Yes, but consider a continuous load with MD of 80 KVA. What is the minimum capacity of transformer? Is not equal to 80x1.25=100KVA?
Maximum recommended motor hp served at 480v??
- Thread starter joshtrevino
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Yes, but consider a continuous load with MD of 80 KVA. What is the minimum capacity of transformer? Is not equal to 80x1.25=100KVA?
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- Massachusetts
The minimum NEC rating of a transformer with 80KVA of continuous load is 80 KVA.
There is no NEC '80% rule' for transformers.
You are complying with 90.1(B) :thumbsdown:.
- Location
- Massachusetts
Nope, 90.1(B) has nothing to do with my response.
How about this, how about you post the NEC code section you believe requires a transformers load to be under 80% OR you just drop this silliness?
Nope, 90.1(B) has nothing to do with my response.
How about this, how about you post the NEC code section you believe requires a transformers load to be under 80% OR you just drop this silliness?
I have to quote also the same 90.1(B), which recommends spare capcity to be built into an electrical equipment.
I do not know what is silly about this.
Oh! the topic deals about electrical design aspects about which you appear to know not very much.
- Location
- Massachusetts
Now you are changing the topic.
Is the topic what the NEC requires or is the topic what a good design should include?
Pick a topic, stick with it and we can discuss, if you want to keep jumping between topics you will be discussing it with yourself.
Fantastic response, if you can't prove your point try to change the subject. :thumbsup:
No.
The topic is what the NEC recommends to include in a good design (90.1B), which every one here knows. So stop kidding.
I do not see where the topic is changed. Would you elaborate further?
petersonra
Senior Member
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- Northern illinois
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- engineer
The NEC also says it is NOT a design manual, and anyway, nothing in article 90 is enforceable.
I think you are making a logic leap from conductor ampacity requirements and OCPD requirements to transformer sizing that just is not found in the code.
I think you are making a logic leap from conductor ampacity requirements and OCPD requirements to transformer sizing that just is not found in the code.
weressl
Esteemed Member
As I said demonstarting a fundamental lack of uderstanding of what the Code is, what purpose it serves and how it is supposed to work. Makes me wonder what interest somebody from India and the telcom industry have in the NEC that is not aplicable to their filed of work, besides of engaging in polemics.....
shamsdebout
Senior Member
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This post started out very informative and then became very amusing. Seems like a nice balance.
- Location
- Massachusetts
Recommends is not the same as require and nowhere in 90.1(B) does it indicate 80% is a figure to use. As a matter of fact 90.1(B) does not even recommend providing extra capacity, it simply tells us that using the NEC minumums may not be enough.
If you are talking about the informational note after that section.
That does not mention 80% and is not part of the 'code' at all. It is just helpful information.
As has been said, the NEC is just the minimums not any type of 'design'.
Not really me. See table 2.2 on page no.2-10 of the book (after purchasing it, of course)
http://books.google.co.in/books/abo...ower_systems.html?id=k-NSAAAAMAAJ&redir_esc=y
In the above book the authors are really making the 'leap' and it is a correct one as far as the OP is concerned.
I am from India and working as an electrical engineer in Telecom Industry.
I decided to assess the worth of NEC and the guys using it.....
. Just joking.There are, of course, some commonalities between American and Indian Electrical Systems. I just
want to learn and to better grasp the common working principles.
Thanks.
weressl
Esteemed Member
I am from India and working as an electrical engineer in Telecom Industry.
I decided to assess the worth of NEC and the guys using it.....
There are, of course, some commonalities between American and Indian Electrical Systems. I just
want to learn and to better grasp the common working principles.
Thanks.
It is hard to learn when you know it all.........
Really?
Thanks.
weressl
Esteemed Member
...again diverting, introducing new source without actually quoting what the substance of that argument is so people can not even engage it substantially. Not a constructive demonstration of willing to dialogue, never-mind learning.
petersonra
Senior Member
- Location
- Northern illinois
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- engineer
this book is not the NEC.
weressl & petersonra:
Our main contention is the content of the second sentence below
I based both the sentences from that book just to help the OP.
Our main contention is the content of the second sentence below
I based both the sentences from that book just to help the OP.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Once again the book is not the NEC. What it says may make sense, might even be good design criteria, but it is not the NEC. If the book says the NEC requires something that is not actually in the NEC, the book is wrong.
In any case, a 500HP motor is only about 372kW. I do not have the book, nor did you paste enough from the book for anyone to know what it is saying in its proper context. It is quite possible that the authors believe one should have a transformer supplying a motor that is some size larger than the largest motor to account for starting current in across the line situations. That is not a NEC issue. it is solely a design issue.
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weressl
Esteemed Member
The bold sentence is an untrue assertion, and the first one has insufficient data to be either way.
There is no such statement in the NEC. You were requested to supply the specific pararaph, verbatim and haven't done so because you COULD not do so, it is simmply not there.
The 5:1 or greater ratio for staring duty is an unscientific, tradesmen 'rule' without any engineering done.
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