480 volt to 400 volt transformer

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steve66

Senior Member
Location
Illinois
Occupation
Engineer
Does anyone make a transformer with a 400 volt secondary? Or can I get a custom wound transformer to provide this voltage?


I need it to power a piece of equipment that is coming from Europe. It needs to be rated for a continuous load of 300 KVA.
 

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
You can get any kind of custom wound transformer if you can wait and pay.:)
And depending on the details (delta v. wye, etc.) you may be able use a buck transformer.
 
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jim dungar

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Staff member
Location
Wisconsin
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PE (Retired) - Power Systems
Does anyone make a transformer with a 400 volt secondary? Or can I get a custom wound transformer to provide this voltage?


I need it to power a piece of equipment that is coming from Europe. It needs to be rated for a continuous load of 300 KVA.

What primary voltage?

Do you also need to deal with the difference in frequency?
400V @50Hz performs similar to 480V @60Hz, when it comes to things with magnetic coupling like motors and transformers. This means 400V @60Hz might be detrimental to your equipment.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
What primary voltage?

Do you also need to deal with the difference in frequency?
400V @50Hz performs similar to 480V @60Hz, when it comes to things with magnetic coupling like motors and transformers. This means 400V @60Hz might be detrimental to your equipment.

480 volts primary. The vendor has stated the power requirement as 400 volts at 60 hz, so I believe they have already decided the difference in frequency isn't a problem. They have actually divided the equipment's power requirement into 2 different sources: 480 V, 60 hz, 200 KVA, and 400 V, 60 hz, 300 KVA.
 

Electric-Light

Senior Member
What primary voltage?

Do you also need to deal with the difference in frequency?
400V @50Hz performs similar to 480V @60Hz, when it comes to things with magnetic coupling like motors and transformers. This means 400V @60Hz might be detrimental to your equipment.


Yep. Matching the V/Hz ratio is important.
Without knowing what machine it is, I don't know what to expect.
Controls will advance one day in 20 hours when equipment rated at 50Hz is used on 60Hz.
Motors will spin at 120% the speed.
Centrifugal pumps do not handle incorrect speeds well.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
You can get any kind of custom wound transformer if you can wait and pay.:)

So is that something someone like Square D or Cutler Hammer can provide, or do I have to find a custom transformer fabricator?

And depending on the details (delta v. wye, etc.) you may be able use a buck transformer.

I think the voltage difference and KVA rating are too high to make a buck a good option.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
How about 416V?

Buy three each - 1ph, 100KVA 480/240. Connect the 480V primaries in delta, connect the 240V secondaries in Wye. This will give you 416V 3ph out.

Possibly there will be taps on the primaries. A -2.5% tap will take the output down to 406V

Might even be on a shelf

ice
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
How about 416V?

Buy three each - 1ph, 100KVA 480/240. Connect the 480V primaries in delta, connect the 240V secondaries in Wye. This will give you 416V 3ph out.

Possibly there will be taps on the primaries. A -2.5% tap will take the output down to 406V

Might even be on a shelf

ice

They ask for a 2% tolerance, and the utility is normally off by a little, so I don't think that quite gets me there.

3 single phase 480-240 volt transformers. Hook in wye and presto.

Do you mean connect them wye-wye? Or delta-wye? That's not quite 400 volts even.
 

Electric-Light

Senior Member
480 volts primary. The vendor has stated the power requirement as 400 volts at 60 hz, so I believe they have already decided the difference in frequency isn't a problem. They have actually divided the equipment's power requirement into 2 different sources: 480 V, 60 hz, 200 KVA, and 400 V, 60 hz, 300 KVA.

So, what does this machine do??
That doesn't even make sense. I think you got it backward. Equipment's kVA rating should not change much unless it is resistive.

Look at a water heater. You'll see something like:
4.5kW 240v
3.375kW 208v
(208/240)^2 = 0.75
In other words, electric water heaters operated on 208v is derated 25%.

(480/400)^2 = 1.44
1.44 * 200kW = 288kW

You can use a transformer intended to operate our 480v motors in Canaduh on their 600/347.
It's specifically rated to allow 480 to 380 use as well.
http://www.acmetransformer.com/en/t2a527181 It will be cheaper than a custom 480 to 400 one.

IEC voltage is now harmonized to 400/230
It's consolidated from 415/240, 400/230 and 380/220.
 
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templdl

Senior Member
Location
Wisconsin
So, what does this machine do??
That doesn't even make sense. I think you got it backward. Equipment's kVA rating should not change much unless it is resistive.

Look at a water heater. You'll see something like:
4.5kW 240v
3.375kW 208v
(208/240)^2 = 0.75
In other words, electric water heaters operated on 208v is derated 25%.

(480/400)^2 = 1.44
1.44 * 200kW = 288kW

You can use a transformer intended to operate our 480v motors in Canaduh on their 600/347.
It's specifically rated to allow 480 to 380 use as well.
http://www.acmetransformer.com/en/t2a527181 It will be cheaper than a custom 480 to 400 one.

IEC voltage is now harmonized to 400/230
It's consolidated from 415/240, 400/230 and 380/220.
Yes, you we could nbe able to come close to 400v with a 380v secondary by using the -(2) or (4) 2-1/2% FCBN taps that are most likely available on the 480v primary which you could use to raise the secondary voltage.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
They ask for a 2% tolerance, and the utility is normally off by a little, so I don't think that quite gets me there.

If the supplier is asking for a 2% tolerance on the 400V, then I think the first thing you need to establish is the tolerance on your 480V supply per utility tariff.

I think you will find that your utility will allow your service voltage to vary by +-5%.

If this is the case, then you may need more than just a transformer with the correct winding ratio.

-Jon
 

topgone

Senior Member
Do you mean connect them wye-wye? Or delta-wye? That's not quite 400 volts even.

IMO, your utilization voltage could go down to 460V and that's just the voltage needed to give you 400V, 3-phase from a banked 480/240V wired secondary in wye.
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
If the supplier is asking for a 2% tolerance on the 400V, then I think the first thing you need to establish is the tolerance on your 480V supply per utility tariff.

I think you will find that your utility will allow your service voltage to vary by +-5%.

If this is the case, then you may need more than just a transformer with the correct winding ratio.

-Jon

This is very true, and usually the system coming into the building will be on the +side of the nominal voltage. Per standard operating procedures the utility is not going to guarantee that.

Sounds like your best bet is to get a 3ph 480V input rectifier, and use an inverter to get the stable 400V output.

Somebody better check with manufacturer and determine if that tolerance is absolute, because, a 300KVA, 480V-400V system ain't gonna be cheap.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
So, what does this machine do??
That doesn't even make sense. I think you got it backward. Equipment's kVA rating should not change much unless it is resistive.

Look at a water heater. You'll see something like:
4.5kW 240v
3.375kW 208v
(208/240)^2 = 0.75
In other words, electric water heaters operated on 208v is derated 25%.

(480/400)^2 = 1.44
1.44 * 200kW = 288kW

You can use a transformer intended to operate our 480v motors in Canaduh on their 600/347.
It's specifically rated to allow 480 to 380 use as well.
http://www.acmetransformer.com/en/t2a527181 It will be cheaper than a custom 480 to 400 one.

IEC voltage is now harmonized to 400/230
It's consolidated from 415/240, 400/230 and 380/220.

I guess I didn't explain that very well - Its a 500 KVA machine. It needs both the 480V and the 400 volt supplies. It's not one or the other. So the manufacturer already knows it will be installed where only 480V is standard, and they have decided some of the power can be supplied directly at 480 volts, and some has to be 400 volts. They have also stated that 60 hz is fine for both supplies.
 

templdl

Senior Member
Location
Wisconsin
If the supplier is asking for a 2% tolerance on the 400V, then I think the first thing you need to establish is the tolerance on your 480V supply per utility tariff.

I think you will find that your utility will allow your service voltage to vary by +-5%.

If this is the case, then you may need more than just a transformer with the correct winding ratio.

-Jon
Also remember that a transformer is not a voltage regulator. The secondary voltage is dependent upon what the voltage is at the primary at any given point in time.
 
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