Like many Hambs my son is gradually building his tool inventory up in his dream garage. He has some nice stuff already, but there are always additions waiting to be acquired. Continually older equipment becomes available and lots of it are of industrial quality..........meaning 3 phase. Lots of times this type of equipment gets passed over because of the 3 phase. The "current" darling for converting seems to be the "variable frequency drive". My son has already done this on his lathe and is familiar with the process. I however am old school (dense) and now we have acquired a Powematic Model 87 vertical band saw, I want to install a single phase 220/3 hp Dayton motor which I already have. The Powermatic has a 220 volt blade welder mounted on it..........which I believe is single phase. It also has a 110 volt light on it..........which I know is single phase. So one thing that confuses me is that with a normal 220 volt SINGLE phase, you have two 110 volt hot wires incoming and one "neutral" wire. 110 x 2 = 220 So, a 220 volt THREE phase has 3 incoming hot wires and a neutral wire. So, are each of those incoming wires 110 volts ? If so, how does that end up being 220 volts? Am I just wrong about this? My reason for asking this has to do with the "blade welder". Its easy enough for me to convert the main drive motor to single phase and wire it up........but I also want the blade welder to work. If its single phase (as I think) then they must only be using 2 of the 3 three phase wires and they must be delivering 110 volts. If they are delivering less than 110 volts each, then I have a problem. I have been unable to find a wiring diagram for the Powermatic 87 or the Model 600 blade welder. I'm going to try to trace some wires today and see if I can figure it out. Son needs to cut some sheetmetal for his 56 Chevy truck he's building, so I'm holding him up..........
You only need the neutral if you need to get 110/120 volts. Straight 220 (or 208) won't use the neutral at all. Each hot will read the lower voltage to the neutral, but the higher voltage between the hots only except as noted below. I'll note you should have a ground, which isn't the same thing even though they may be connected at the same point at the panel. It's VERY important that you keep these separate after leaving the panel. If you need a neutral, also run a ground wire, don't try to combine them. You may have an issue with voltage. While there are multiple types of three-phase connections, the most common ones are Delta and Star (AKA Wye) connections. Delta connections are rare anymore, the power companies don't like them and they limit you for the lower voltage loads plus making load balancing problematic. In a Delta connection, you have 220 between each hot, but can access 110 between only two of the three phases, the third leg will be 'high' (208V) to the neutral. The Wye connection doesn't have this limit, you can get 110 between any of the three phases and the neutral but the high voltage will only be 208, not 220. This is caused by the vector sums of the voltage. This may or may not be an issue, you'll need to check the individual pieces to see if they can safely operate at 208. Most can, but not all. Given the electronic trickery available in some of those frequency drives, you may be able to 'correct' this in the set-up but that's something you'll have to check on.
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