Washing machine 240, 50Hz - 240, 60 Hz?

Reply to
george_corinne
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hmmm... 4320 RPM and 2160 RPM generators. More power in the same size generator, but the turbines would change, some for the better, some for the worse.
X sub L of the power lines increased by 20%. Charging currents increase by 20%.
Reply to
Matthew Beasley
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Reply to
george_corinne
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| |> There are many aspects of the US/North American system I don't like. |> The 60 Hz is about the only thing I do like about it. I'd rather go |> on up to 72 Hz. |> | | hmmm... 4320 RPM and 2160 RPM generators. More power in the same size | generator, but the turbines would change, some for the better, some for the | worse. | | X sub L of the power lines increased by 20%. Charging currents increase by | 20%.
Oh, well, then let's go to 36 Hz.
Reply to
phil-news-nospam
This has been the subject of many discussions before. Go too low (and this includes 50 Hz AFIC) and the incandescent lamps will flicker because the filaments cool too quickly. Yes, I know it is just a matter of time before all incandescents will be CF lamps and LEDs, but we are not anywhere near that point yet.
Go too high and the inductive reactance of all power lines and transfomers increase (as noted by the previous poster). At 60 Hz, there are many large commercial/industrial two-pole high power generators that operate at 3600 rpm (driven by steam turbines at many nuclear plants, for example). At 72 hz, this would be 4320 rpm and include all the additional stresses that want to make a large flywheel type machine fly apart.
As for increasing the charging current, major cities like New York can't even keep the lights on in Queens during the summer because they have more charging current than they know what to do with. They even have to run over-excited generators with no load to generate negative VARS at times, just to keep the lights on.
Historically, 25 Hz works great for elevators and electric transit. 16 2/3 Hz works for many electric railroads.
Though, you can argue the point that the US 120V. utilization voltage is too low (and I would argue that it still contributes to a safer installation for residences even with GFI's and RCDs).,, I would argue that standardizing the frequency at 60 Hz instead of 50 Hz was something the US and Canada got right around 90-100 years ago.
If you don't like 50 Hz, you can blame Germany as they were Europe's manufactuer of most of the electrical equipment at the beginning of the 20th century.
Beachcomber
Reply to
Beachcomber
| This has been the subject of many discussions before. Go too low (and | this includes 50 Hz AFIC) and the incandescent lamps will flicker | because the filaments cool too quickly. Yes, I know it is just a | matter of time before all incandescents will be CF lamps and LEDs, but | we are not anywhere near that point yet.
"all incandescents will be CF lamps and LEDs" ... ???
That would be a good trick. Be sure to patent it.
| Go too high and the inductive reactance of all power lines and | transfomers increase (as noted by the previous poster). At 60 Hz, | there are many large commercial/industrial two-pole high power | generators that operate at 3600 rpm (driven by steam turbines at many | nuclear plants, for example). At 72 hz, this would be 4320 rpm and | include all the additional stresses that want to make a large flywheel | type machine fly apart.
Note that I am not proposing this as where to change to. It is just what I think would have been a more ideal choice to begin with. All the things we have today that depend on either 50 Hz or 60 Hz would not have been created.
| Historically, 25 Hz works great for elevators and electric transit. | 16 2/3 Hz works for many electric railroads.
I bet that was the case for older designs. The elevators I have seen had a nice gearing system to step the rotary speed from the main drive motor down to the cable drum speed.
| Though, you can argue the point that the US 120V. utilization voltage | is too low (and I would argue that it still contributes to a safer | installation for residences even with GFI's and RCDs).,, I would | argue that standardizing the frequency at 60 Hz instead of 50 Hz was | something the US and Canada got right around 90-100 years ago.
120 volts is safer than 240 volts 60 volts is safer than 120 volts 30 volts is safer than 60 volts The NEC even lets you have exposed conductors at 30 volts.
But at some point the higher fault current also raises the danger.
Compare the danger of 120 volts 60 years ago to 240 volts today. I think that comes out about even. And that's for 240 volts L-N as they have in UK, Australia, Brazil, etc. I propose it would be better to have a L-L system as I believe most electrical shocks and electrocutions are L-G. The US system of 240 volts is really 120 volts L-G (as you know). My suggested system would be 288 volts L-G. Sure, it would have been more dangerous back 100 some years ago when it would have had to be deployed to make it economical to have today. And that risk may well have doomed any such proposal. Sadly, we have a less efficient system today because of historical risks that are way less significant today.
We have technology like GFCI that reduces the risks today. I wish we could have had that decades earlier.
Today we have much higher fault currents due to the demand for more power and the resultant larger transformer capacities. That isn't so much of a concern on long branch circuits with smaller wire. But it's a big concern in some places like inside panels.
I would not at all be bothered by 480 or 600 volts coming into my home on the service entrance and being stepped down by a transformer.
| If you don't like 50 Hz, you can blame Germany as they were Europe's | manufactuer of most of the electrical equipment at the beginning of | the 20th century.
Specifically blame Siemens.
Actually, the one thing I dislike about our electric services the most is the fact that most of it is L-N. I'd much rather have most things be L-L with the ground point about half way between. There ya go, a lower shock hazard right there. The exact voltage and frequency are not as much of the issue to me as the L-N vs. L-L configuration.
Reply to
phil-news-nospam
On this point, I agree with you. A L-L system at 240 V. (120 max to ground) would give all the benefits (higher utilization voltage, lower current, lower insulation requirments (120 to ground) along with an earthed groundED conductor and avoidance of a neutral (whenever possible) and would promote maximum safety. When more safety is needed, a fault sensing GFCI or RCD could be used (on local invidual circuits, and/or as part of the the mains.
The only downside from a LL system, as far as I can determine, is that the mechanical complexity of breaking the circuit (by double ganging the contactors) is increased. The strictly L-N systems seems more suitable for use with a single-gang fuse
Earlier you stated that dryers should be required to have 240V. motors. Also a good point. I would say that this should apply to the larger sizes of window air conditioners as well. Perhaps a 30 amp 240 V. circuit with two hots and one safety ground (no neutral).
I'm not sure what you would do about ranges. The ranges in the USA require a current carrying neutral (for the lower settings, the clock, and the light) although it must be possible to design a range that operates on straight 240 volts as they are apparently the standard in Europe.
How about refrigerators? Are there any advantages to an all 240V refrigerator?
Beachcomber
Reply to
Beachcomber
why 36? or 72?
Actually the choice of 50/60 Hz is a compromise balance between a number of factors including economics. 25Hz was great for slow motors- particularly in the days when one motor was belted to a shaft and various lathes, etc were driven by belt connections to the same shaft. To hell with reading- people should be working. 16 2/3 Hz was/is used in some railway systems. 100Hz was also tried but L and C problems exist. 400Hz is fine for aircraft- smaller and lighter machines which could be driven by high speed turbines as used in aircraft while transmission distances were lower. As to 50 vs 60 Hz -historical (hysterical?) choices - probably including some politics. If you could encourage East Boondock to buy 60 Hz equipment- then they would go to the US for more -rather than to Europe. The Brits had a big Empire so there are more 50Hz systems than 60Hz (Canada is an exception). Clock gearing ratios are simpler at 60Hz (if you can still find a clock with a synchronous motor).
Reply to
Don Kelly
| The only downside from a LL system, as far as I can determine, is that | the mechanical complexity of breaking the circuit (by double ganging | the contactors) is increased. The strictly L-N systems seems more | suitable for use with a single-gang fuse
back in the days of fuses, this was certainly one consideration. The extra switch complexity would have been, too.
It's incandescent lights that mostly need the L-N voltage. But given that the ratio between L-N and L-L varies depending on the chosen phasing system, the design I described chose to use a separate system for lighting. Since incandescent actually benefits from a lower voltage, that's what I aimed for. With everything L-L on one system and everything L-N on another system, there is consistency in voltage between different phasing systems.
The system I chose was 20% higher in voltage and 20% higher in frequency. But it could just as well have been 240 volts L-L at 60 Hz (derived from 120 volts on single phase sources and 138.5 volts on three phase).
| Earlier you stated that dryers should be required to have 240V. | motors. Also a good point. I would say that this should apply to | the larger sizes of window air conditioners as well. Perhaps a 30 | amp 240 V. circuit with two hots and one safety ground (no neutral).
Then you could use a NEMA 6-30. Smaller things like a window air conditioner might only need NEMA 6-15.
| I'm not sure what you would do about ranges. The ranges in the USA | require a current carrying neutral (for the lower settings, the clock, | and the light) although it must be possible to design a range that | operates on straight 240 volts as they are apparently the standard in | Europe.
Just use the design from Europe, but with a small transformer for the light. And operate incandescent lights on 12 volts while at it.
| How about refrigerators? Are there any advantages to an all 240V | refrigerator?
Just like anything else. The current is smaller. The disadvantage is some switching needs to be double pole. But not all of it needs to be, such as the thermostat.
I noted that several computer power supply specs show more efficient operation at 240 volts.
Also, the US 240 volt system is already balanced power, so you get all the benefits of low ground hum that otherwise requires a 60-0-60 system to do that for 120 volt equipment (with the associated risks).
Reply to
phil-news-nospam
AFAIK, all nuke's have 4 pole units. Lower steam pressure & no superheat (ok, B&W units have a little) result in a high steam flow for the size of the plant. The longer blades of a 1,800 RPM unit on the low pressure side are of greater benefit. Even with the lower speed, the 'big' units have 3 double flow low pressure units.
3600 RPM is the realm of gas turbines and coal / nat. gas fired steam units.
Reply to
Matthew Beasley
Hey, I never said it was bad... just pointing out what would be different.
Of course we could just go to DC for most transmission and the frequency wouldn't matter.
Reply to
Matthew Beasley
|> |> |
|> | |> |> There are many aspects of the US/North American system I don't like. |> |> The 60 Hz is about the only thing I do like about it. I'd rather go |> |> on up to 72 Hz. |> |> |> | |> | hmmm... 4320 RPM and 2160 RPM generators. More power in the same size |> | generator, but the turbines would change, some for the better, some for |> the |> | worse. |> | |> | X sub L of the power lines increased by 20%. Charging currents increase |> by |> | 20%. |> |> Oh, well, then let's go to 36 Hz. | | why 36? or 72? | | Actually the choice of 50/60 Hz is a compromise balance between a number of | factors including economics. | 25Hz was great for slow motors- particularly in the days when one motor was | belted to a shaft and various lathes, etc were driven by belt connections to | the same shaft. To hell with reading- people should be working. 16 2/3 Hz | was/is used in some railway systems. 100Hz was also tried but L and C | problems exist. 400Hz is fine for aircraft- smaller and lighter machines | which could be driven by high speed turbines as used in aircraft while | transmission distances were lower. | As to 50 vs 60 Hz -historical (hysterical?) choices - probably including | some politics. If you could encourage East Boondock to buy 60 Hz equipment- | then they would go to the US for more -rather than to Europe. The Brits had | a big Empire so there are more 50Hz systems than 60Hz (Canada is an | exception). Clock gearing ratios are simpler at 60Hz (if you can still find | a clock with a synchronous motor).
I suspect clocks were one basis for choosing 60 Hz. They already have a set of gears for reducing seconds to minutes at 60:1. At 60 Hz they need only one more.
Canada appears to be more influenced by the US than the UK.
I chose 72 Hz more for personal reasons than for technical reason, though. One reason is just to be different. If at a time when 50 and 60 had emerged, proposing a new standard would need to be different to avoid giving one group a specific advantage over another.
Another is that 72 Hz would have allowed using the same transformer core as is now used for 240 volts, but on 288 volts. I chose 288 volts mostly because it had some interesting numbers associated with it. Half the voltage is 144. Divide it by the square root of 3 and you get 166. Or multiply it by the square root of 3 and you get 499. In all cases, the numbers have the last 2 digits a "double", making these somewhat easier for people to say. Obviously not really a good technical reason.
The whole scheme would still work at 60 Hz and 240 volts on the L-L circuits and 24 volts on the L-N circuits. You'd just have either 120 volts to ground or 138.5 volts to ground, depending on whether you get the 240 from single phase or three phase. The idea is to use L-L more and have the same voltage between single phase and three phase.
I'd rather have seen TV run at 72 Hz. As you know, early TV frame rates were based on power frequency rates. We don't need to do that today, and haven't needed to for decades. Today some TVs do overscan anyway, and they tend to look a long better. 72 Hz is exactly 3 times the 24 fps traditional to film. But 60 Hz means some frames are 2 times and some are 3 times. It looks better when the multiplication is consistent.
Do you know why Japan has split 50 Hz and 60 Hz? At least that means there are some products made by manufacturers that have a motive to make sure they work on either 50 Hz or 60 Hz. I'll guess that they use the lower 100 volts to make the 50 Hz work on transformers that were really intended to operate on 120 volts at 60 Hz.
Reply to
phil-news-nospam
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|> |> |
|> | |> |> There are many aspects of the US/North American system I don't like. |> |> The 60 Hz is about the only thing I do like about it. I'd rather go |> |> on up to 72 Hz. |> |> |> | |> | hmmm... 4320 RPM and 2160 RPM generators. More power in the same size |> | generator, but the turbines would change, some for the better, some for |> the |> | worse. |> | |> | X sub L of the power lines increased by 20%. Charging currents increase |> by |> | 20%. |> |> Oh, well, then let's go to 36 Hz. |> | | Hey, I never said it was bad... just pointing out what would be different. | | Of course we could just go to DC for most transmission and the frequency | wouldn't matter.
For long distance transmission, that is already happening to some extent now. Given the effective transmission distances have increased based on the way power is traded around, and the heavy reliance on the grid that was originally intended for backup purposes, DC might be a better choice for even more.
Reply to
phil-news-nospam
Canada and the US are heavily interconnected. There is not much in the way of exclusive separation of the US-Canada electrical border.
As engineers, I would say that this is a fairly convoluted way of making a an intelligent selection. I think this sentiment is found more in the European countries than anywhere in North America. (To give a group a specific advantage might hurt the feelings of the others...even if the original group has the better system... Wow!?)
It reminds me of my mother's philosophy. "Each child must be treated fairly. If one has less, then it is my duty to give him more than the other one".
It also reminds me of communism.
Something so important with so much impact on future generations should be wisely chosen on having the best technical considerations with regard to economy, safety, ease of implementation, and a whole lot of other factors.
Edison thought DC was better. Westinghouse, Tesla, and when he was off on his own, Edison's own secretary Samuel Insull, saw the economy of an AC distribution system. The 1893 Chicago Columbian exhibition spread the wisdom and gospel of AC. The world proved it was economical, even though high voltage DC transmission were eventually perfected in the electronic age.
Beachcomber
Reply to
Beachcomber
connections to
I read on some obscure Web site that the reason for 25 Hz was basically that the Niagara Falls turbines had been ordered before they'd quite made up their mind how to get the power out (AC? DC? Compressed air?) and they turned out to be the wrong RPM to make an alternator at 30 Hz. Westinghouse wanted 30 Hz for motors and 60 Hz for lighting, but settled on 25 Hz at Niagara which then spread over the immediate area. By the 1950's Ontario had to go around and replace or modify a bunch of appliances when they decided to go to 60 Hz.
including
Until just after WWII, parts of California were 50 Hz. And Japan to this day is split in half, part 50 and part 60 Hz. The Itaipu project has some 50 Hz generators and some 60 Hz. And Ontario still has a couple of 25 Hz powerhouses on the Niagara, in case a frequency converter fails some day....
Bill
Reply to
Bill Shymanski
I thought the conversion happened during WWII, driven by connection of Hoover dam to the LA area. Mexico City was post war.
I'm curious about the story behind that... Not just the anactodtal, but the full blown story.
The treaty behind the dam gives 1/2 of the power to Peru and 1/2 to Brazil. The Peru generators are 60Hz and the Brazilian generators are 50Hz. The most amusing part is that more than half of the 60Hz output is converted to DC and sent to Brazil to be converted to 50Hz since Itaipu produces more power than Peru needs.
Reply to
Matthew Beasley
| |>I suspect clocks were one basis for choosing 60 Hz. They already have a |>set of gears for reducing seconds to minutes at 60:1. At 60 Hz they need |>only one more. |> |>Canada appears to be more influenced by the US than the UK. | | Canada and the US are heavily interconnected. There is not much in | the way of exclusive separation of the US-Canada electrical border. |> |>I chose 72 Hz more for personal reasons than for technical reason, though. |>One reason is just to be different. If at a time when 50 and 60 had emerged, |>proposing a new standard would need to be different to avoid giving one group |>a specific advantage over another. |> | As engineers, I would say that this is a fairly convoluted way of | making a an intelligent selection. I think this sentiment is found | more in the European countries than anywhere in North America. (To | give a group a specific advantage might hurt the feelings of the | others...even if the original group has the better system... Wow!?)
It's not about hurting feelings. There are real economic issues that are involved with decisions like that. It's easier to make decisions like that if you can go back in time before anyone has committed to it.
| It reminds me of my mother's philosophy. "Each child must be treated | fairly. If one has less, then it is my duty to give him more than the | other one". | | It also reminds me of communism.
It does not remind me of communism at all. It reminds me of the separation of government and business. Communism would have no businesses at all with the government running everything. But we do get an advantage of government establishing standards where there is economic disadvantage to having incompatibilities.
| Something so important with so much impact on future generations | should be wisely chosen on having the best technical considerations | with regard to economy, safety, ease of implementation, and a whole | lot of other factors.
I agree. I also believe that has never been done with any electrical system design.
| Edison thought DC was better. Westinghouse, Tesla, and when he was | off on his own, Edison's own secretary Samuel Insull, saw the economy | of an AC distribution system. The 1893 Chicago Columbian exhibition | spread the wisdom and gospel of AC. The world proved it was | economical, even though high voltage DC transmission were eventually | perfected in the electronic age.
I read that Tesla wanted 80 Hz or more.
DC transmission is practical now. But could we also do this for the distribution layer now? Would DC to the service drop be practical? If so, then we could freely choose whatever AC frequency we want, or just use the DC as it is.
Of course DC comes with it's own interesting issues. It's less practical for simpler motors, but probably just fine for controlled motors. It has no zero crossover, so fuses and circuit breaker fault issues are more significant.
DC GFCI breakers exist, but I bet they are more complex.
I'm not opposed to having DC all the way to the home. But just how safe and reliable are the means to step the voltage down? Is there any failure mode that makes it more likely to unleash distribution voltages to the home circuits than we would have with pole pig and pad mount transformers?
What voltage should we drop to homes in DC? 240?
Reply to
phil-news-nospam
I think it comes down to a basic knowledge of physics. DC is coming into play again because people are installing solar and wind power systems.
High voltage is required for long distance transmission, but the world has not, and in my opinion, is not going to return to widespread dc transmission and distribution. Electrical engineers would mostly agree that 1000 volts per mile makes sense for AC transmission.
With DC, at present, there is no safe and economical way of converting say 115, 000 kv at thousands of locations to a safe utiliazation voltage at many many multiple locations. The installations that do support terminations for dc transmission lines are large, largely custom designed, and very expensive.
Personally, I don't think the era of a DC central station in every town is going to come back. Do you have information to the contrary?
Beachcomber
Reply to
Beachcomber
| |> |>I'm not opposed to having DC all the way to the home. But just how safe |>and reliable are the means to step the voltage down? Is there any failure |>mode that makes it more likely to unleash distribution voltages to the |>home circuits than we would have with pole pig and pad mount transformers? |> |>What voltage should we drop to homes in DC? 240? |> | | I think it comes down to a basic knowledge of physics. DC is coming | into play again because people are installing solar and wind power | systems.
And maybe I need to consider that direction given the not so great level of inverters I'm finding on the market.
| High voltage is required for long distance transmission, but the world | has not, and in my opinion, is not going to return to widespread dc | transmission and distribution. Electrical engineers would mostly | agree that 1000 volts per mile makes sense for AC transmission. | | With DC, at present, there is no safe and economical way of converting | say 115, 000 kv at thousands of locations to a safe utiliazation | voltage at many many multiple locations. The installations that do | support terminations for dc transmission lines are large, largely | custom designed, and very expensive.
So basically, it can be done for special cases, but it's not practical for the common cases (at least not yet).
| Personally, I don't think the era of a DC central station in every | town is going to come back. Do you have information to the contrary?
I have no such info. What I am wondering about is, if it would be possible or practical to distribute power that stays DC all the way from where it is generated to to the home/office. I guess the answers would be "perhaps and no".
I guess we are stuck with AC from the utility in my lifetime but might need to consider DC utilization for off-grid home power systems.
Reply to
phil-news-nospam
-------------- Canada was/is more influenced by the US as they are (electrically) closely tied from after the original multiple frequency options shook out- sheer economics and practicality. As to TV's the line frequency really shouldn't matter provided that the refresh rate (V? can't remember) is generated internally and not from the line. Generation from the line would lead to problems with synchronisation with the signal. 50-60 Hz is OK for magnetic deflection.
I don't know the historical reason for the split system in Japan - probably the initial reason was that in some regions UK salesmen did better than US salesmen in an era where rampant salesmanship and limited regional coordination existed. In the US and Canada, there was some of the same going on where each region had its own rules (probably the main manufacturers, GE and Westinghouse had a great deal to do with the standardisation of frequency- along the lines that Henry Ford used for the choice of car colours. "you want 72 Hz"- we got 60Hz (actually 120 alternations/sec or "alts" as I have seen on a 1912 motor nameplate)-take it or leave it". This leads to a response to what you have said about DC transmission. There are 3 basic situations where DC transmission is the best choice: a) High voltage long distance point to point interconnections - cheaper lines but terminals more expensive so $ balance tips in favour of DC for long distances. (e.g Manitoba's Nelson river system) b)Potential or actual frequency differences (even of a fraction of a Hertz)between systems where an asynchronous tie is of benefit in terms of system stability Some DC ties are back to back rectifier inverters because of this (Japan-50-60Hz, Eel River New Brunswick Canada -first solid state converters in use 60-60 Hz ) Both of these are of concern in the Western DC link from Oregon south to California and 4 corners region of US ( where rapid control of power transfer aids in stability of the parallel AC system) and in ties from Northern Quebec to New York State. c) long underground or underwater lines - a rough rule of thumb is that 30 miles of cable is equivalent to 300 miles of overhead line in terms of capacitance and associated problems.
The main disadvantage of DC 1)since a station has not only transformers but also rectifier inverters and associated filters the DC stations are expensive-so that economics indicate DC for long lines or special cases as above.
2)In addition, there is a problem with circuit breakers and switching. This is far more costly and often beyond present technology for DC. With AC, circuit breakers do not normally "break" the current but simply take advantage of natural current zeros - preventing re-ignition of the arc. On a small scale look at simple switches. Open a knife switch 1/4 inch on AC at 120V, 10A and there is a small spark. Do it on DC under the same situation and there will be a sustained arc flaring out a good half inch or more from the contacts. (proven good for lighting cigarettes and if done carefully, less dangerous than smoking the cigarette- I am a reformed smoker). Why is this important? Simply put, a grid system depends on circuit breakers and transformers. Hence DC for "grid" use is, technically and economically, not a viable option except as indicated above under a)b)c).
Reply to
Don Kelly

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