Re: Straight from th pole

To: tesla-at-pupman-dot-com
Subject: Re: Straight from th pole
From: "David E. Sharpe" <sccr4us-at-erols-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 30 Dec 1999 19:34:21 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Tesla List wrote:
> 
> Original Poster: Jim DeLillo <jimdel-at-bellatlantic-dot-net>
> 
> Is it possible to request HV service directly from the utility company
> rather than get a pole pig?
> 
SNIPP-->>>

Jim

The smallest HV power feeder in this part of the country (Virginia, USA)
is 34.5kV (20kV L-G).  The local power utility has a easement on my
property, and I watched the installation.  The UG feeder is #6 Xlink
PE shielded for direct burial.  60A at 20kV would be approximately
1.2 Megawatts (or MVA) single phase.  Controlling this much power would
require a real switch yard.  I have worked on high power stuff before
(motors to 1,500HP, Power Inverters to 400kVA) and this gets me VERY
nervous.

Real equipment with minimum insulation levels to at least 100kV, plus
lightning protection, plus short circuit protection (short circuit on
even an  underground feeder line like this would be in the many of kA).
Plus the fact I've seen a 34.5kV 3 ph feeder under a fault condition arc
the height of a telephone pole (from road to line level). In short, this
is where real professionals work.  This is NOT the place for Tim Allen
"MORE POWER" engineering.

The first company I worked had 2 dedicated 34.5kV 400A feeders (20MVA
actual load, 65MVA connected).  There is some minimum load requirement
perhaps in the 2-5MVA range as a guess for direct HV feed, but then
everything from the HV connection to the load is the CUSTOMER's
responsbility.  Costs would be significant (unless one had won the
lottery); the company's electric bill previously mentioned was about
$250,000 US per month in 1975 dollars.  I would seriously doubt that a
local Power Utility would risk taking a significant block of customers
or their infrastructure down because of a fault at a substandard
facility.  OBTW, utilities require electrical inspection approval
by local building inspectors, and most would also require certified
drawings stamped by a PE that the electrical installation met applicable
standards (NEC, NESC, IEEE, OSHA, etc.), and that proper
pre-commissioning tests (Hipot, overcurrent protection testing) had been
performed before power would be installed in a HV installation of this
magnitude.  At these power levels, you're in the realm of PUBLIC SAFETY
like it or not; which will add geometrically to the red tape syndrome.

Regards

DAVE SHARPE, TCBOR
Chesterfield, VA. USA