"Brandon Anderson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I can only think that your question is aimed at determining, after a
> spider box, which phase an outlet is running off of. If this is so,
> turn off the box and unplug a single phase completely. Turn it on,
> and if it no longer works, you got your phase. If that's not the
> question, then I'll just give you some info on electricity to help
> with whatever you are doing...
>
> Power is sent through three conductors from the power plant and is
> stepped down at a series of delta transformers until it gets to the
> entrance of a building or a neighborhood.
----------
One question - where do you live? In most parts of the world including the
US, transformers used for 3 phase are mostly star delta. There are
operational and economic advantages to this with respect to delta delta.
For example, any appreciable length of overhead line fed or connected only
to delta windings, can be trouble (this was found by experience, back in the
1920's).
--
Don Kelly @shawcross.ca
remove the X to answer
----------------------------
At this location, a couple
> of things could happen:
> 1. A delta transformer steps down to 240vRMS (US) with a center tap
> per phase neutral, grounded at that location. This allows for either
> two 120v hots relative to neutral, or 240v relative to each other.
> 2. A Wye transformer steps down to 120vRMS (US) and generates a
> common neutral at the center, grounded at that location.
>
> Once this is done, an added safety ground, grounded away from the
> neutral, is installed, and the system becomes either five or ten wire
> (the delta has three feeds per phase plus ground). Usually the delta
> method will then distribute the feeds so that they enter the home or
> office as either 3 or 4 wire (depends on if the ground is local or
> remote). Only one phase is usually sent to each, with a total of 240v
> possible from the two hots off of one phase (they are actually phase
> inverted from each other). These systems should NEVER be used with
> another phase.
> If the wye was used, as is common in situations where 3-phase motors
> are used (some central air, some industrial, all heavy rigging) or in
> entertainment venues with heavy power needs, each phase, the neutral,
> and the ground are sent to a disconnect where they can either be
> permanently wired into a device or can be left for manual tie-in.
>
> Regardless, all power is measured RMS. 120v AC is actually about 170v
> peak. The RMS measurement between two phases is 207v. The RMS
> between a phase hot and its inverse is 240v. You know you are dealing
> with one phase if you get 0v between hots, or 240v between hots. When
> you get 207v between hots, then they are two different phases. I hope
> this helps.
>
> On 2 Sep 2005 22:08:41 -0700, "saji" <(E-Mail Removed)> wrote:
>
>>I have a doubt in electrical engineering.This is regarding 3 phase.How
>>can i measure from which phase power is coming in a 3 phase connection
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