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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user