Re: 3 phase power (was Re: Wireless home LAN - WiFi vs Bluetooth?
On Thu, 01 Aug 2019 12:48:32 -0400
Doug McGarrett <dmcgarrett@optonline.net> wrote:
> On 07/31/2019 09:08 PM, rhkramer@gmail.com wrote:
> > An update | correction | recollection ;-)
> >
> > On Tuesday, July 30, 2019 11:34:43 AM rhkramer@gmail.com wrote:
> >> I have seen diagrams in NEC code books for a different arrangement
> >> to get 120 volt 3 phase power, but I don't recall ever actually
> >> encountering that in real life.
> >
> > Oh, wow, how quickly I forget -- I did encounter systems like that,
> > often for lighting in industrial applications, And, further, iirc,
> > we could (and did) buy and install florescent light (and maybe
> > HID?) fixtures designed to work on 208 volts, which we connected
> > phase to phase in that kind of system.
> >
> > Of course, I could be misremembering.
> >
> >> In that case, iirc, 120 volt loads are connected from a hot
> >> tap to the neutral wire (the 4th wire of the 3 phase arrangement),
> >> and you get (nominally) 208 volts (RMS) connecting phase to
> >> phase. I have seen things like motors that were rated like 240 /
> >> 208 volts (or something like that).
> >
> >
> Three-phase power comes in two varieties: delta and wye (Y). In
> delta, there are only three wires, and you get power across any two
> of the three phases. In the wye configuration, you get power from one
> phase of the three to the center of the wye.
> If I remember right, and I'm not sure I do, you get 208 VAC across two
> points of the delta, and I THINK you get 120 VAC from an end point to
> the center of the wye.
>
Yes, because over here it's 240V and 415.7V. Between phases is the
phase-to-neutral voltage multiplied by the square root of 3.
--
Joe
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