75 kva transformer Primary and Secondary feed

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electricbird

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electrician
Tasked with hooking up a still, (istill), from the Netherlands. Nameplate says 3 x400vac, fla:83a ,60hz, supply fuse 90a, Phase: 3 phase +pe, 4 wire...Apparently European 3 phase is 400 volt. We have 240 3 phase here, ( line to line, with one high leg) They recommend 75 kva transformer 240 to 400, ( we are looking to get one from Maddox 240v Delta -400y 231 step up transformer. Calculations show 180 amps primary, 108 secondary. Issue: We have a 200 amp 3 phase panel, which I doubt you can find a 180 amp breaker for. 100 amp will not do, right?? Use a ocpd for the secondary side right?? Will we have to upgrade service/ panel for a 180 a breaker to feed transformer? I have seen other discussions about feeding with a 100 amp, but that was with higher voltage,(460?) I appreciate thoughts and expertise
 
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petersonra

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75kva at 240 volts is over 175 amps on the primary side. I would not be using less than a 400 amp breaker to avoid nuisance trips. I think you need to find a higher rated feeder to pull this from.

I would want a 100 amp ocpd on the still itself which could also serve as transformer secondary and secondary conductor protection.
 
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jim dungar

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With a primary current of 180A, the NEC would allow a circuit breaker of up to 225A so you can definitely use a standard 200Abreaker. However I agree it probably needs to be bigger.
If you chose to go to a breaker larger than 225A you will need to provide secondary side protection of not more than 135A (no up sizing allowed).
 
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hillbilly1

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Does the panel have sub feed lug capability? Could use a sub feed lug kit to a 200 amp fusible disconnect or breaker enclosure, and use the appropriate ocp.
 
kwired

kwired

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Location
NE Nebraska
electricbird said:
Tasked with hooking up a still, (istill), from the Netherlands. Nameplate says 3 x400vac, fla:83a ,60hz, supply fuse 90a, Phase: 3 phase +pe, 4 wire...Apparently European 3 phase is 400 volt. We have 240 3 phase here, ( line to line, with one high leg) They recommend 75 kva transformer 240 to 400, ( we are looking to get one from Maddox 240v Delta -400y 231 step up transformer. Calculations show 180 amps primary, 108 secondary. Issue: We have a 200 amp 3 phase panel, which I doubt you can find a 180 amp breaker for. 100 amp will not do, right?? Use a ocpd for the secondary side right?? Will we have to upgrade service/ panel for a 180 a breaker to feed transformer? I have seen other discussions about feeding with a 100 amp, but that was with higher voltage,(460?) I appreciate thoughts and expertise
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Depending on what you have you might be able to get breakers that utilize two spaces per pole, they will at very least be in the standard 150, 175, 200 and 225 amp ratings though. Does your 200 amp panel have the capacity to handle this added load, outside of the possible inrush current issues?
 
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petersonra

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hillbilly1 said:
Does the panel have sub feed lug capability? Could use a sub feed lug kit to a 200 amp fusible disconnect or breaker enclosure, and use the appropriate ocp.
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If the panel has a 200 A main, why would one want an external 200 A OCPD?

Unfortunately with a transformer of that size chances are you are risking nuisance trips of the main regardless of any downstream OCPD.
 
Besoeker3

Besoeker3

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UK
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Retired Electrical Engineer
electricbird said:
Tasked with hooking up a still, (istill), from the Netherlands. Nameplate says 3 x400vac, fla:83a ,60hz, supply fuse 90a, Phase: 3 phase +pe, 4 wire...Apparently European 3 phase is 400 volt. We have 240 3 phase here, ( line to line, with one high leg) They recommend 75 kva transformer 240 to 400, ( we are looking to get one from Maddox 240v Delta -400y 231 step up transformer. Calculations show 180 amps primary, 108 secondary. Issue: We have a 200 amp 3 phase panel, which I doubt you can find a 180 amp breaker for. 100 amp will not do, right?? Use a ocpd for the secondary side right?? Will we have to upgrade service/ panel for a 180 a breaker to feed transformer? I have seen other discussions about feeding with a 100 amp, but that was with higher voltage,(460?) I appreciate thoughts and expertise
Click to expand...
If it's from Europe it will be 50Hz. f you want to import to USA you need to consider that - especially where motors are involved.
 
kwired

kwired

Electron manager
Location
NE Nebraska
petersonra said:
would a still have any motors?
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If it includes any pumps, yes and that could be a problem especially if they are induction motors as base speed will be higher with higher frequency and that increase in speed likely loads the pump more than what the design was for.
 
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petersonra

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Northern illinois
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engineer
kwired said:
If it includes any pumps, yes and that could be a problem especially if they are induction motors as base speed will be higher with higher frequency and that increase in speed likely loads the pump more than what the design was for.
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If it has motors, there might be a need to get some VFDs for them. However, since the OP seemed to indicate the transformer suggestion came from the manufacturer, one would hope they have already took motors (if any) into account.
 
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hillbilly1

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Location
North Georgia mountains
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Owner/electrical contractor
petersonra said:
If the panel has a 200 A main, why would one want an external 200 A OCPD?

Unfortunately with a transformer of that size chances are you are risking nuisance trips of the main regardless of any downstream OCPD.
Click to expand...
So you can turn the transformer off without affecting the loads already in the panel.
 
kwired

kwired

Electron manager
Location
NE Nebraska
petersonra said:
If it has motors, there might be a need to get some VFDs for them. However, since the OP seemed to indicate the transformer suggestion came from the manufacturer, one would hope they have already took motors (if any) into account.
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Yes, if they are VFD driven, DC, or other non direct connected induction motor types they may be fine.
 
kwired

kwired

Electron manager
Location
NE Nebraska
hillbilly1 said:
Transformer goes down, or needs preventative maintenance, do you want to take everything else down with it?
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If coming off subfeed lugs, you can always add a disconnect to be able to isolate it. If not needing reduced OCPD can even use non fused disconnect.
 
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