- Location
- Massachusetts
I posted it already.
But OCP is not really the topic I was talking about. I was very specifically talking about the kVA load on the auto transformer itself. Not the kVA load on the OCP nor the kVA drawn by the load.
208v to 240v Buck Boost Transformer Calculations
- Thread starter Jmays
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I posted it already.
But OCP is not really the topic I was talking about. I was very specifically talking about the kVA load on the auto transformer itself. Not the kVA load on the OCP nor the kVA drawn by the load.
mivey
Senior Member
It is an exercise in you not admitting you were wrong. Its that simple.
Nothing to comment on as it has nothing that refutes Iwire's post.
As for the content, there is nothing new or revealing. I know how transformers work and so do many others here. If we were trying to teach others we could go into more detail.
But you are just beating a dead horse to make it sound like you were right and Iwire was wrong.
You were wrong. Get over it and move on.
mivey
Senior Member
That is not what Iwire said.
Build as many strawmen as you want but it won't change the fact that you were wrong. I know it. Iwire knows it. Others here know it. If you really don't know it by now there is not much else to add.
mivey
Senior Member
I know what he said. I know what he meant. You do not. You are wrong.
What you say and what he meant are all wrong. You both have confused the OP.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
I agree with your observation of what Sahib is doing, but I think he has a different basis for his misunderstanding.
As I see it, he is unwilling to admit to his part in a language misunderstanding, rather than trying to correct it. Rather than try to figure out why we are not communicating, Sahib is telling us that we don't understand the physics of transformers.
I believe that he is counting as part of the transformer the wires leading from the supply and the wires leading to the load... and counting power delivered directly from the source to the load as part of the transformer rating. In his language, if the transformer as configured is delivering 15kVA, then it is a '15kVA autotransformer'.
All the rest of us are only counting the windings and core, and saying that any power directly delivered by the source to the load is _not_ part of the transformer rating.
Imagine I sell you a box called a 'voltage raising unit' (not specified to be a transformer). It is rated to go from 208V input to 240V output, with 47A rated output. It has 2 input terminals that you connect to a 208V supply, and it has 2 output terminals.
What would you call the VA rating of this 'voltage raising unit' box?
Now when you open the box you find that internally it has a 240V to 32V transformer connected in a voltage boost configuration. This _component_ of the voltage raising box has a 1.5kVA rating.
I will affirm that a _transformer_ consists of the coils and core, and that any loading on that transformer is from voltage applied across the coil terminals and current flowing through the coils. I do not count power going 'around' the transformer as part of the transformer rating.
-Jon
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Honestly, I am of the opinion that the basis of many of his posts is to sow confusion/dissention and I am at a loss as to the reason why.
I don't know (care) if you are being stubborn or just don't 'get' it
but matters not, your understanding is incorrect
no big deal, you'll get over it
no use explaining it
it takes the same knowledge to generate the correct answer as it does to SEE it when others present it to you
Honestly, I am of the opinion that the basis of many of his posts is to sow confusion/dissention and I am at a loss as to the reason why.
as the fn new guy I tend to agree with your observation
the rooftop sizing issue is an example
Honestly, I am of the opinion that the basis of many of his posts is to sow confusion/dissention
You should have acted to clear confusion/dissent as a moderator because you are supposed to possess greater knowledge/experience instead of behaving like
Exactly. The example 3.2 of my earlier post#73 clearly shows how to calculate the KVA rating of the autotransformer from the 2 winding transformer which is in line with what I am trying to make you understand that inductive component of power transferred alone does not constitute the rating of the autotransformer.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Well you won't communicate that effectively by telling some very smart people that they don't understand how transformers work or laughing at them. Instead you should be agreeing on the physics and showing examples of where the _wording_ is used differently.
In the example you referenced, where a 10kVA transformer was used in a boost configuration, the example shows a 110kVA load being served, and we would all agree with this calculation.
However the document itself does _not_ say that the transformer has a 110kVA power rating. The exact words from the document are 'the apparent-power rating when connected as an autotransformer.'. Not 'power rating' but 'apparent-power rating'.
I bet that if you called the authors and asked, they would say that the transformer rating remains 10kVA, but that the ability of the transformer to serve a load is similar to that of a 110kVA isolation transformer, thus the use of the term 'apparent-power rating'.
-Jon
mivey
Senior Member
Jon,
You will find both "apparent rating" and "rating" used by credible sources for the 110 kVA. You will not find them saying the actual load on the transformer is more than 10 kVA, which was Iwire's point.
WRONG wrong. Once an AT is formed, there is no separate isolation Tr in it. It transfers power both by induction and by conduction. iwire mistake is he thinks power tranfer by conduction is independent of AT. It is not.
kwired
Electron manager
- Location
- NE Nebraska
Transfer and transform are not the same thing. Net load is transferred through a portion of the transformer. Only a portion of the net load is transformed within the transformer with an autotransformer. An isolation transformer does transfer and transform 100% of the load.
The circuit conductors transfer the load as well.
mivey
Senior Member
Your mistake is thinking that is what Iwire said. Another strawman to add to your collection.
You should note what it means to transform energy.
I don't you want to or are able to understand Iwire's point.
mivey
Senior Member
Post missed in passing but that is one thing Sahib doesn't appear to get or acknowledge.
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