mbrooke
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Magnetizing inrush
- Thread starter mbrooke
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Your looking at K times ONAN vs K times ONAF I assume to fuse to your damage curve...
I believe normally ONAN is used. That’s what we use on our couple that’s left with fuses.
Will your transformer be ONAN most of the time (ours are 99% of the time)? If you forcing something right out of the gate you need a bigger XF.
We have one that sees above ONAN loading quite a bit. It’s being changed in 2020 for a larger unit.
I believe normally ONAN is used. That’s what we use on our couple that’s left with fuses.
Will your transformer be ONAN most of the time (ours are 99% of the time)? If you forcing something right out of the gate you need a bigger XF.
We have one that sees above ONAN loading quite a bit. It’s being changed in 2020 for a larger unit.
mbrooke
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Yes, to the damage curve and to make sure inrush will not blow the primary fuse.
Thus I interpret it like this:
40/50/60MVA
40MVA for inrush, while 60MVA is the peak current the trafo will draw.
mbrooke
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And so is the magnetizing for that S&C plot, correct? Sorry for all the doubt :ashamed1:
RumRunner
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With all the preeminence and the all- knowing omnipotence of Mr. Google, that should remove all your doubts.
The answers that you expect all come from the same source. It's just a matter of who is faster on the mouse click.
The miracle of the web. "Cut and paste" expertise is all you need.. . .it's a no-brainer.
At this stage of my journey--nothing amazes me anymore.
(Take note of my emoje--it's not an error.)
I don’t really agree with the cold load pickup inrush plots. I can see why the program plots them that way, but I don’t think it’s reality...
during an extended outage, there are more devices opened that the circuit reclosers or breakers at the station.
we energize the transformer first with nothing else closed.
we give the XF about two or three minutes and IF the line is clear to the first set of breakers we will energize the circuits one at a time, with some time in between.
From there loads normally have a chance to stabilize before additional lines are cleared and energized..
we also have a cold load pickup setting on the relays..
so tell me, why do you want to fuse a 40MVA XF? With a 751A at about $1200 with all kinds of protection and a 787 at $2200 for back up and additional 87 protection, why not spend the money, get a breaker and give your XF some real protection?
fuses are for assets you aren’t too overly concerned with... like pole transformers and wire...
not a 40MVA XF that is around 1.5 million...
mbrooke
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With all the preeminence and the all- knowing omnipotence of Mr. Google, that should remove all your doubts.
The answers that you expect all come from the same source. It's just a matter of who is faster on the mouse click.
The miracle of the web. "Cut and paste" expertise is all you need.. . .it's a no-brainer.
At this stage of my journey--nothing amazes me anymore.
(Take note of my emoje--it's not an error.)
Mr. Google can be wrong. I never trust the net, and I doubt Google knows what S&C is thinking. An actual human, like that on Mike Holts is on orders of magnitude more reliable. :happyyes:
mbrooke
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I agree. But picture hot load inrush during the summer- sub-transmission line trips out and then re-closes 5 seconds latter on peak sine wave, residual magnetism in the transformer core and a hundred compressors stalled out. For a few seconds I'd wager a bet loading that of or worse than cold load inrush.
Good read:
https://www.nerc.com/comm/PC/LoadModelingTaskForceDL/NERC LMTF presention- NGRID - Jan 2016.pdf
Yup, especially if you dealing with electric heat. Loose that thermostatic diversity in 30* whether and the substation basically is closing into a fault.
Who said its going to be 40MVA in practice?
But to answer your question cost. You also need a DTT signal in case of stuck breaker.How many newer transformer fail though? Most go 60 years without every getting a lock-out relay to trip or a primary fuse to blow.
mbrooke
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I'm sure we've all seen this well known PDF, but page 7 (210-110) goes into the details FWIW:
https://www.sandc.com/globalassets/...on-bulletin-210-110.pdf?dt=637127977071286791
RumRunner
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The profusion of YouTube videos/images cheapens the intelligent intent of messages. . . especially when loaded with MINUTIAE that aren't necessary.
I don't mind seeing a few once in a while, but not in every turn.
I remember in the early days of social media where forum members were limited in posting numerous amount of large and small pictures .
A few social media websites still do.
At the time, members were allowed only a certain amount of bytes for images to keep traffic from overtaxing the system which could otherwise be used for more important data.
Although, in today's internet infra-structure, the enormous amount of data that can be stored and delivered with little effort . . . we could still use the lesson of using bandwidth productively.
The whole internet system still has its limitations whether you want to believe it or not.
That’s why networks are aiming for the 5G.
In a more discreet and distinguishing characteristic that promote quality educational resource, there are still things that need to be kept for perusal only for those who really understand.
This applies not only to this website but also to many sites that try to impart valuable knowledge.
Viewing/posting photos would be at the lowest tier to achieve this. If you earn a living as a photo editor in Hollywood. . . it would be great.
That's not trying to stifle the learning process. Show-and-tell is still a part of this process. You see it in Kindergarten
Being able to discriminate between usefulness and uselessness is a sign of good taste.
mbrooke
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Humbly I somewhat disagree. I like pictures- and by far the most real world stuff I've seen on YouTube. But yes, there is stuff which is nonsense.
But also keep in mind, you have factual sounding information that is complete fallacy setting you astray on a foundational basis and keep leading you further away because the fake information simply builds off the false information. It makes sense knowing nothing, but in reality its not reality.
But as someone once said: with the internet smart people get smarter while dumb people get dumber. Not saying that about anyone here, just the human race as a whole.
But also keep in mind, you have factual sounding information that is complete fallacy setting you astray on a foundational basis and keep leading you further away because the fake information simply builds off the false information. It makes sense knowing nothing, but in reality its not reality.
But as someone once said: with the internet smart people get smarter while dumb people get dumber. Not saying that about anyone here, just the human race as a whole.
RumRunner
Senior Member
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Mr. Google can be wrong. I never trust the net, and I doubt Google knows what S&C is thinking. An actual human, like that on Mike Holts is on orders of magnitude more reliable.
………………
Where do you think these websites store their data for user retrieval?
They hire website designers to create pages so users can find them thru search engines like GOOGLE.
And when you are looking for something (anything at all) Mr GOOGLE is there to find it for you. That’s why it’s called search engine.
Without this effort you won’t see their website pages.
My daughter is a website designer working for the Disney Corporation. She is familiar about how this system work.
Not necessarily that I know all of what she knows, but she does give me some useful ideas.
Website pages of companies are what make us able to read about their products. . . and this is how this web designers make money.
They are in there (website pages) for promoting their business,
If people don’t know anything about transformers or power distribution they won’t even bat an eye to open any of their published pages.
…………..
Humbly I somewhat disagree. I like pictures- and by far the most real world stuff I've seen on YouTube. But yes, there is stuff which is nonsense.
But also keep in mind, you have factual sounding information that is complete fallacy setting you astray on a foundational basis and keep leading you further away because the fake information simply builds off the false information. It makes sense knowing nothing, but in reality its not reality.
………..
Facts that are presented do not fall under fallacy classification. Only speculations and unproven hypotheses.
Factual information is verifiable.
Being verifiable cannot simply be considered veritable by representing it in pictures in this day and age.
It’s no longer following the old proverb that: “pictures are worth a thousand words.”
It only takes one fake picture to discredit every possible real pictures that would follow.
It’s more like: “once a jackass, always a jackass” (not an expletive, but refers to real sly animal).
No amount of redemption could undo this despicable reputation.
That’s why I hardly pay attention to those YOUTUBE videos. As I have said before: YOUTUBE is hazardous to your mental health.
Psychological studies show die-hard people who spend too much time on YOUTUBE become depressed. They lose the dichotomy between real and unreal. The cause of their depression.
..............
But as someone once said: with the internet smart people get smarter while dumb people get dumber. Not saying that about anyone here, just the human race as a whole.
................
Smart people are the ones who are capable of twisting the truth. . . dumb people remain dumb because they never had the faculties to determine real from fake.
………………
Where do you think these websites store their data for user retrieval?
They hire website designers to create pages so users can find them thru search engines like GOOGLE.
And when you are looking for something (anything at all) Mr GOOGLE is there to find it for you. That’s why it’s called search engine.
Without this effort you won’t see their website pages.
My daughter is a website designer working for the Disney Corporation. She is familiar about how this system work.
Not necessarily that I know all of what she knows, but she does give me some useful ideas.
Website pages of companies are what make us able to read about their products. . . and this is how this web designers make money.
They are in there (website pages) for promoting their business,
If people don’t know anything about transformers or power distribution they won’t even bat an eye to open any of their published pages.
…………..
Humbly I somewhat disagree. I like pictures- and by far the most real world stuff I've seen on YouTube. But yes, there is stuff which is nonsense.
But also keep in mind, you have factual sounding information that is complete fallacy setting you astray on a foundational basis and keep leading you further away because the fake information simply builds off the false information. It makes sense knowing nothing, but in reality its not reality.
………..
Facts that are presented do not fall under fallacy classification. Only speculations and unproven hypotheses.
Factual information is verifiable.
Being verifiable cannot simply be considered veritable by representing it in pictures in this day and age.
It’s no longer following the old proverb that: “pictures are worth a thousand words.”
It only takes one fake picture to discredit every possible real pictures that would follow.
It’s more like: “once a jackass, always a jackass” (not an expletive, but refers to real sly animal).
No amount of redemption could undo this despicable reputation.
That’s why I hardly pay attention to those YOUTUBE videos. As I have said before: YOUTUBE is hazardous to your mental health.
Psychological studies show die-hard people who spend too much time on YOUTUBE become depressed. They lose the dichotomy between real and unreal. The cause of their depression.
..............
But as someone once said: with the internet smart people get smarter while dumb people get dumber. Not saying that about anyone here, just the human race as a whole.
................
Smart people are the ones who are capable of twisting the truth. . . dumb people remain dumb because they never had the faculties to determine real from fake.
mbrooke
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I agree- but would you rather use Disney's site for information about their services rather than some random person on say reddit.
Verifiable with what and against what? Do you have any idea how many "expert" and "pro" websites exist to verify joe DIY's claim that ground rods protect people from shock? Long drawn out lecture that the earth is a sink and a few extra electrons are just adding drops of water to the ocean so the earth will never loose its negative charge potential?
Why should I trust some old senile guy from Florida who made a YouTube video with folding tables and dyed bed sheets in what looks like his basement patronizingly shouting "grounding is not bonding, bonding is not grounding"? I mean sure he has a businesses, but with an objective to sell his books which seem to go against common knowledge which is clearly proven wrong by a few mouse clicks on Google.
Of course, this is in no way taking a swipe at Mike, rather how his videos and books could be viewed and has come up on DIY sites years back.
I have to disagree. Not every YouTube video is made a trolls or conspiracy theorists. There are tons of legit people like engineering students sharing their knowledge with the world. And what better way to show a real time event like a glowing busbar then recording it?
Smart people with evil intentions yes- but just as tragic dumb people in positions of power. When authority says something parts of our brain that deal with logic and reasoning shut down. A doctor could say something absolutely untrue, but you would believe it solely based on his credentials. Not that a doctor would deliberately lie, and that applies to those posting here. Smart people on here with good intentions
RumRunner
Senior Member
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- SCV Ca, USA
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- Retired EE
I agree- but would you rather use Disney's site for information about their services rather than some random person on say reddit.
Verifiable with what and against what? Do you have any idea how many "expert" and "pro" websites exist to verify joe DIY's claim that ground rods protect people from shock? Long drawn out lecture that the earth is a sink and a few extra electrons are just adding drops of water to the ocean so the earth will never loose its negative charge potential?
Why should I trust some old senile guy from Florida who made a YouTube video with folding tables and dyed bed sheets in what looks like his basement patronizingly shouting "grounding is not bonding, bonding is not grounding"? I mean sure he has a businesses, but with an objective to sell his books which seem to go against common knowledge which is clearly proven wrong by a few mouse clicks on Google.
Of course, this is in no way taking a swipe at Mike, rather how his videos and books could be viewed and has come up on DIY sites years back.
I have to disagree. Not every YouTube video is made a trolls or conspiracy theorists. There are tons of legit people like engineering students sharing their knowledge with the world. And what better way to show a real time event like a glowing busbar then recording it?
Smart people with evil intentions yes- but just as tragic dumb people in positions of power. When authority says something parts of our brain that deal with logic and reasoning shut down. A doctor could say something absolutely untrue, but you would believe it solely based on his credentials. Not that a doctor would deliberately lie, and that applies to those posting here. Smart people on here with good intentions
Nothing in your protracted missive makes way for an intelligent discussion. It's no different from your puerile videos.
I have no qualms about instructional MH videos. They are instructional as the word goes, but your videos are just a waste of bandwidth.
No wonder forum members complain about traffic slow down.
You are hogging the speed.
And please don't start the argument about syllogism (fallacy).
You still need to know what the animal is.
mbrooke
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:blink:
There shouldn't be a video in this thread (at least I'm hoping something inappropriate didn't inadvertently get linked)- the screen shot is from S&C's coordinate. In no way am I doubting Hv&Lv or you. Just expressing my opinion that S&C should give more information on how they came to the values that they did. Honestly, I think its a generic off the shelf from a 10MVA unit with a considerable multiplier.
mbrooke
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JoeStillman
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Inrush is a function of impedance. Actual impedance doesn't change with cooling ratings, but per-unit impedance does. The ratings on the XFMR nameplate are supposed to be per-unit on the ONAN-rated kVA base. When you plot the inrush point on a TCC, use the ONAN kVA rating and impedance.
mbrooke
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Will do so. It looks like S&C is also basing it off the base rating, but how it got those numbers... I can only guess.
sgtsparky
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I was taught that inrush normally around 6X on motors was because the magnetic fields have not formed yet so DC resistance value is used until the fields are fully developed then the impedance limits the current, this was better explained with motors but transformers have the similar characteristics I would agree with the comments that a proper breaker should be used as that is a expensive xformer 40mva of course this is without a load, any time I lose one of my mains I shut down the 6 feeders then bring things up one at a time watching the demand meter on my main but my transformers are much smaller only 500kva (I do find my transformers handle cold temps better as someone else also commented).
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