The shield wires above the power conductors on high voltage lines can be
insulated from the pole or be broken up with a small insulator to reduce
circulating currents induced in them from the magnetic and electric fields
from the power conductors. Small insulators are used so they don't prevent
the shield wires from doing their lightning protection job, the small
insulators flashover very quickly so can be ignored when doing lightning
protection design. Reducing the circulating currents helps reduce losses in
the line and can help reduce imbalance between the phases.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of qrv@kd4e.com
Sent: Sunday, April 09, 2017 17:43
To: RFI List
Cc: n4jhy@yahoo.com
Subject: [RFI] Lightning Grounds with Insulators in SC?
Just saw this posted to the swap.qth.com list ...
"Running along the South Carolina coast are two 3 phase 115 kv feeders that
power all coastal towns for about 45 miles. Georgetown, SC to Myrtle Beach."
"About a year ago I noticed that one of the two lightning safety grounds,
both at the top of each pole, now has some sort of insulators on it."
https://swap.qth.com/view_ad.php?counter=1321021
"While driving on a cross road, that goes under this power line, I noticed
this arrangement on one of the poles."
"Does anyone know what this is all about?"
"Thanks, Bruce N4JHY"
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