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oil pan 4 · 08-08-14, 09:19 PM

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.

08-08-14, 09:19 PM	#28
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	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.