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Re: [TCML] My first tesla coil
Yes. AC induction can be deadly for linemen working on otherwise
disconnected lines that parallel energized lines. This is especially
true with high voltage transmission lines. Unenergized lines are first
always grounded to prevent accidental electrocution from otherwise
seemingly "dead" lines:
The induction field can also be artistically "mapped" near transmission
If you park a vehicle directly under one phase of a HV transmission
line, you can sometimes feel a distinct "nip" when barely touching the
vehicle. Induction can become a significant problem with metal fences or
large metal buildings that parallel transmission lines.
HVDC transmission lines can also induce annoying voltages onto nearby
objects via electrostatic induction and ionic currents (single-polarity
corona charging). For example, during tests by the Electric Power
Research Institute (EPRI), voltages of 10-20 kV (and sometimes
considerably higher) were commonly induced on vehicles parked 30 meters
away from a 600 kV negative monopolar line. Although not as prevalent as
AC transmission lines, DC lines are a critical part of our power grid.
See for example the +/-500 kV Pacific DC Intertie:
Dex Dexter wrote:
Hey,thanks Bert!That's veeery interesting.Do you know if that corona
charging effect happens also in the vicinity of HV power lines?
--- bert.hickman@xxxxxxxxxx wrote:
From: Bert Hickman <bert.hickman@xxxxxxxxxx> To: Tesla Coil Mailing
List <tesla@xxxxxxxxxx> Cc: Subject: Re: [TCML] My first tesla coil
Date: Sun, 06 Sep 2009 14:42:57 -0500
In addition to electromagnetic induction, there is also the
phenomenon of electrostatic induction:
Space charges (injected by nearby streamers and leaders) will also
induce potentials on nearby isolated conductive objects by direct
charge deposition via "corona charging". As a result, a sphere,
placed outside the range of visible discharges from a Tesla Coil,
will rapidly charge a HV capacitor (where the other end of the
capacitor is connected to ground). This is markedly different than
the RF capacitive coupling that also occurs between secondary/toroid
and nearby conductive objects.
Corona charging or corona rectification has been used to make low
current HV rectifiers and is currently used in electrostatic
copier/printing and polymer pretreatment for printing.
Dex Dexter wrote:
Well,if they remain charged after turning off the coils (for a
longer time) that can't be induction.
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