Why Do Power Systems Have Voltage Multiples?

For no reason at all - Forest Gump.

This is the n*11 time this question is asked.

See previous threads regarding this commonly-asked question.

Given the number of industrial power transmission and distribution questions you have asked, perhaps you should invest in purchasing a book on the subject to help cover a lot of the basics in your new area of interest. There is always the internet and Wikipedia, but if you are starting to work in the power transmission and distribution area a book on the subject (or better yet a university course) is a much better and broader option (I am assuming by your previous questions on CR4 that you have undergone some form of electrical engineering training, just not in the field of power transmission and distribution).

Why do so many people ask this same question?

maybe bcos it is not included in the high school books or the teachers' overlook this topic at colleges :-)

BECAUSE THEY DON'T KNOW THE ANSWER. WHY WOULD THEY ASK A QUSTION IF THEY KNEW THE ANSWER. NOW HOW HARD WAS THAT TO FIGURE OUT ? SURELY YOU DON'T NEED A UNIVERSITY EDUCATION TO FIGURE THAT OUT.

Why do you enter into discussions that you are not interested in commenting on?

duhh, I did comment on it and in fact you responded to my comment, so I guess that says alot about your level of intelligence.

Now why don't you go off and change a light bulb, which is probably all that you are capable of doing. Leave the real engineering to the likes of me.

rgds

Christine Fandel Kant

Please visit my website

www.youareanass.com

Guest,

Just so you know I was replying to JRaef's answer, not yours. I was actually supporting your stance that people should not be made to feel ashamed for not knowing everything.

For the record, I am very good at changing light bulbs; do you have any that need to be replaced?

Mr EElectrician, please accept my apology for my response. I did not read the post correctly and I felt (incorrectly) that you were just having a go at me because I am not a registered member.

I feel ashmed now with my response to you.

Again, please accept my sincere apology.

I hopefully have the ability to change my own light bulbs but if I ever get stuck then I will certainly ask for your expertise, I am sure that is not all you are expert at - after all a girl can't do everything herself and batteries do not last that long !!

rgds

Christine

Hello Guest (Christine),

Well done for the apology. Sorry often is the hardest word?

It is the nature of the site that one post does not necessarily follow the previous one, in numerical order. There could be a row of 0-9, then, because people have been replying to other than the first original post, the post order can jump to 29 or 56?

It pays to tread lightly, guest or not, as you may be replying and 'having a go' at a completely innocent person! But 'having a go', under these circumstances on this site, will get you nowhere other than possibly 'ignored'.

You can start afresh now, and you may have need for help yourself here one day?! Courtesy costs nothing does it? And you may even meet some good friends?

Take care and happy holiday..............

PS. You have signed the bottom of a couple of posts "Christine". Why not use that as your user name?.................Just a suggestion, OK?

Hello Guest, AKA Christine,

I was wondering about your site. Do you mind if I ask a personal question? Do have anything wrong with your back? There seems to be a lots of back and spinal injuries related sponsors, that all.

I am honestly interested, and am not being insulting OK?

Take care, and try to have patients. I like your name.

Happy holiday Christine.....................

There has to be some kind of standard for things to actually work with the power system.

You would not want to be buying tools or products that would blow up when plugged in would you ?

Or products that demand more power than was available to operate.

The bigger issue is, this "multiples of 11" issue is NOT a universal truth, just a phenomenon in some locations. So that, to me is proof of two things:

1) There is nothing to it besides coincidence, or maybe a lazy engineer at some time who had a penchant for prime numbers.

2) The people who keep asking this question have a parochial view of the world. Here in North America we have 208, 230, 480, 575, 2300, 4160, 6600, 6900, 7200, 10,000, 12,470, blah blah blah. I challenge anyone to find a repeating pattern in there somewhere.

Hello koshy.dennis:,

I can see three 'doubles' in your list.

However it is not the norm. It is all about:

What is considered safe practice.

Whoever designed some of the first power transmissions stuff.

And the several Protocols used in different Countries.

=======================================

I checked out the number of related questions from you, and I am hoping you have this as an interest rather than as part of the power distribution Industry. Because I do not want to be anywhere near the area you are 'in charge of'.

Pun intended. Go to college or Uni' and or get a decent book or DVD.

No insult intended OK? But in checking out the various other things you have asked on very similar subjects, you should have gotten and known some of these questions by now?

Take care............AND I MEAN THAT!

Long back in my electrical Engg course, my professor has indeed told me about the reason, the 11KV is not a coincidence,

In the beginning, it was a preferred voltage, afterwards, this has become tradition.

May be some historian can tell. For me after some 40 years, the memory has fogged into the practicallities rather than the theories.

best i could get is that the generator voltage in RMS is 4.44fNΦ which along with the winding factors may come pretty near 4.4fNΦ

this might have been, but I am not sure.

Still 11KV is quite a co-incident people must have gone for some round figure say 10KV unless something

Because 11KV rms neither provides a peak to peak of a round figure (15.5KV), nor L-L voltage (19.05KV) I will try to find out the reason, don't know whether can trace the course notes, the FKK may help, i think I have the book still. But somebody else may remember / ask the professors (we seem to have quite a few students around us, grey ones)

Hello SB,

how about this?

http://www.eei.org/industry_issues/industry_overview_and_statistics/history

I found it after sending my two P's worth in.

Take care...............

GA for the site by the way what are the Ps? sb

Hello sb,

P's means Pennies. I am English and we do not have cents! Is that why all English people are stupid?

Tar for the GA!

Doubt I will catch Del up but, all goes to get the 'GA coffers' a little more plump.

Take care...........

They are not. BabyBear's link does a reasonable job of describing how various independant power distributors arrived at a standard. According to the website this involved negotiation and bribary (the US is a capitolist economy).

As a matter of fact, voltage standards change over time. The 440v standard that you mentioned above was used in the US in the 1970's, but the current standard is 480v. Also changed - 110v is now 120v, 220v is now 240v. In the near future I expect to see these go up an additional 10v because my local providers are already supplying 128v/248v, 1ph and 488v, 3ph to industrial users.

Hello EElectrician:

I thank you for your mention Sir! I try.

Can I ask you, when you start by saying "They are not", am I right to assume you mean all electrical supplies are not the same? Just wondered.

The US is a big place and, often seems a little like small countries linked together, with often, States having different laws, and such?

Take care and have a great holiday!

Hi babybear,

I always try to give credit where it is do.

What I meant by "they are not" is exactly that. In AC only 1 voltage has to be initially decided on for a standard basis. After that the simplest engineering solution is to make all the other voltages in your system use transformers based on whole number ratios so you don't have to purchase custom transformers that use fractional ratios at higher cost.

If you start with a low voltage standard of 110/220 then you can derive the rest of Koshi's list (440V,11KV,33KV,66KV,110KV,220KV) using whole number ratios:

220/440 = 1:2

440/11k = 1:25

11k/33k = 1:3

33k/66k = 1:2

11k/110k = 1:10

110k/220k = 1:2

All of the numbers in the list happen to be multiples of 11, but only because we started with a multiple of 11. If you started with 100, and did your best to keep cost down, then everything would be multiples of 10.

Hello EElectrician:

Thank you for your reply post.

I always try to do the best I can..........Don't always work, but I try!

I see what you mean, and you can only work from one number to start It cannot be done any other way. It just would not make sense. You would end up having purpose made transformers that you would have to over engineer as you would not know what voltage you may need to put through? Not bright with electrics. Can't always recall the terminology!

Take care, and have a great holiday...............

The really sad thing is that despite the volume of posts in this thread I have not heard any response from Henrry (the originator of this discussion). I am afraid that some of the comments posted early in the thread may have discouraged him.

I generally try to give someone a little information at a time rather than throwing the book at them when trying to answer a question. This technique was always challenging for me as a student, but it really helped me in the long run by making me more self-reliant.

Hello EElectrician:

I had just checked to see if the OP had responded. As you say he hasn't.

I just gave my opinion. And he should be proud because it has turned into a good interesting thread!

Take care, and happy holiday!..................

what are the voltage output at generator level ? as per wiki, it is 11KV or 22KV, at our place also it is the same, as is in most of the countries I know. However recently I saw a paper of Alsthom for high voltage generator with slightly off 78KV (not too off i presume and still not a round figure). The transmission is always very flexible (courtesy transformers) but still people try multiples. All other things are designable to the voltage - insulators etc.

And ofcourse like to know "what are not" I presume it is "All the English are not stupid" now which class did you put babybear into ?

what about all the other countries generator voltages? CNPOWER?

Hello Guest,

for your rushed explanation.........you get a GA!

Take care and watch the spelling!

Have a great holiday................

well

when i asked this question in engineering class i was told, since voltage wave is sinusoidal in shape(almost), and the formfactor of sinewave is 1.1. If a voltage wave is a multiple of its formfactor ,i.e 1.1, it will reduce the harmonic wave. this is the reason for all voltages to be multiples of 11(110V,220V,440,11kv).......

correct me if i am wrong