Re: HVDC Power Re: Water sparks (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 12 Aug 2003 10:19:46 -0600
From: Gomez <gomez@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: HVDC Power Re: Water sparks (fwd)

On Tuesday, August 12, 2003, at 08:16  AM, High Voltage list wrote:

> Original poster: Steven Roys <sroys@xxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 11 Aug 2003 16:16:55 -0400
> From: davep <davep@xxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: HVDC Power Re: Water sparks (fwd)
>
>
>>> From: davep <davep@xxxxxxxx>
>>> 	I guess it depends on the definition of 'pure'.
>>> 	Where PURE (technical definition) water is
>>> 	used or insulators (eg the 1 MV DC Line
>>> 	that (helps) power my neighborhood...) it means
>>> 	99.9999 (++) % pure.
>
>> Whoa!  What?  You have a DC line in your neighborhood?
>
> 	They all have to be somewhere.  8)>>
>
>> You have a 1MV line near your neighborhood??
>
> 	about 10 mi away, depends on the definition of 'near'.
> 	One end 'here' (outside Boston, MA, USA,
> 	'tother in Quebec, Canada.)

Ah yes, that's one of the big ones.

>> I thought such things were only used for long-haul major
>
>> network balancing tasks.
>
> 	...or for exporting bulk power.  It WILL
> 	work both ways, but doesn't, i think, get
> 	used that way.

Strange, I thought the US was a bigger importer than exporter.
There's a dramatic set of graphs in the September Wired on this.
Canada exports electricity to USA.

>> The highest voltage lines in North America are supposedly
>
>> five inter-network load balancing lines,
>> just air-insulated towers, which run at 750kV / 60Hz.
> 	This is +/- 500KVDC.
>
>
>> As for water insulation, since it so easily ionizes after a
>
>> voltage
>
> 	Its what they use.
>   	(It was an IEEE Tour...)
>
>> has been placed across it for a short time,
>
> 	Doesn't seem to bother its use.  Its used to
> 	'cool' the inverter stacks (LOTS AND LOTS)
> 	of solid state devices (i forget which....)
> 	stacked in series.

Aha, yes, I was thinking of transmission lines.

> Top end is at + (bottom -)
> 	500KVDC, at 100 A (if i recall....).
> 	Line and etc are set up to allow temporary
> 	operation at 1MV to ground, in case of need.
> 	Thus (since its the inverter) there is a pulse
> 	component, but lotsa DC.  Like most any
> 	insulator, if 'enough, plus margin' be used
> 	its OK...

In those cases, they move the water through fairly quickly and
constantly run it over filters, deionizing/demineralizing beds, etc.

>> I was under the impression it was only used for pulse
>
>> work.  I have never heard of high voltage transmission
>
>> lines being insulated with water.
>
> 	The _lines_, being outside are air insulated.
> 	The indoor bits, notably the inverter stacks,
> 	are water...  Very Pure Water...

Quite.

>> I am very, very skeptical that this is being done,
>
> 	It's being done.

Just not what I was thinking.  :)

> 	8)>>
> 	ASEA (as was) engineered it, if i recall.

ASEA / ABB are the big static inverter boys as far as I can tell.