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Me and my engineer have been talking about the advantages of ducted fans verses open blade fans.On my larger buzz box I threw a metal shroud or duct around the fan inside the welder and greatly increased the air flow over the transformer. I don't use it at full power but it still never gets any where close to being what I would consider hot. Now I know why.After taking to some one who always puts numbers to things I found out how big a difference it can make.It turns out adding ducting around a fan can increase air moving efficiency up to 94%.So if you have a welding machine that just beats and remixes the air around the inside of your machine and wonder why it runs hot, now you know.A open at both ends hat shaped duct and shroud can direct air over your welders transformer and separate hot transformer air from cooler incoming air.Adding a duct and fan shroud will make your 20% duty cycle buzz box a 50% duty cycle heavy industrial machine but it wont hurt.Also I added a fan switch to run the fan with the transformer deenergized. I Figure a dead transformer will cool faster than a live one. I like to get in the habit of cutting power when I put the stinger down.As a conductors heat increases electron mobility decreases so as the lump of copper in your machine heats up the amps start to drop off, also magnetic properties of the transformer core become less desirable as temperature increases. Even if you don't max your welder out and run it so hot you have to bump up the amp setting after a while, improved cooling can increase weld consistency.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:good idea, i'm sold to it but Why the props on planes and boat are not ducted
Reply:Air boats are usally ducted more for safety, low speed performance is improved too.This is why you see air ships with ducted fans.For under water use tug boat and scuba diver thrusters are often ducted.For lower speed operations once the vehicle is moving the air, flow through the prop smooths out. As forward speed increases the duct around the fan becomes more of a restriction. This goes for air or water.Helicopters and small fans suffer from something called vortex ring state where the blades suck up turbulent air and it stalls the flow through them. With small fans you throw a duct around them, helos you put a really big rotor with a lot of power under it to over come vortex ring state.Ducting on high bypass turbo fan jet engines are a whole nother animal, its more like directing compressed hot air.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:Wasting your time and money we had over 50 - 500 amp Hollup welders AC, the fans burned out and they ran for years with no problem .
Reply:Never heard of a Hollup. Now I'm curious. Were they rebadged Millers?I could see a ducted fan working on a marginal consumer welder though.
Reply:If they were 500 amp welders were you using them any where near 500 amps?Since I have the fans on their own switch I don't bother to run the fan on the big craftsman if I run it at 130 amps or less intermittently.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:Most of the old school transformer welders run their fans all the time the machine is powered.
Reply:Originally Posted by farmallMost of the old school transformer welders run their fans all the time the machine is powered.
Reply:Of course, but with the larger beasts the drain of the fan is trivial by comparison to running them under load. For hobby use (the only place an off switch would matter) they would rarely be run long enough to influence an electric bill much compared to tools such as air compressors. I didn't notice any difference I could attribute to my Miller 340 (570A max output of one feeds it 100A in) for home shop use off a 50A breaker. (Finally managed to trip the 50 when running .045" flux core off a suitcase feeder but it took a while and didn't repeat.) The fan is also a useful reminder not to leave the machine powered up, and it ventilates the 40' ISO container it's in nicely!
Reply:I drilled a hole in the face plate and added a couple of panel lights that are on when the transformer is hot.I added 2 lights to remove the possibility of a single light burning out and giving a false transformer off indication.The panel light is good because I will work till after its dark some times and with ear plugs I can't hear the fan going.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:Originally Posted by mad welder 4Helicopters and small fans suffer from something called vortex ring state where the blades suck up turbulent air and it stalls the flow through them. With small fans you throw a duct around them, helos you put a really big rotor with a lot of power under it to over come vortex ring state.
Reply:Originally Posted by mad welder 4... Helicopters and small fans suffer from something called vortex ring state where the blades suck up turbulent air and it stalls the flow through them...
Reply:Originally Posted by OldendumSimilar thing happens in traffic circles at rush hour. |
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发表于 2021-8-31 22:36:32