probably >> responsible for some of the early ozone holes over the antarctic as it was >> severely under fanned on the condensor side, and I had to add 20 pounds of >> freon in the fall to keep it working right until it wasn't needed, and >> bleed that 20 pounds back off as spring turned into summer. This went on >> for 8 years on my watch, back in the 70's, and long before they started >> regulating all that stuff. >> >> 2 ea. 1100rpm 1/2 horse motors turning 24" fans just didn't cut it. I got >> tired of that one spring and fixed _some_ of it by taking a failed motor >> to town, having the brackets stretched to carry 2 horse 1800 rpm motors, >> replacing the motor with a 2 horse 1800 and repeating it the next week >> with the second one. 2 horse wasn't quite enough as they ran a couple of >> amps over nameplate when the condensor was relatively clean. When those >> blades failed (fatigue cracks, caught before they made shrapnel), I >> replaced them with blades with an inch less pitch. That allowed it to >> continue to work until the ambient went over 80 degrees without bleeding >> freon to keep the high side under 400 psi and the compressor currents >> under 43 amps/phase else the overcurrents in the compressor would trip. >> Based on those results, I would have said that a single 20hp motor, >> running at full load pulling a quad torrington wheel with each half about >> 16" wide & 14" diameter, would have been about right. That could have >> been throttled with a 4' square louver driven by a M-H proportional >> control Modutrol to regulate the high side pressures/temps and made it >> work all year. Some of the crappy designs foisted off on the industry by >> supposedly reputable, old line makers are amazingly loaded with excrement. >> I even called Lennox and they swore on a stack of bibles that those 2, >> 1/2 horse motors were enough. I asked what was the expected operating >> temperature range and he said 75-90F outside. I said "and what happens >> when you have enough heat load to need it, but the outside temp is 33F?" >> "Its not designed to run at those temps." Why did you sell it to the >> State of Nebraska then, you did have the specs, I've seen them? Mumble. >> >> Obviously I wasn't talking to a real engineer so I asked him where he got >> his sheepskin. More mumbling. >> >> Being a tv engineer for the state NETV commission, when the nearest help >> is 200 miles away in Star City, (Lincoln NE) means you truly are a Jack Of >> All Trades. :) Those 8 years were _very_ educational, but I left because >> I was still not the lead dog, so the scenery never changed. :) > >Thanks for sharing, that was a real story from the trenches. > >Not looking forward to the 105F days that are coming. I don't need A/C >even when it gets to 95F in the office but when visitors come I have to. >And then the compressor often goes into bypass mode making that awful >rarrrrr noise. Then it's waiting 5-10 mins, crossing fingers, make sure >no black cat crosses street from right to left, turn switch to the old >Lennox back on, hold breath.
Then it needs help like I've described. That sort of a locked rotor shutdown is pure hell on the compressors. No other nice way to describe it unforch. -- 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) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> "Oh no, not again." - A bowl of petunias on it's way to certain death. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user