06-26-14, 01:38 PM | #21 |
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Hey .98 is good for any motor. I cant get most of mine much above .90pf.
I power factor corrected my small 110v powered 100amp out put craftsman arc welder. At no load it goes from .30pf to .75pf with the addition of a 50uf capacitor. Under load I expect the pf to go up to some where around .90pf. I used 40, 50, 55, 60 and 80uf capacitors to test it out. The capacitor is just sitting on top of the machine, I have not installed it. Hopefully I can make it fit in there with all the DC output stuff and ducted fan I added. I rather not attach it to the out side since I want to keep this machine portable and self contained. On my full sized 240v powered arc welder I tested out those very large mallory power factor correction capacitors I salvaged. They worked better than the two 80uf motor run capacitors. I will sling the mallory capacitors up under my large machine. Since for some reason two 60uf capacitors wired L to N gives the same performance as a single 40uf capacitor wired L to L. I have been getting very good performance out of two 55uf capacitors wired L to N. |
07-01-14, 12:40 AM | #22 |
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Next PF correction project will be to do a mild pfc on my trouble some oilless air compressor that runs a .44pf at full load. It will pop a 15amp breaker on all but the coolest days.
I am selling it to my friend who says he would really appreciate it if I could make it not consistently pop a 15amp circuit breaker, he has barrowed it before. I guess he has or has used it on a breaker box full of 15s. Challenge accepted. Bet I can trim at least 3 or 4 amps of draw. In other news... I installed the 50uf 440v motor run capacitor with MOV protection inside my small arc welder. It barely fit. Next test will be to see if it corporates with my small generator any better. The capacitor will save about 2 amps, which could be huge to this small generator. Now this little welding machine weighs about 50 pounds with all the stuff I added. Bridge rectifiers, heat sinks, 2 good sized inductors, PFC cap. Last edited by oil pan 4; 08-15-15 at 05:17 PM.. |
07-01-14, 02:54 AM | #23 |
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My refrigerators power factor is 0.98
I believe they charge industry extra $ for the low power factor of equipment/electric motors and whatnot. I'm not sure if is still true today with the high tech meters but it was. |
07-01-14, 11:51 AM | #24 |
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Is there any worry about the life of these capacitors?
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07-01-14, 01:32 PM | #25 |
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Yes there is major concern for the life of the capacitors in non motor applications.
These capacitors are all rated for 370 to 440 volts and it turns out motor run capacitors work really well on motor applications L to N and L to L. They dont work so well connected line to line (only 240 volts) on stick welders. Seems that motor run capacitors burn out after a few seconds of arc welding when connected line to line with out MOV protection. I have used motor run capacitors in my stick welder wired line to neutral with out MOVs and have burned 20 pounds of electrode with out any problems. I have since upgraded the stick welder to actual pfc capacitors rated for 480v, wired them L to N and then gave them MOV protection. Dont think I will have any more problems. Last edited by oil pan 4; 07-01-14 at 01:37 PM.. |
07-06-14, 01:11 AM | #26 |
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I partially power factor corrected my .44pf oilless air compressor for my friend. Its a compact little rig, there is only room for one capacitor. Knowing how bad the power factor is I know it will need way over 100uf to give it an ideal power factor correction.
I warmed up the compressor for a couple minutes and did a baseline, compressor shut off at 16 amps. I added an 80uf capacitor to the circuit (just to help quantify added capacitance to amp reduction), that dropped amps to 13.8 at shut off. Then removed the 80uf cap and put a 100uf capacitor into the circuit. That dropped the amps at shut off to 13.30amps. That brought the pf from .44 up to .60pf and should keep this machine from tripping a 15 amp breaker when used on hot days for extended runs or when on an extension cord. Good enough I guess... Now some one made me an offer for my 3 power factor capacitors, so I will pull the 2 I put in my welder and go back to motor run capacitors. Last edited by oil pan 4; 07-06-14 at 01:39 AM.. |
07-07-14, 12:20 AM | #27 |
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I installed a 0 to 300volt gauge with the MOVs hooked up inside the gauges handy box. MOVs are connected L to N since radio shack stocks big cheap120vac MOVs.
The gauge and MOVs are hot when ever the machine has power. I installed a volt meter because my machine runs perfectly at home, because at home its got a sub panel at the service drop, but when I take it mobile some times it acts strange like its losing a lot of power. I will be connected to a 50 amp circuit but who knows that "50 amp circuit" could be 60ft long and made of 8ga wire or I could be on 2 legs of a 3 phase connection only getting 208v. If I am on 208 I will know right away, if on a circuit made of a long run of under sized wire I will set the machine to 100 amps, connect 2 work leads and short curcuit it through the work and see how much input volts drop. |
08-08-14, 10:19 PM | #28 |
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I built another one. I found a kind of old 1.5hp "speedy air" made by Dayton, in Ohio. I wanted to make this a mobile 220 volt compressor. (my other garage bound air compressors never see the light of day and don't have wheels) I got this one from the scrap yard. The pressure switch had corroded and was open so the genius that owned it last hot wired it so the compressor switch runs when ever the machine is plugged in. There was no way the machine would ever build up to any where near shut off pressure on any 120v circuit that was any where near being up to code.
The machine was hot wired for 120v and drew 20 amps (at about 1000watts, a horrible P.F.) just turning the compressor with the tank wide open. I am thinking the people trashed it because the pressure switch was bad (A $20 fix) and I know it flipped the breaker as soon as it started to build pressure since it was drawing almost 21 amps at no load at full load, based off what it used for 220 it would draw nearly 40 amps at shut off had it been left wired up for 120v power. That's bad because the max rated amps on the side of the motor says 22 amps for 120v power (and 11 amps when wired for 220). So I switched a few wires around according to the diagram on the side of the motor, converting it to 220v and installed my favorite 220 volt power connector the NEMA 10-30 clothes dryer power cord. So now converted over to 220 at no load it was running about 9 amps. With no capacitor running a wildly lagging power factor it was hitting 18 amps at shutoff pressure. A little high. I knew it would need around 100uf so I installed a temco 440v 100uf motor run capacitor in parallel to the motor assembly. That dropped the amps down to right about 10 amps even at shut off. Figuring less may be more I switched over to a Dayton 80uf 370v motor run capacitor. That only increased amps to 10.20 to 10.30 at shut off. That tells me 100uf was on the verge of being too much capacitor. Then to test what a much smaller capacitor would do I put a 440v temco 40uf on there, and amps went up to 13 at shut off. I did this 220v power factor correction shooting from the hip, just using my fluke324 amp clamp meter. I have a 220v single phase energy meter that will display P.F. but I have not bothered to rig it up yet. This machine I want it to have a slightly lagging P.F. since it is a mobile unit and will be powered by a generator at some point. This one has wheels and a handle. But I know some of you are thinking "10amps of 220 is way more than 1.5hp". Yeah the motor gets a little warmish but it will survive. |
03-05-15, 02:06 PM | #29 |
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The primaries and secondary's are insulated from each other. I already tested that.
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08-15-15, 07:45 PM | #30 |
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I needed a tig welder so instead of spending $1500 on a decent miller or rolling the dice on made in china garbage I added a tig torch to my AC only craftsman welder I original bought for $100. I converted it to DC for around $50 then picked up a tig torch plus consumables for about $250.
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apparent power, kva, power factor, true power, welder |
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