As an electrical Engineer with my primary background being power systems, ie generation, protection, transmission and conversion, I think I should correct you a bit.
For an electric power transmission line, this "loop" is the wires on the left and right sides of the power-line crossbar (OK, not all lines look like that, but the principle is the same). You can trace an imaginary line down one side of the power line and back on the other, enclosing a loop 12 feet wide and many miles long, with enormous area. This is one reason power lines are a bad idea for carrying RF signals; they make a GREAT antenna.
Not really true, most power transmission is done in 3 phases, with all 3 phases summing to a return path on the Neutral wire (which you don't need if everything is balanced, which transmission lines are close to so they omit it, using the ground for a neutral). Which you could really look at it as three return paths in the ground and three primary all at once, I suppose, but not technically correct. Now residential distribution might be single phase, but this is nothing compared to the amount of 3 phase out their right now.
Interesting note: Cross-country power lines ARE in fact twisted pairs, to prevent another interference type. At every Nth tower, you'll see the lines cross over so the left-hand line goes to the right. This results in loops of a half-mile length or so; useless for shielding from RF, but VERY important for protecting the grid from geomagnetic storms, where the Earth's magnetic field is pushed around by solar wind. Making the net loop area zero prevents the transmission line from acting as a giant DC generator and blowing out the switchgear, causing major blackouts (this happened in Canada in the 1970s, IIRC).
What you a describing is called transposition, and it has nothing to do with interference from magnetic storms. A single power line can be seen as a long resistor and inductor in series with a shunt capacitor to ground. Three lines can be seen as the same thing, however with a very small magnetic coupling between lines, often model as a transformer, and a capacitor between lines. Now there are a number of ways to calculate these values, and they are all based on the physical geometry of the line. So if A phase is next to B phase is next to C phase for 300 miles, then your get an unbalance because more A phase is couple into B than into C. When all of these calculations were made by hand, this made for some seriously heinous matrices, which are critical for stability calculations. To solve this problem you twist the wires, sort of. There are a number of different techniques to do this, IE just twisting 2 wires, and leaving one alone, doing all three. These towers are called crossover towers, and their use has been decreasing, due to the fact that at these locations there a higher percentage of transient faults occur (lightning strikes, squirrels getting zapped), which is a pretty big deal to people who make their money 'wheeling' power (transporting power through their systems). As well computers are used pretty extensively for modeling power lines (EMTDC or ATP) and they can deal with 1000x1000 matrix reduction way better than I can.
BTW solar storms did affect the Canadian outage, this is referred to as Geomagnetically Induced Currents (GIC). But it's not DC, it can't be it has to be AC to be seen by the relays that this effects. Basically it causes large ground currents to flow in and out of the system at unpredictable locations and magnitudes. When this happens, a lot of protective devices see a large ground current and assume they have a single line to ground fault and open up the breaker. This is really no big problem, open a breaker at full load is nothing compared to opening with a bolted 3 phase to ground fault right at the terminals of the breaker. If you go here he comments on "When power is restored, all thermostatically controlled electric loads com
Not exactly true, they have a proprietary IP stack, to provide the determinism. 802.3 does not provide for this kind of service, much to the the chagrin of most realtime processes
If Moore states a fact in his 'documentary' that happens to be supported else where, we cant use it as a fact now? Nowhere did he reference Moore or the Da Vinci Code. Way to be obtuse.
I'm not really clear on the physics behind nuclear reactions, I was trying to pick up on the full workings on the device while talking to someone much smarter than I!;->
To operate a nuclear reactor you only actually use something like 3% of the available isotopes as fuel before the efficiency of the plant drops below what is feasible to operate.
Dual Processors != SMP, SMP is just one method. The AMD K5 used to do OpenPIC(I cant speak for K6's), which incidentaly is what the quad proc G3 computer running linux uses for the multiprocessor implimintation. saw it on Slashdo recently, but I'm to lazy to find it. ---------------------------------
ESL's Electrostatic Loudspeakers. Been around for a while, and can perfeclty reproduce a square wave. You cant see through them though. ---------------------------------
1) K6-3 are not SMP they are OpenPIC I belive(K6-2 were)....but no openPIC boards exist. 2) K7's are not Super7, they are SlotA and have an entierly different chipset. ---------------------------------
some time ago I saw a product that gives you access to PC Cards through IDE. I thought so atleast, it could be just another pipe dream.;-> ---------------------------------
Hmmm that assumes no error corection of anykind. adding error correcting and handshaking will increase these number. I would also hope that we will finaly move away from 30 fps to somthing much better say 60? ---------------------------------
NT is much better than 9x....but "much better" is all relative.;-> I cant wait untill I upgrade my machine and move completley to Linux. I was Planning on and AMD K7 when they come out, a TNT2 card and about 128 megs of ram, any thoughts/suggestions? --------------------------- ------
About 6 months ago I got this idea and started to do some serious research on the internet and I have amassed a fem book marks of sites with some more informative content. I think the most informative site is Water cooled CPU's . Basicaly he addresses most of the points brought up in this discussion. In brief; Alcohol sucks, use Vasaline to stop condensation on the pins, and water works really well.
CAn you say flaming motherboard?? Mother boards run on +12v, -12v, and 5v's dc if you want to get picky. The POWER SUPPLY can take either 110v or 220v ac, but either way they still output the same volts in dc. The processes is just more efficent(read: less heat from the power supply) if you use 220v. ---------------------------------
Slashdot Mirror
As an electrical Engineer with my primary background being power systems, ie generation, protection, transmission and conversion, I think I should correct you a bit.
For an electric power transmission line, this "loop" is the wires on the left and right sides of the power-line crossbar (OK, not all lines look like that, but the principle is the same). You can trace an imaginary line down one side of the power line and back on the other, enclosing a loop 12 feet wide and many miles long, with enormous area. This is one reason power lines are a bad idea for carrying RF signals; they make a GREAT antenna.
Not really true, most power transmission is done in 3 phases, with all 3 phases summing to a return path on the Neutral wire (which you don't need if everything is balanced, which transmission lines are close to so they omit it, using the ground for a neutral). Which you could really look at it as three return paths in the ground and three primary all at once, I suppose, but not technically correct. Now residential distribution might be single phase, but this is nothing compared to the amount of 3 phase out their right now.
Interesting note: Cross-country power lines ARE in fact twisted pairs, to prevent another interference type. At every Nth tower, you'll see the lines cross over so the left-hand line goes to the right. This results in loops of a half-mile length or so; useless for shielding from RF, but VERY important for protecting the grid from geomagnetic storms, where the Earth's magnetic field is pushed around by solar wind. Making the net loop area zero prevents the transmission line from acting as a giant DC generator and blowing out the switchgear, causing major blackouts (this happened in Canada in the 1970s, IIRC).
What you a describing is called transposition, and it has nothing to do with interference from magnetic storms. A single power line can be seen as a long resistor and inductor in series with a shunt capacitor to ground. Three lines can be seen as the same thing, however with a very small magnetic coupling between lines, often model as a transformer, and a capacitor between lines. Now there are a number of ways to calculate these values, and they are all based on the physical geometry of the line. So if A phase is next to B phase is next to C phase for 300 miles, then your get an unbalance because more A phase is couple into B than into C. When all of these calculations were made by hand, this made for some seriously heinous matrices, which are critical for stability calculations. To solve this problem you twist the wires, sort of. There are a number of different techniques to do this, IE just twisting 2 wires, and leaving one alone, doing all three. These towers are called crossover towers, and their use has been decreasing, due to the fact that at these locations there a higher percentage of transient faults occur (lightning strikes, squirrels getting zapped), which is a pretty big deal to people who make their money 'wheeling' power (transporting power through their systems). As well computers are used pretty extensively for modeling power lines (EMTDC or ATP) and they can deal with 1000x1000 matrix reduction way better than I can.
BTW solar storms did affect the Canadian outage, this is referred to as Geomagnetically Induced Currents (GIC). But it's not DC, it can't be it has to be AC to be seen by the relays that this effects. Basically it causes large ground currents to flow in and out of the system at unpredictable locations and magnitudes. When this happens, a lot of protective devices see a large ground current and assume they have a single line to ground fault and open up the breaker. This is really no big problem, open a breaker at full load is nothing compared to opening with a bolted 3 phase to ground fault right at the terminals of the breaker. If you go here he comments on "When power is restored, all thermostatically controlled electric loads com
Not exactly true, they have a proprietary IP stack, to provide the determinism. 802.3 does not provide for this kind of service, much to the the chagrin of most realtime processes
If Moore states a fact in his 'documentary' that happens to be supported else where, we cant use it as a fact now? Nowhere did he reference Moore or the Da Vinci Code. Way to be obtuse.
I'm not really clear on the physics behind nuclear reactions, I was trying to pick up on the full workings on the device while talking to someone much smarter than I! ;->
All of them.
To operate a nuclear reactor you only actually use something like 3% of the available isotopes as fuel before the efficiency of the plant drops below what is feasible to operate.
AK is Alaska, ass, not ARkansa
Dual Processors != SMP, SMP is just one method. The AMD K5 used to do OpenPIC(I cant speak for K6's), which incidentaly is what the quad proc G3 computer running linux uses for the multiprocessor implimintation. saw it on Slashdo recently, but I'm to lazy to find it.
---------------------------------
ESL's Electrostatic Loudspeakers. Been around for a while, and can perfeclty reproduce a square wave. You cant see through them though.
---------------------------------
1) K6-3 are not SMP they are OpenPIC I belive(K6-2 were)....but no openPIC boards exist.
2) K7's are not Super7, they are SlotA and have an entierly different chipset.
---------------------------------
some time ago I saw a product that gives you access to PC Cards through IDE. I thought so atleast, it could be just another pipe dream. ;->
---------------------------------
Hmmm that assumes no error corection of anykind. adding error correcting and handshaking will increase these number. I would also hope that we will finaly move away from 30 fps to somthing much better say 60?
---------------------------------
NT is much better than 9x....but "much better" is all relative. ;-> I cant wait untill I upgrade my machine and move completley to Linux. I was Planning on and AMD K7 when they come out, a TNT2 card and about 128 megs of ram, any thoughts/suggestions?- ------
--------------------------
About 6 months ago I got this idea and started to do some serious research on the internet and I have amassed a fem book marks of sites with some more informative content. I think the most informative site is Water cooled CPU's
. Basicaly he addresses most of the points brought up in this discussion. In brief; Alcohol sucks, use Vasaline to stop condensation on the pins, and water works really well.
---------------------------------
CAn you say flaming motherboard?? Mother boards run on +12v, -12v, and 5v's dc if you want to get picky. The POWER SUPPLY can take either 110v or 220v ac, but either way they still output the same volts in dc. The processes is just more efficent(read: less heat from the power supply) if you use 220v.
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