Hero999 said:Don't count on being thrown free, AC can make your mussels freeze up too.
Maybe in the 1980s, but today quasi resonant switch mode power supplies can be as efficient as any distribution transformer and there are no skin effect losses in the distribution system.
The US have 240V and 120V sockets and they don't have a problem.
We have 110V, 230V and 400V sockets at work and we've never had a problem. They are colour coded and keyed to prevent mistakes from being made.
Don't get me wrong, I'm not suggesting we should switch over to DC, I can just see the benifits of a DC system, especially for smaller appliances.
Pommie said:While we're on the subject, which is better, earthing the neutral or not? (don't know what the US call it - the one that isn't hot)
Pommie said:I can't give you a technical reason but back in the UK I had a friend that built lights and he tried to introduce a 48V system for compact lighting. This was for two reasons, below 50V was unregulated and the electronic ballasts were much cheaper and I assume simpler at that voltage.
Leftyretro said:Could the higher 'skin effect' (higher line resistance) of using 400hz on very long power lines Vs 50/60 hz be a factor in selecting the lower frequency for power distrubution?
Lefty
dknguyen said:There is a type of induction motor that can be wired up as a transformer. At equal frequencies on primary and secondary, it appears as a transformer. If one is slightly off the induction motor will slowly spin and allows for two different frequencied grids to be connected together. I think it's used somewhere between the Canadian and American electrical grids.
Nigel Goodwin said:Don't even go there!
Like most things, 'better' is a relative term.
Nigel Goodwin said:I would disagree with 'safer', most of the electronic and electrical trade consider AC far safer than DC (as do I). An AC shock will usually throw you clear, a DC shock tends to freeze you on the wire - and is much more likely to kill you.
I would also disagree with 'feasible distribution', it's far too inefficient, and the original DC premise was based on a small power station on every street corner.
It's also a very bad idea to have multiple mains supply sockets, that's been done, and is long over now (although you still do see it very occasionally) - different mains sockets upstairs and downstairs was never a good idea.
DC mains was also done years back, that was never a good idea either!.
Hero999 said:Don't count on being thrown free, AC can make your mussels freeze up too.
Maybe a return to the old "knob and tube" wiring method?Nigel Goodwin said:I can only imagine he was wanting to use bare metal feed wires?, as is quite common with low voltage lighting.
audioguru said:Don't you guys know how to spell in English???
A mussel is a hard black shell fish.
A muscle moves your arms, legs and other parts.
dknguyen said:There is a type of induction motor that can be wired up as a transformer. At equal frequencies on primary and secondary, it appears as a transformer. If one is slightly off the induction motor will slowly spin and allows for two different frequencied grids to be connected together. I think it's used somewhere between the Canadian and American electrical grids.
quixotron said:Has anyone tried connecting their nutts to a high voltage/power source?
120VDC is unlikely to kill you 120VAC is pretty likely to kill you, 60VDC probably won't even shock you, 60VAC might even kill you.Nigel Goodwin said:Under very rare conditions perhaps, but with DC it's almost certain to freeze you one the wire and kill you! - I'd sooner take the 99% chance of been thrown free, than the 99% chance of death!.
**broken link removed**The first occurred when I was eight years old. My brother was trying to learn about electrical circuits by wiring bells and lights in various circuits and then energizing them with 115 V ac. The circuit was on a large round oak table in our dining room and power came through two long wires from the chandelier above the table and ending in non-insulated alligator clips.
The thing I did not notice was that my brother always put on rubber gloves before picking up the alligator clips. After showing me what fun it was, he cautioned me not to touch anything when he left the room. I immediately picked up the clips to try my hand with the lights and bells. The first shock involuntarily caused a spasm in my hands that would not allow me to let go of the electrodes. 115Vac went from one hand through my arm, upper torso, arm, and out the other hand. Unable to let go and shouting at the top of my lungs, I made two quick involuntary circles of the table and was then thrown deep into the fire place where I was pressed between the back wall and grate -- still unable to let go or even move in my tight fire-place-cage. It was probably less than 15 seconds before my brother responded to my yelling and pulled the wires out of the chandelier, but it seemed to me more like a lifetime.
That's the only valid point you've made so far.I'm sure a multi-KW switchmode power supply, fed from 300 or 4 thousand volts, is going to give similar reliability to a simple transformer!
Why would you need transistors with such a high rating?Where's my databook?, I seem to have missed thouse 500KV 1000A MOSFET's
Apart from safety, the main advantage I can see is that it would mean that you wouldn't have to worry about harmonics or power factor correction when designing a switch mode power supply for something like a PC.Can you?, such as what?
Also, I'm only talking about low voltage supplies, medium voltage will still be AC. Low voltage DC can be derived using a phase shifting transformers and rectifiers, no capacitors or regulators are required. The three phase supply is converted to a 24 phase supply which gives vertually no ripple on the output and the input harmonic currents are very low.and what's the source of the DC going to be?.
Bonding the neutral to earth is normally done for the following reasons:Pommie said:While we're on the subject, which is better, earthing the neutral or not? (don't know what the US call it - the one that isn't hot)
Hero999 said:The idea the AC makes you let go and DC makes you freeze is a complete myth.
It is a myth.Nigel Goodwin said:Certainly not, I personally know of many instances were it has applied. Basing your premise on one single incident hardly makes it a myth.
I wouldn't rely on this, the skin on the back of the hand is normally dry and might have a resistance of >1MOh, a quick tip for anyone who doesn't know?, never touch any exposed metalwork with the palm side of your hand - stroke it with the back of your fingers - if it's live it will feel rough.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?