45 KVA transformer max amperage?

[iwire]

Engineers can be such an anal pain in the ...

I am not promoting 'amp adding'. As a matter of fact I dislike that method, I don't see an advantage only pitfalls

I am only pointing that to some of us, those of us common folks it seems pretty clear what the OP was saying.

And while it would be great if we all spoke the same language there is very little point in trying to make the OP walk before they can crawl. To me the only reason people want to do this is to show off their mad skills. To me that generally only confuses the direct issue the OP is asking about.

For instance there is an engineer on this forum that will almost always jump in to point out 120/240 is not the same as 240/120. Well to a newbie that can sound very off topic if they asked about running a feeder from a home to a garage.

There is another engineer here that regularly complains the questions were not asked correctly.

Now both of the engineers I am thinking of, hell all the regulars here that also happen to be engineers are very talented, knowledgable and valuable assets to this forum. I am personally very greatful for their participation.

My point here is maybe we could do better trying to answer the question asked before trying to get the OP to ask the question in a way that pleases us.

OK, I feel better now. :dunce:

 

[mivey]

Engineers can be such...

Why thank you.

I am not promoting 'amp adding'.

Whew! I was worried there for a minute. I guess I'll call the others and stop the intervention.

I am only pointing that to some of us, those of us common folks it seems pretty clear what the OP was saying.

And here I thought I was a man of the peoples.

And while it would be great if we all spoke the same language there is very little point in trying to make the OP walk before they can crawl. To me the only reason people want to do this is to show off their mad skills. To me that generally only confuses the direct issue the OP is asking about.

Sometimes. But it may be that some have learned to try and answer the question that was asked, not what we think was asked. Clarification is part and parcel of many engineer's daily work. Some also spend time helping others learn and to do that you have to find out specifically what is causing them problems.

Now both of the engineers I am thinking of, hell all the regulars here that also happen to be engineers are very talented, knowledgable and valuable assets to this forum. I am personally very greatful for their participation.

Too late to suck up now brother. Oh it's on like Donkey Kong!!!

My point here is maybe we could do better trying to answer the question asked before trying to get the OP to ask the question in a way that pleases us.

So yes or no or just a number with no explanation or help for incorrect data? I guess if that's what works for the common folks...

Do you choose to ignore the error and just say "No" for this?:

Is it correct to say that for a three-phase 45 kva transformer, the load on each one of 3 lines going to the electrical panel should not exceed 80 Amps ?"

Do you choose to ignore the error in this part of the question?:

If the load is properly balanced, this will produce maximum 120 Amps at 208 V ( 43 kVA ) or 240 Amps at 110 V ( 45 kVA )

Are you going to assume the poster just made a typo or are you going to find out if they need additional info/help?

In light of the errors in the previous questions, including balanced and whatnot, are you going to think the poster might have made yet another error in this post or is meaning something that makes sense to you if you extrapolate it just right?:

Does it mean, if properly balanced a 45 kVA three-phase transformer can supply a whopping 375 Amps at 120 volts ?

OK, I feel better now. :dunce:

So glad you got that off your chest. I know I'll sleep better knowing that.

 

[iwire]

Go have fun with this one http://forums.mikeholt.com/showthread.php?t=167840

 

[mivey]

Go have fun with this one http://forums.mikeholt.com/showthread.php?t=167840

I probably need to get the common folk interpretation first.

 

[iwire]

I probably need to get the common folk interpretation first.

You can't succeed unless you try.

This knuckle dragger has your back if you get into trouble.

 

[mivey]

You can't succeed unless you try.

This knuckle dragger has your back if you get into trouble.

Oh sure, throw the delicate engineer to the wolves.

 

[iwire]

OK, I had to put down the Ipad and move to a real keyboard for this.

Please keep in mind my comments below apply to many threads not just this thread specifically.

Whew! I was worried there for a minute. I guess I'll call the others and stop the intervention.

I know, I looked out my window and saw a bunch of guys with pocket protectors on my porch fighting over the proper way to ring my doorbell and if the button at my door is for the bell because it was not labeled as such. .

And here I thought I was a man of the peoples.

Maybe back in the day, but you made what can only be considered a smart choice and elevated yourself.

Clarification is part and parcel of many engineer's daily work.

Exactly, however many times I feel like that habit tends to chase newbies off. (Like when someone complains a question was not asked correctly)

Some also spend time helping others learn and to do that you have to find out specifically what is causing them problems.

No argument there, but IMPO it is more helpful(1) to try to answer question to the best of our ability using the info given and follow that up with friendly questions.

So yes or no or just a number with no explanation or help for incorrect data?

Yes, that with non-confrontational follow up questions. Not 'You are talking to us wrong'.

I guess if that's what works for the common folks...

If it means they stick around and feel comfortable here it has worked.

Do you choose to ignore the error and just say "No" for this?:

I might.

Do you choose to ignore the error in this part of the question?: Are you going to assume the poster just made a typo or are you going to find out if they need additional info/help?

We are covering the same ground, I am going to respond in a way that I think helps the person even if that means I appear less knowledgeable than I am. (2)

In light of the errors in the previous questions, including balanced and whatnot, are you going to think the poster might have made yet another error in this post or is meaning something that makes sense to you if you extrapolate it just right?

I think anything is always a possibility but it irks me when posters are given a hard time for not knowing how to properly phrase a question. I do not think it is productive. Many people are nervous posting on these forums and we should try to be welcoming.

So glad you got that off your chest. I know I'll sleep better knowing that.

I 'done good'. I will ask my wife to put a gold star on my chart today.






(1)Helpful takes many forms, to me making someone feel comfortable with asking questions and not making them feel undereducated is much more important than the specifics of the question itself.


(2) Unless I don't like them, then my evil side takes over. I am trying to work on that fault.

 

[mivey]

I looked out my window and saw a bunch of guys with pocket protectors on my porch fighting over the proper way to ring my doorbell and if the button at my door is for the bell because it was not labeled as such. .

LOL. Thanks for that. I dropped in today to try to clear my head from some analysis I've been running so I'm all good now. :thumbsup:

Exactly, however many times I feel like that habit tends to chase newbies off. (Like when someone complains a question was not asked correctly)

No argument there, but IMPO it is more helpful(1) to try to answer question to the best of our ability using the info given and follow that up with friendly questions.

Yes, that with non-confrontational follow up questions. Not 'You are talking to us wrong'.

If it means they stick around and feel comfortable here it has worked.

All good thoughts to keep in mind. Sometimes I expect too much. Reminds me of an old boss I used to have.

I am going to respond in a way that I think helps the person even if that means I appear less knowledgeable than I am.

Gasp! If we could just bottle that and put it in the engineer's drinking water the world might just be happier place!

I think anything is always a possibility but it irks me when posters are given a hard time for not knowing how to properly phrase a question. I do not think it is productive. Many people are nervous posting on these forums and we should try to be welcoming.

I guess we spend to much time talking among ourselves and forget to consider the poster's forum age.

making someone feel comfortable with asking questions and not making them feel undereducated is much more important than the specifics of the question itself.

I may be guilty but that is never my intent. We all have to learn and I love teaching. Teaching is a good refresher and I also learn more in the process. What wrinkles me is when someone claims to be an expert and starts throwing down, then I don't really feel obligated to be so careful.

Unless I don't like them, then my evil side takes over. I am trying to work on that fault.

A kinder, gentler Iwire. I just feel warm and fuzzy all over.

 

[kingpb]

And after all that.....

120/240 is NOT the same as 240/120; nor is 120/208Y the same as 208Y/120.

At least according to US practices.

 

[don_resqcapt19]

And after all that.....

120/240 is NOT the same as 240/120; nor is 120/208Y the same as 208Y/120.

At least according to US practices.

Other than formal presentations, classes and in this forum, I don't think I have ever heard anyone state a voltage with the higher voltage first. I have never heard that in the field from either an engineer or an electrician.

Its like a lot of things, the "slang" terms work just fine most of the time.

 

[mwm1752]

Whew --- what a read -- lets see each phase has the capacity to supply 100A worth of 120v continuous load branch circuits -- about 6 fully loaded continuous loads per phase = 18 circuits -- Just pokin the bee's nest
Who's going to bring up OCDP :rotflmao: My bad I did

 

[kingpb]

Other than formal presentations, classes and in this forum, I don't think I have ever heard anyone state a voltage with the higher voltage first. I have never heard that in the field from either an engineer or an electrician.

Its like a lot of things, the "slang" terms work just fine most of the time.

That's Ok, you probably still call them "PT"s too.:jawdrop:

Try putting 120/208V on a set of plans; I'm going to bid it as a single phase system, then CO the heck out of you and laugh every time I cash the check. :thumbsup:

 

[iwire]

That's Ok, you probably still call them "PT"s too.:jawdrop:

Try putting 120/208V on a set of plans; I'm going to bid it as a single phase system, then CO the heck out of you and laugh every time I cash the check. :thumbsup:

It's not his fault you did not RFI.

 

[kingpb]

It's not his fault you did not RFI.

That is what someone might presume, except why RFI? :? If it says 120/208V, then standards dictate that is a single phase system; ANSI C84 is quite clear.

Voltages in NEC are covered in Article 100, and more specifically 220.5 :happyyes:; consistent with C84.

RFI? I don't need no stink'in RFI! But you will pay my over inflated CO

Now if your nice, and buy me donuts and coffee when I come on sight, I might let it slide :angel:

 

[Jraef]

Other than formal presentations, classes and in this forum, I don't think I have ever heard anyone state a voltage with the higher voltage first. I have never heard that in the field from either an engineer or an electrician.

Its like a lot of things, the "slang" terms work just fine most of the time.

Ooh, ooh, I can contribute to that tangent!

I once did a research paper in college on that exact subject. Turns out there IS an official meaning to the specific order in which the numbers are listed, and they ARE different. I can't for the life of me remember what the answer was right now, I drowned those brain cells in alcohol I guess. But I DID actually post this in here, or somewhere, a few years ago when a similar subject came up. I had dug up that old paper at that time, but it would be gone now because I have purged myself of old paperwork. If I can find my old post however, I'll link it or repeat it.

By the way, this thread is longest discussion of the capacity of a simple 45kVA transformer I have EVER witnessed!!!

PS: Good old Google, took only a few seconds. The scary thing is, it WASN'T in this forum, but it WASN'T that long ago! Brain... getting... fuzzy,,,,
http://www.electriciantalk.com/f2/120-208-240-480-a-60157/#post1116694

 

[don_resqcapt19]

That's Ok, you probably still call them "PT"s too.:jawdrop:

Try putting 120/208V on a set of plans; I'm going to bid it as a single phase system, then CO the heck out of you and laugh every time I cash the check. :thumbsup:

I don't draw plans, that is the engineers job

I have seen "PT" used on some very recent drawings.

 

[don_resqcapt19]

That is what someone might presume, except why RFI? :? If it says 120/208V, then standards dictate that is a single phase system; ANSI C84 is quite clear. ...

The panel schedules would clearly show 3 phase panels, so if the voltage notation is 120/208, you should be sending an RFI.

If not the part in the specs that says, you have to install the most expensive equipment that the drawing could possibly indicate would apply.

 

[JRW 70]

Higher or Lower Voltage First

Higher or Lower Voltage First

With the exception of the 120/240 & 240/120,
I honestly can't think of any configs. we use that
don't put the higher voltage first (e.g. 12.4Y7.2kV
or 4160Y2400V for the distribution and for services
they are 480Y277, 480 Delta, 208Y120 etc.) I had to
search for what was mentioned above in the docs.
readily available to me and I just thought these ratings
were convention rather than standard based.

Try to learn something new everyday, so Thank You

*P.S. this is a very extensive thread for 45kVA transformer.
Hopefully the O.P. got the clarity they needed.

JR

 

[mivey]

Ooh, ooh, I can contribute to that tangent!

I once did a research paper in college on that exact subject. Turns out there IS an official meaning to the specific order in which the numbers are listed, and they ARE different. I can't for the life of me remember what the answer was right now, I drowned those brain cells in alcohol I guess. But I DID actually post this in here, or somewhere, a few years ago when a similar subject came up. I had dug up that old paper at that time, but it would be gone now because I have purged myself of old paperwork. If I can find my old post however, I'll link it or repeat it.

By the way, this thread is longest discussion of the capacity of a simple 45kVA transformer I have EVER witnessed!!!

PS: Good old Google, took only a few seconds. The scary thing is, it WASN'T in this forum, but it WASN'T that long ago! Brain... getting... fuzzy,,,,
http://www.electriciantalk.com/f2/120-208-240-480-a-60157/#post1116694

Don't forget 120/208Y.

Also,

B-N is not a valid voltage reference (it's floating) but typically measures out as 208V, so it is called "High Leg" delta

B-N (while normally not used for single-phase loads) is a valid voltage and does not float.

 

[mivey]

I have seen "PT" used on some very recent drawings.

PT (potential transformer) is an industry recognized term. I've been using it for decades, used it today, and will use it in the future as will most of the people in our industry. Most of what I see is "PT" for measuring and controls. For power transformers or for capacitive type metering and control transformers "VT" is more common. YMMV.