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Re: pole pig chart (fwd)



---------- Forwarded message ----------
Date: Sun, 26 Apr 1998 14:51:24 -0700
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: pole pig chart (fwd)

> 
> ---------- Forwarded message ----------
> Date: Sat, 25 Apr 1998 17:57:47 -0700
> From: djQuecke <djQuecke-at-worldnet.att-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: pole pig chart (fwd)
> 
> I'm fairly new to high voltage stuff but I think that even though it may
not
> "sound right", I think your pretty close to the answer (with a couple of
> small changes to your column headers and the correct formula).  I believe
I
> just really learned what a kVA is for the first time today while doing
some
> research on my coil project.  I quote:
> 
> "CORRECTED KVA is determined by dividing the volt*amps (watts)
> output of the ..... xfrmr by 1000"
> 
> "Equation courtesy of Richard Quick"
> 
> Included in the Tesla Mirror Archive, Math.txt.
> 
> It appears kVA just another unit for stating wattage that is easier to
use
> at high voltages.  This also means though that a relationship can be
charted
> similar to yours, based upon Ohm's and Watt's Laws, which I don't believe
> change, regardless of the voltage in question.
> 

VA and Watts are only the same for resistive loads. For a load with a
reactive component (i.e. an inductor or capacitor), VA will be greater than
Watts. Watts measures actual energy flow. VA is just volts times amps.
Ideal inductors and capacitors draw current, but are lossless, and consume
no power (i.e. Zero Watts), but since the Amps is non zero, the VA is
non-zero.

Apparent Power (VA) = sqrt ( Actual power^2 + Reactive Power^2)

more at: http://home.earthlink-dot-net/~jimlux/hv/pfc.htm

>  Rather 14.4kV is a normal input voltage with a normal output of
> 120/208 or perhaps 240/408 on a commercial site

A typical residential single phase transfomer would be 240 Volts with a
centertap fed as the neutral. The neutral is grounded at the service
entrance. This gives you 120 V Line to neutral (or ground) and 240 V Line
to Line for higher power loads (e.g. electric stoves, heaters, dryers, and
airconditioners (and Tesla Coils)).

The 120/208 voltage configuration is for a three phase Y connection, 120 V
Line to neutral, 208 V Line to Line. This is popular in office buildings,
where most of the loads are 120V. In an industrial environment, you would
more likely see 240 Delta connected or 480 Delta Connected, with no 120 or
neutral available, except by transforming down from the 240 or 480.   You
might also see 277/480 in three phase, also a Y connection, with the
neutral formed by a "neutral forming" transformer (also called a zig zag
transformer, from the winding interconnection). They use the 277 volts for
lighting, and the 480 to run all the motor loads.

At my shop, we have two completely separate services: 1) a single phase
240/120 Volt service for convenience outlets and lighting; and 2) a three
phase 240V delta service (no neutral) for running motors, and other high
power loads.