Whole house "battery" wiring/power...


wrote:

----- The sensitivity of humans and other mammals, with regard to frequency happens to peak in the 50-60Hz range. Edison took advantage of this and Tesla countered with high frequency, high voltage discharges, saying, in effect, "this is AC, perfectly safe" Both lied (whether they knew it or not and the not was shown much later) with profit as a motive. Other hazards such as arcing at switches or poor contacts, worse with DC, were ignored.
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 13 Oct 2009 19:51:24 -0700, Don Kelly wrote:

I recall the breakers at one site I was working at fed compressed air through the breaker upon opening, just to extinguish any arc that may have formed (that was a 400V DC setup) - I think that's typical on higher power DC stuff. The breakers were about the size of a lunchbox.
cheers
Jules
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jules wrote:

Hi voltage AC breakers still do use compressed air in some. The 'blast' is aimed between the arcing contacts to literally blow out the arc.
Lower voltage DC (up to 350VDC) that we used on submarines just used blow-out coils to create a magnetic field that 'pushed' the arc-conducting gases up into chutes lined with alternating metal and insulating plates that would cool and stretch the arc.
But I've seen enough stuff that I know I haven't seen everything :-)
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 14 Oct 2009 17:30:15 -0400, daestrom wrote:

Interesting - not seen those before. 'ours' were WWII-vintage, and there was compressed air in the same room as part of the air-start system for the generators, so I suppose it was no big deal to route it to the electrical switchboard too.

:-) I'm sure there were all sorts of ways and means of extinguishing arcs, though - some of which may have worked better than others!
It'd be interesting to know what larger power stations etc. did, too. Had some friends in NZ with a smaller plant (2,500 kVA) but I've not talked to them in quite a while, and I don't recall anything obviously resembling breakers on the site, although I assume they were there somewhere!
cheers
Jules
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jules wrote:

Another variant that I worked with was spring to open and the bottom side of the mechanism pushed a plunger in a cylinder to make a 'gush' of air that was directed from below the contacts, up between them into the arc chute. Of course it was just a short burst of air, but the idea was to blow the hot gases up into the chute where the plates would separate and cool them.
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

------------- High voltage air blast breakers for AC have been around since the late 40's. They were/are modular with series sections and could then be extended to higher voltage by adding sections. The contact opening in a section was about 1 inch and 600psi air was driven through the arc, extending it towards a vent but not actually interrupting the arc until the arc naturally collapsed at current zero- then the arc products were blown out and the gap filled with good dielectric (high pressure air). A two gap section was good for 72KV and 2 of these in series for 161KV. Two gap sections could be linked together and put on longer columns at higher voltages there was a loud bang when they operated. The advantage of these breakers from Europe was that they were smaller, lighter, faster and cheaper than the oil breakers in use up to that time in North America. There was a bit of a war of words going on in IEEE PAS regarding the relative merits of bulk oil breakers and air blast breakers and air breakers won out. Even the old circuit breakers at, say 15KV up whether oil or air blast operated on the principle of removing arc products, replacing them with good dielectric, when the current went through zero. This principle is used for HV minimum oil and SF6 breakers (blast of oil or SF6 through the gap).

------------ At lower AC voltages- say 5-15KV such breakers are often used- You could take one of these and derate it to about 400-500VDC and it would likely work. That current zero every half cycle makes a big difference.

Me too
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

We need big, engine block sized solid state switches. :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
windcrest wrote:
message

Have you had any experience with high frequency AC power systems? I've come across 400hz AC power in some old computer installations and seen a lot of military surplus aircraft power equipment that used 400hz AC power. My assumption has always been that higher the frequency, the smaller the mass of the transformers not only making equipment smaller but lighter.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Very common (standard?) in aircraft.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

In addition to smaller generator/motor and transformer sizes and weights for a given power, the 400Hz machines can be driven at higher speeds eliminating some or all gearing in high rpm aircraft usage (up to 24000 rpm at 400 Hz vs up to 3600 rpm at 60 Hz. ). For aircraft the distances involved are short so that inductance and capacitance are not a problem .
In general, for land based applications the advantages are outweighed by the disadvantages because of the distances involved.
Switching power supplies were not an option in those days.
--
Don Kelly
snipped-for-privacy@shawcross.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, silly. 400Hz is still the standard for aviation.
Use some sense. Why would they *downgrade* to a heavier system with zero co-compatibility?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Filter capacitors and inductors too. It's not uncommon for switching power supplies to be above 1MHz, also to keep the size of components (and costs) small.
...and transformers get *very* big at DC.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 9 Oct 2009 14:33:42 -0700 (PDT), " snipped-for-privacy@gmail.com"

I want a citation that switchers are commonly running at and above 1MHz.
NONE of ours did.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Archimedes' Lever wrote:

I've never seen a switching power supply that ran at 1Mhz.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 13:30:57 -0500, The Daring Dufas

They're really not uncommon today. LTC has a pile of 'em. Hint: ignore DimBulb. You won't learn anything from him. He's AlwaysWrong and dumber than even you are.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
krw wrote:

My statement still stands. I've never seen a switching regulator that ran at 1Mhz. Just because the chip is capable of 1Mhz does not mean that that is the switching speed of the regulator. Most of the design engineers I'm familiar with tend to be conservative. Your opinion is not that important. Opinions are like tailpipes, everyone has one, except for those like you who have theirs transposed with their induction system. FLNF
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 18:04:29 -0500, The Daring Dufas

Idiot. That is the switching speed of the regulator.

They don't have a choice, darling dufus. The regulator switches at 2.25MHz, whether they're conservative or commie.

My opinion may not be important to you, but my facts are at least facts. I do this stuff for a living, you? Clean septic systems? ...with a mop?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
krw wrote:

Oh my God, a professional actinic sphincter. FLNF
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 10 Oct 2009 19:52:36 -0500, The Daring Dufas

What you have your mop out? Looking for work?
I was wrong, you and DimBulb are made for each other.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
krw wrote:

Kid, I can guarantee that if you and I entered the same industrial site, I would be able to handle more of the systems than you could. Don't get too arrogant, unless you're Superman. FLNF
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.