Why 110V grid runs in 60Hz?

[Jaguarjoe]

I believe you can get 3 phase power by tapping into 2 of your neighbor's power panels. They must be sequential.

 

[ChrisP58]

I believe you can get 3 phase power by tapping into 2 of your neighbor's power panels. They must be sequential.

A single transformer will usually feed half a dozen or more homes, so you might need to go a ways to get the 2nd phase. And a few houses in the other direction to get the third phase.

 

[jpanhalt]

My neighborhood is 13000+ volt, two wire going to transformers for every 4 to 6 homes. There is no way to get three phase from that.

John

 

[crutschow]

I believe you can get 3 phase power by tapping into 2 of your neighbor's power panels. They must be sequential.

I think most residential transformers are single-phase with two wire inputs from the HV line. It would have to be a 3-phase transformer with 3 wire inputs to generate a 3-phase output.

 

[crutschow]

It's even more strange - America commonly used aluminium wiring rather than copper at one time now that is nasty!.

Yes, they did use aluminum wiring for a short period of time in homes here, but it was soon abandoned because of the problems. One guy at work had an older home with Al wiring and he said there was a real danger that an outlet could overheat and start a fire. The problem was the Al would develop an insulting oxide which caused a high resistance at the connection to the wall sockets. A large load connected to the socket could then raise the temperature high enough to start the wire insulation burning. The proper way to minimize that was to using special protective grease over all the connections but if that wasn't done properly, you were in trouble.

 

[crutschow]

The power grid and all those nice things were developped in the early stages of technology and communication. Pal is not better (for the most part) because it is newer than NTSC, but because of the 60 Hz. Colour TV uses interleaving technology. The higher the mains frequency, the more lines (sharper pix) you get.
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It's not just the vertical scan rate, which was originally equal to the main's frequency, that determines the resolution, but the ratio of the horizontal scan rate to the vertical scan rate. For a given horizontal rate a 50Hz vertical rate would actually give a higher resolution than a 60Hz scan since it would have more horizontal lines per picture.

 

[Mike odom]

Pal contains a colourbust signal that calibrates the colour line by line, ntsc doesnt do that and on old tellys the colour went squiffy to the right of the screen and had to be adjusted every so often.

NTSC certainly contains a line by line colorburst sync pulse, 8 pulses minimum (3.58MHz). I think the problem with earlier NTSC systems were in the comb filters, or maybe the sync osc not as sharp as it should've been, since the color info had to be interlaced into the brightness info so a bw tv would still work. But that's the problem with PIONEERING a system, those who copy have a chance to improve upon... and PAL stands for pictures at last... the Yanks figured out how to do it, so let's not only copy, but improve upon it while we're at it

 

[Mike odom]

Yes, they did use aluminum wiring for a short period of time in homes here, but it was soon abandoned because of the problems. One guy at work had an older home with Al wiring and he said there was a real danger that an outlet could overheat and start a fire. The problem was the Al would develop an insulting oxide which caused a high resistance at the connection to the wall sockets. A large load connected to the socket could then raise the temperature high enough to start the wire insulation burning. The proper way to minimize that was to using special protective grease over all the connections but if that wasn't done properly, you were in trouble.

Another problem with aluminum wiring was it was a softer metal, and the connections would loosen up over time, and had to be periodically tightened, or the loose connections could cause blackout, or high resistance connections leading to overheating. One house I lived at in the 80's kept losing power on one leg, but it would come back if you turned the stove on. The reason is the neutral at the incoming connection would loosen and disconnect, and the system would float. Turning on the stove which is 220 would reset the voltages. That took some head scratching to find

 

[Nigel Goodwin]

Pal is not better (for the most part) because it is newer than NTSC, but because of the 60 Hz. Colour TV uses interleaving technology. The higher the mains frequency, the more lines (sharper pix) you get.

Sorry, but you are completely incorrect

PAL has MORE lines (625 as against 525) than NTSC, it's not a function of mains of frame frequency - so as well as a superior colour system it has higher resolution as well. This is why HD was important in the USA, because it's a much greater improvement than it is for PAL.

 

[crutschow]

Sorry, but you are completely incorrect

PAL has MORE lines (625 as against 525) than NTSC, it's not a function of mains of frame frequency - so as well as a superior colour system it has higher resolution as well. This is why HD was important in the USA, because it's a much greater improvement than it is for PAL.

But interestingly, the ratio of 625 to 525 is very close to the ratio of power line frequencies (and thus vertical scan rates) between Europe and the U.S. so the horizontal line frequencies are very similar.

 

[kinarfi]

Yes, they did use aluminum wiring for a short period of time in homes here, but it was soon abandoned because of the problems. One guy at work had an older home with Al wiring and he said there was a real danger that an outlet could overheat and start a fire. The problem was the Al would develop an insulting oxide which caused a high resistance at the connection to the wall sockets. A large load connected to the socket could then raise the temperature high enough to start the wire insulation burning. The proper way to minimize that was to using special protective grease over all the connections but if that wasn't done properly, you were in trouble.

It wasn't so much the oxide as it is the properties of aluminum that it will not hold compression regardless of how tight you tightened the terminal , so when the wire heats and expands, it "squashes", then when it cools, it is no longer tight, and then it can oxide and create heat which creates more "squish" and on and on. The cure was to pig tail a piece of copper wire onto the end of the aluminum wire with either a wire nut or butt spice with the use of Pentrox, One of the a fore mentioned greases that contain zinc. The zinc would penetrate the oxide and the grease would keep the oxygen away for a better connection.
Another problem that comes with 220/110 system is the center tap ground/nuetral, if the house looses it's nuetral and the load on each side of nuetral is not balanced, the side with the lesser load will over voltage and possibly burn out the items on that side. I've seen that.
My 2¢ worth and pretty much what Mike odom said, but I posted before I read his post.

 

[dr pepper]

Pal is pretty much a subject for conjecture now in the uk, its vanishing quick, eveyones gone dvb.
My local transmitter was 500kw when it was analogue, now its only 10kw, and we can still get a good picture.

 

[throbscottle]

... the Al would develop an insulting oxide...

Sniglet

 

[jrz126]

I'm confused. Does this mean if you connect a live wire from one socket in your house, and a live wire to another socket in your house (or maybe your neighbours house), you get 240V?

Reminds me of when i was working on a SCR/Triac based power supply for my Tesla coil. I was in the lab at school testing it (just the powersupply, Tesla coil was too big to bring in). I setup the zero crossing/control circuit on one bench and the SCR power circuit on another with a fiber optic cable between them. Turned it on and I couldn't get the firing angle to 0*. After troubleshooting for a few hours, I finally realized that each bench was on a different phase, so the zero crossing on one bench was 60* on the other.

 

[Nigel Goodwin]

Pal is pretty much a subject for conjecture now in the uk, its vanishing quick, eveyones gone dvb.
My local transmitter was 500kw when it was analogue, now its only 10kw, and we can still get a good picture.

This is a VERY common cause of confusion - the transmitter power hasn't been reduced from 500KW to 10KW at all - as the signals are completely different, their method of measurement is completely different as well. While I'm not clear on the exact comparisons, it seems likely that the transmitters final digital power is pretty similar to the original analogue one.

Incidentally, the analogue rating was a peak one, specifically the power on peak whites.

It's all down to how you can actually measure, as analogue changes from moment to moment you can only measure it at a specific and accurately known instant (in this case the peak white).

 

[crutschow]

I believe NTSC used maximum transistor power for the black level. That is because picture noise is more noticeable in the dark areas of the picture compared the the light areas, and if there is a fixed level of noise, there will be a higher signal-to-noise ratio and thus less noticeable noise, at the peak (black level) of the transmitted power.

 

[Mike odom]

I believe NTSC used maximum transistor power for the black level. That is because picture noise is more noticeable in the dark areas of the picture compared the the light areas, and if there is a fixed level of noise, there will be a higher signal-to-noise ratio and thus less noticeable noise, at the peak (black level) of the transmitted power.

that may be true, I don't know, but I thought TV transmission is an FM modulated signal, with the audio being AM modulated. That means you'd have a fairly constant power, with the peaks at the edges of the modulation of the signal.
I do know that on the video signal, the sync pulse is lower than black, and white is at the top and black is at the bottom.

 

[Nigel Goodwin]

that may be true, I don't know, but I thought TV transmission is an FM modulated signal, with the audio being AM modulated. That means you'd have a fairly constant power, with the peaks at the edges of the modulation of the signal.

You think wrongly

Analogue (terrestrial) TV was AM modulated, with the sound carried as FM on an 'inter-carrier' frequency (6MHz in the UK, 5.5MHz in the rest of Europe).

Analogue satellite was FM modulated, which is why you got 'sparklies' and 'darklies'

 

[arvinfx]

Guys, It is about Hz only . Why when they changed 110 to 220 they reduced the frequency to 50Hz? Why 220V 60Hz not?

 

[dr pepper]

Dont some countries run on 220 at 60hz?.

I never really understood vestigial modulation, I was looking at the squirrels in the college playing field when that was the subject.