On Sat, Dec 26, 2015, at 06:02 PM, Bertho Stultiens wrote: > On 12/26/2015 11:53 PM, John Thornton wrote: > >>> Yes, that was my plan to run everything off of 120v except the VFD. > >> However, your drawing shows the VFD to be on the 120V side. > >> > >> I am a bit confused now which is on what and where. > > Ah the two 120v lines without a neutral is 240v, sorry if my drawing is > > confusing. That's why I labeled them L1 and L2 instead of L1 and N. > > Are you using two phases (L1 + L2) of a three phase system or are you > actually using a one-phase system (L1 + N). > > There is quite a big difference between the two scenarios. > > The voltage between any two phases in a three phase system is sqrt(3) > times the voltage between neutral and any single phase. >
I believe the answer is "neither". I think he's using the American standard 120/240V split single phase system. The distribution transformer has a 240V single phase secondary with a center tap. The tap is grounded, and is the Neutral. The two ends are L1 and L2. 120V volt loads (all "ordinary" residential loads such as lights and small appliances) are connected between either L1 or L2 and Neutral. The panels are designed so that roughly half the total load is on each side. 240V loads (electric stoves, electric dryers, central air conditioners) are connected from L1 to L2. Sometimes there is a neutral (for modest 120V loads), sometimes there isn't. This drawing shows some of the plugs that are used: https://en.wikipedia.org/wiki/NEMA_plug#/media/File:NEMA_simplified_pins.svg The 120/240V split single phase system is the norm for American residential power. Three phase in a residence is extremely uncommon. John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
