transformer

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hondastang

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Location
Duluth, MN
Hello. Question I have to wire up a transformer that's a 112.5kv 480v primary delta. The secondary side is 208/120 wye. I think they ordered the wrong one. Because they need 480v delta primary to 460v secondary. Can it still be done or do they have to get a different transformer. I do not have a lot of experience with this area. Can I get help Please. Thanks This forum is super nice
 

topgone

Senior Member
Hello. Question I have to wire up a transformer that's a 112.5kv 480v primary delta. The secondary side is 208/120 wye. I think they ordered the wrong one. Because they need 480v delta primary to 460v secondary. Can it still be done or do they have to get a different transformer. I do not have a lot of experience with this area. Can I get help Please. Thanks This forum is super nice

Maybe you meant 112.5 kVA, 480-208/120v transformer!
Still, why did "they" think there's a problem with having 480V supplying 460V equipment? (4% difference in voltage).
 

jbelectric777

Senior Member
Location
NJ/PA
I think they all go by a parameter like it could be 110,120,125,130 (20V difference) so maybe its the same with transformers. What about using the taps in the transformer? I agree the transformer is the right kind - check the taps inside the cover and see if there are tap points for your situation.
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
Hello. Question I have to wire up a transformer that's a 112.5kv 480v primary delta. The secondary side is 208/120 wye. I think they ordered the wrong one. Because they need 480v delta primary to 460v secondary. Can it still be done or do they have to get a different transformer. I do not have a lot of experience with this area. Can I get help Please. Thanks This forum is super nice

Check to see if they need to generate a neutral for some reason; 480-480Y/277V.

You can use the taps to reduce the voltage but most likely the equipment is rated 460V for operation on a 480V system.
 

hondastang

Member
Location
Duluth, MN
transformer

Hello again The reason for the 460 wye is the machine built across in Germany where they have the difference. I am getting information from company hooking up the machine. It a laser cutter.
 

topgone

Senior Member
Hello again The reason for the 460 wye is the machine built across in Germany where they have the difference. I am getting information from company hooking up the machine. It a laser cutter.

You said Germany but European standards have harmonized to 400V! If it is indeed 400V, then you can wire your 480/120 into an autotransformer bucking configuration.
figure_g.jpg
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Once again into the breech...

Don't install anything yet. Look at EXACTLY what they have first.

It's HIGHLY unlikely that anything from Germany would require 460V, I agree thst it's more likely 400V. But that would be 400V at 50Hz, not 60Hz. We have 60Hz. If you transform down to 400V, the difference in frequency might get you in trouble. AC induction motors that are not run from VFDs will run 20% faster but will produce 20% less running torque and 36% less accelerating torque, resulting in higher slip, more current with less work and a likelihood of burning up. If you just feed them 480V, the V/Hz ratio is exactly the same as 400V / 50Hz and they will deliver full torque, but still run 20% faster. All of that needs to be considered.

In addition, what they would use in Germany is 400Y230V, so any phase to neutral connections, such as might be used in control circuits and aux devices like single phase cooling fans, will be expecting to see 230V, not 277V. So they may need to be separated and fed appropriately.

And then again, if the machine contains power electronics such as VFDs, DC drives, servos and power supplies, they all may not give a rat's butt what you feed them.

So again, investigate fully FIRST. Installing things first and investigating after the smoke escapes is expensive.
 

hondastang

Member
Location
Duluth, MN
Transfomers

Transfomers

Hello just to let you know. Between 3 mechanical engineers it end up the tranformer they needed was isloation transformer. 480 delta to 480 wye. I had too many telling me what they wanted. Thanks for the help
 

templdl

Senior Member
Location
Wisconsin
Maybe you meant 112.5 kVA, 480-208/120v transformer!
Still, why did "they" think there's a problem with having 480V supplying 460V equipment? (4% difference in voltage).

Right on! 480v is apwhat is consided a nominal voltage. The OP never stated what the application is which is not all that unusual but it could be that there is a motor or motors with a 460v nameplate voltage which is standard. Motors are rated this way because it is anticipated that they will be used with a 480v system but will actually be applied at a lower voltage due to a voltage drop, I.E. around 460v. In any event it is common for motors to operate satisfactory at +-10% try heir nameplate voltage anyway.
But this is only guessing at what the OP's application is and the ratings of the loads are.
 
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