High amp buck-boost transformer

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lowvoltman

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I'm looking to transform 480v single phase down to 440v(or close to it) with a load of 250 amps. 480 is too far off, it's got to be as close to 440 as I can get. Any suggestions? Does anyone make a buck-boost that size? Thanks!
 
lowvoltman said:
I'm looking to transform 480v single phase down to 440v(or close to it) with a load of 250 amps. 480 is too far off, it's got to be as close to 440 as I can get. Any suggestions? Does anyone make a buck-boost that size? Thanks!
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The are custom transformer manufacturers that would make one for you. But, remember that transformers are not regulators so if the supply voltage varies the output voltage will vary.
Are you sure that you have a 480v supply as 480v is a nominal voltage? It is of my opinion that it is not unusual for it to be less than that. As I recall standard B/B transformer I believe will buck 32v so 440+32=-472v and you're not splitting hairs. If you can establish as such you may find a standard design B/B transformer available.
You didn't say if it was 1ph or 3ph but assuming it's a 3ph wye I believe (3) 3kva (or 5kva) B/B transformers may be able to do it for you. 3kva may be on the edge.
 
lowvoltman said:
I'm looking to transform 480v single phase down to 440v(or close to it) with a load of 250 amps. 480 is too far off, it's got to be as close to 440 as I can get. Any suggestions? Does anyone make a buck-boost that size? Thanks!
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I frequently see similar questions about buck-boost transformers posed here.
Maybe your question is whether anyone makes such a transformer as a standard product that you can buy off the shelf.
I don't know but I'd guess probably not.
That said, I see no technical difficulty in getting one made to your specification. That's what I would do and have done for non standard arrangements.
But I'm on the other side of the pond and routinely require special build.
 
I think the largest I have seen offered is 10kva, so 110kva is going to be a per order if you can find one of the manufactures that will make it.

a 32 volt will give you 448 volts, and a 48 volt will give you 432 volts, take your pick, if you have to have it made it might be possible to get a 40 volt one made?

what is the load are we talking about if I may ask?

I can not imagine the size of the conductors on the 32 volt side of that transformer @ 110kva

they will be sized to 3437.5 amps.
 
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480->440 1ph autoxfmr

480->440 1ph autoxfmr

yes, these are available. this would not be a very expensive device. as example, we build custom transformers like this daily with std 3 week delivery.
 
hillbilly1 said:
May be cheaper to go with an actual step down transformer, may even be somewhat easier to get.
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I can't see a 110kva step down transformer being cheaper, I might be wrong, but it take a lot less winding to buck or boost, the only problem I see is the 110kva rating of the 32 volt secondaries as stated above? maybe buss bar connections would be the way to go?
 
Wayne, why would the BB transformer need to be rated at 110KVA? You size the transformer base on the secondary voltage not the total voltage. 32 volt @ 250 amps is 8KVA.
 
buck boost size

buck boost size

I believe 110 kva would be appropriate for a standard step down transformer. A buck boost of the 15 kva variety should suffice for this application. I was trying to find an off the shelf one but 10 kva is the biggest I've found. Thanks
 
curt swartz said:
Wayne, why would the BB transformer need to be rated at 110KVA? You size the transformer base on the secondary voltage not the total voltage. 32 volt @ 250 amps is 8KVA.
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You are very correct, I have no idea why I was thinking the BB transformer had to be rated the full load:ashamed1:, so yes a 8kva is right on the money and is an off shelf item.

Whoops:blink:
 
lowvoltman said:
I believe 110 kva would be appropriate for a standard step down transformer. A buck boost of the 15 kva variety should suffice for this application. I was trying to find an off the shelf one but 10 kva is the biggest I've found. Thanks
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Yes, I agree. I'm seeing 7.5 kva at about 160a. I think it would be best to order one from a custom transformer manufacturer which should be a 4-6 week item at most. Quite often you may find a standard design in the catalog but it may likely be a non stock item anyway.
Remember that a step down (isolating type) transformer must carry the full KVA of the load Vs. the B/B that only needs the KVA required to make the voltage change.
 
templdl said:
I think it would be best to order one from a custom transformer manufacturer which should be a 4-6 week item at most. Quite often you may find a standard design in the catalog but it may likely be a non stock item anyway.
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as a custom transformer supplier, I can tell you all that a custom transformer most often costs LESS than the closest "standard" transformer and typically have lead times at least from us of 3 weeks, with 2 weeks not uncommon & 1 week most of the time when required.....
 
hurk27 said:
After searching some, I find that bucking a 480 volt is only offered in a 24/48 volt secondaries, which will push the KVA to about 12, and will be special order:(
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I know that the one of the companies that I workerd for had both 12/24 and 16/32 B/B transformers.
A customer transformer manufacturer may dial that in a bit closer depending the winding ratio that is possible.
 
mike_kilroy said:
as a custom transformer supplier, I can tell you all that a custom transformer most often costs LESS than the closest "standard" transformer and typically have lead times at least from us of 3 weeks, with 2 weeks not uncommon & 1 week most of the time when required.....
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Normally cost much less providing you don't need isolation because only the kva need to adjust the voltage is required.
A 1-2 week lead tome may come at a premium $$$. I worked at custom trasfomrer manufacture and it is fairly difficult to get a custom designed transformer through engineering, unless they have an existing design, and into manufacturing having to fabricate and powder coat the parts, stamp out the core materials, wind the coils, assemble the core and coils and initial test, and quote often these are TENV NEMA3r enclosed transformers that are filled with epoxy and sand which has to set and final testing. As such less than 2 weeks is pushing it.
 
with today's transformer design software most custom shops, like ours, uses, this is an easy part and takes about 10 minutes to design a custom unit like this one. Most custom xfmr mfgrs for this size unit do not stamp their own steel; it is MUCH cheaper to buy it from a steel scrap supplier who also stamps it or sends it to a stamper for you. With good stock of std E-I & stack core steel, there is seldom any delay to get material. Likewise std cu and al is stocked so seldom any wait for it. Longest time today is dip and oven time. there is seldom any powder coating of parts; if so, the local partner panel shop down the road does it while we build the transformer, so being done in parallel rather than sequentially, again no delay. So 1 week is usually no problem although we do try to get a premium to cover putting it before other customers who were there first. But to get one, one has to ask for a quote first. :)
 
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