480v equipment at 430V

silencerman · Jan 16, 2020

I just got my electric service installed today. Due to PPL not doing high leg delta anymore my options were 4XXD or Y and 120/208Y. While i hated the idea of it i decided on 120/208 as it was the cheapest to install and i don't have to deal with phantom draw from transformers. The problem is that i have some 480 equipment and a 480 to 240 delta transformer to step up the voltage. The transformer is multi tap and has a tap for 503 on the high side which should give me 430 output when fed with 208. My question is will 430 be an acceptable voltage to run my 480 equipment at or should i look for a better suited transformer ASAP?

thermite · Jan 16, 2020

silencerman said:
I just got my electric service installed today. Due to PPL not doing high leg delta anymore my options were 4XXD or Y and 120/208Y. While i hated the idea of it i decided on 120/208 as it was the cheapest to install and i don't have to deal with phantom draw from transformers. The problem is that i have some 480 equipment and a 480 to 240 delta transformer to step up the voltage. The transformer is multi tap and has a tap for 503 on the high side which should give me 430 output when fed with 208. My question is will 430 be an acceptable voltage to run my 480 equipment at or should i look for a better suited transformer ASAP?

Should be fine. Especially if your "nominal" 208 is actually a tad higher.

Measured that, have you?

silencerman · Jan 16, 2020

i want to say 216 but i only measured it to see that voltage was present.

thermite · Jan 16, 2020

silencerman said:
i want to say 216 but i only measured it to see that voltage was present.

Folks have been sayin' "208/416 Wye" for a lot more than the 50+ years since I last lived off it. During which time.. wall outlets had continued their long creep up from 110 to 115 to 120 to 130 rated. Split-phase has gone nominal 220, 230, 240, and my "actual" has been 245/246 for 30 years, this house, so 122-123 per leg.

"I was just curious" as to what PowerCo in Pennsyltucky was actually DELIVERING to yah off yer in-house "208" terminations.

Doubt you have a problem. Especially if your nominal 4XX V loads are not majority use, and not for long and heavily loaded hours, each go. Run wathca got. Temp measing is cheap. Goods run hot? THEN you can see to a boost rig.

Or to re-connecting motors for their lower voltage?

DDoug · Jan 16, 2020

thermite said:
wall outlets had continued their long creep up from 110 to 115 to 120 to 130 rated. Split-phase has gone nominal 220, 230, 240, and my "actual" has been 245/246 for 30 years, this house, so 122-123 per leg.

We got lots O-coal and natural gas here in Pennsylvania....Spin them turbines baby....

thermite · Jan 16, 2020

digger doug said:
We got lots O-coal and natural gas here in Pennsylvania....Spin them turbines baby....

World has only got what? 11 years left before it ends?
Guess I'm gittin' to old to live ennyway per "AOC plus 3".

Why.. I'm so dam old I can even remember a time when John Llewellyn Lewis walked tall. Who'd ha' thunk a United Mine Workers giant would be a Republican? But even so, Democrats could still do grocery-store arithmetic!

Hard to believe it NOW. But there actually WAS such an era!

DDoug · Jan 16, 2020

"Locate your business in Pennsylvania, where you get more voltage for your money !
Next year, we are moving the frequency up to 90 hz.
Watch your productivity soar !"....

Jraef · Jan 16, 2020

480V utilization equipment is made for 460V to allow for voltage drop from the service point to the motor, then is +-10%, so 460-46 = 414V as the absolute minimum that a 460V motor can receive and perform within spec. But that doesn't mean it will not run hotter than normal, it will, so you can expect shorter life from your motors (heat x time = failure). But is that going to be measured in weeks or months? Probably not, more like a few less years, unless your motors are already old and frail.

thermite · Jan 16, 2020

Jraef said:
480V utilization equipment is made for 460V to allow for voltage drop from the service point to the motor, then is +-10%, so 460-46 = 414V as the absolute minimum that a 460V motor can receive and perform within spec. But that doesn't mean it will not run hotter than normal, it will, so you can expect shorter life from your motors (heat x time = failure). But is that going to be measured in weeks or months? Probably not, more like a few less years, unless your motors are already old and frail.

"Remains to be seen" what the service he has and the transformer he has actually DELIVER. My guess is it could as easily BE around 440 and a bit as the 'rithmetic of 430 V.

If not? A cheaper fix than even buck/boost or a different transformer?

Cheap supplementary fans right at each potentially problematic motor.

Or simpler and cheaper yet? Staged use so there is a cooling-off period between any heavy loads and/or any sustained use does not involve "heavy" loads.

No "show-stoppers" here, IOW.

"Awareness" of a POTENTIAL problem - exhibited in advance, as he has already done, plus reasonable caution as to observing how it works out in actual use, going forward, should do just fine.

SomeoneSomewhere · Jan 18, 2020

Most 230V motors have a 'usable at 208V' rating from what I can see. I imagine doubling this to 416V would be about right for a 460V motor.

You lose a little available power with the lower voltage, but if it's a user-fed tool like a lathe, saw, or drill press, just load it that few percent less. Set the overloads right and worst case you trip them.

It's possibly a different story for pumps/fans where you can't readily change the amount of load without changing the impellers.

/not a US sparky...

silencerman · Jan 19, 2020

i measured the voltage at one of my 220 plugs and got 213V if my calculations are correct using the 503 tap on my transformer i should get 446v out, Based on what you all have said i should be golden. thank you!

TDegenhart · Jan 20, 2020

Another option not mentioned is the use of buck/boost transformers. These can allow you modify the buck or boost the voltage in 16-32 volt range. They are not big transformers since they are rated at the buck/boost voltage times the current. Example, boost a 430 voltage to 462 at 30 amp. Boost voltage is 32, current is 30. KVA required is 1.0

Tom

Jraef · Jan 21, 2020

silencerman said:
i measured the voltage at one of my 220 plugs and got 213V if my calculations are correct using the 503 tap on my transformer i should get 446v out, Based on what you all have said i should be golden. thank you!

What you measure with no load on it is not as important as what it is going to be under load.

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