Distribution voltages???????????

[Pootnaigle]

can anyone enlighten me why there are sooooooo many different dist voltages sooooooo close together. some of em are just a few hundred volts apart ex. 12470 and 13.2 and 13.8 and maybe 14.4...... all of em require different windings to get the same secondary voltages which are standardized 120/240 , 120/208, 277/480 or480. Seems like Transmission voltages are pretty much standardised and Lightning arrestors are made to work on a variety of voltages.
Wouldnt it be cheaper and faster if Xfmr manufacturers didnt hafta constantly swap from one to another to wind one? And neighboring utilities mite could share Transformers in an emergency. I have always wondered about this since in my area the nearest utility other than ours uses 12.470 while we use 13.2and the industrial sector all use 13.8 I admit 34.5 is gettin pretty commonplace nowadays but that usta be transmission ............. Any body know why all these bastard voltages?

[OutRigger]

I can't say why to all but 7200 is common on the east coast and 13.2 is and 14.4. A lot of company,s use 7200 because of trees are not kelp trim are because of man hours to covert. Now why 13.2 or 14.4 I can't say but 34.5 or 44 if you use these it limits your time when you can work. And you have to have a well plaind system and every one it not going to plan ahead.

[scammy]

one is geographical location ,,just in time thinking ,,what works now,,sometimes it old 4 kv ,,because in the day it worked and we never upgraded,,,sometimes its easyer to change taps because it is too far frome the sub,,alott of reasons ,,it keeps you on your feet,,scammy

[Squizzy]

We are moving all our HV to 22kV and the vast majority already is still a little 6.6kV and 11kV around....

[Pootnaigle]

I dont guess yer gettin my drift here. There is no significsnt savings in say 13.2 and 13,8 amp wise, and certainly not much between 13.8 and 14.4 I would assume that back in the day most everything was 4160 and due to load constraints it had to be upgraded . that bein said why so many different voltages so close together for the next step up. dont make sense to me,

[Patriot]

What I have seen is that most public utillities ( REA and Muni's) have one or two common distribution volatages. But! BUT, the investor owned, having bought and combined several neighboring utillities as they grew, have every thing under the sun,. They inherit the previous utillities crap and have to live with it and try to convert as time goes by. We have 2400 delta, 2.4/4.1kv, 7,2/12.5kv, 7.2kv delta,12kv corner ground, 12/20kv, 14.4/24.9kv, and my favorite 19.9/34.5kv. All distribution. And then there are the transmission voltages! In another shop for the same company, you can add 13.8 to that mix, same company!

[Trampbag]

In a word.


Engineers.


The scariest word to linemen and the trade. Each and every one of them think they have a better idea.

[Trampbag]

Ergo, because you can order transformers in any voltage you care for from the manufacturers, GE, Westinghouse, ect, every engineer designing a new system will change things to his way of thinking. A few wraps more or less in the windings and are not more expensive. This was very prevalent prior to WWII, and shortly after.

In the ‘50’s utilities in North America were standardising on voltage (120/240v and 60 cycle frequency) and this “individuality” slowed down a lot but didn’t completely disappear. One utility built a transmission line in the ‘60’s and decided the 138kV was too low and 230kV was too high so the engineers settled for 170kV, go figure. Again the transmission transformers had to be ordered specially, just as the present, and so it costs no more the “have it your way”.

Large utilities order so many distribution transformers that even today there are differences in them from company to company. The same applies to other material used in the industry.

So, the short answer to the question is:

Engineers!!!

[Bull Dog]

You got it right tramp. We have every type of voltage you can think of 345kv on down. 2200, 4400, 7200, 7970, 14400, 24000, 32000, 69000, 138000, 34500 and all the low voltages from 120 240-277 480-120 208-240 480 got to know them all and have equipment for all. The other fella that mentioned utilities that bought out others has a good point also. Thats how we inherited a few strange voltages and weird 3phase banks.

[Pootnaigle]

OK Trampbag I spoze yer answer is bout as good as I'll get.I also unnerstand the inherentence thang .I spoze it goes wifout sayin I jus dont unnerstand them damn engineers line of reasonin.