three phase transformer

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shaw0486

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Hi,
I have a project that the engineer wants a three phase 4 wire system at 230 volts. There is no such transformer so he has requested that we accomplish a three phase 4 wire system with three single phase buck boost transforemers and this does not seem at all correct to me but I cannot identify the issue with it. What do you guys think?
 
shaw0486 said:
Hi,
I have a project that the engineer wants a three phase 4 wire system at 230 volts. There is no such transformer so he has requested that we accomplish a three phase 4 wire system with three single phase buck boost transforemers and this does not seem at all correct to me but I cannot identify the issue with it. What do you guys think?
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Transformer manufacturers can make any configuration you heart could possibly desire.
 
shaw0486 said:
Hi,
I have a project that the engineer wants a three phase 4 wire system at 230 volts. There is no such transformer so he has requested that we accomplish a three phase 4 wire system with three single phase buck boost transforemers and this does not seem at all correct to me but I cannot identify the issue with it. What do you guys think?
Click to expand...
Three phase 4 wire 230 (240 nominal) does exist and is relatively common, just not common everywhere. The system that is common is a delta connected secondary that 120/240 volts with one phase being a high leg with 208 volts to neutral.

If you build a wye system that is 240 volts phase to phase the voltatge to neutral will be about 138.5 volts a little too high for supplying 120 volt loads so when you do see such a system it is typically only intended to supply 240 volt loads only.
 
He may me going by what some of the UL listings on motors, lights etc.. As a lot of manufactures test equipment on 230 volts. Knowing very well they will be used on 240.
 
Look at 'drive isolation transformers', these are commonly supplied with nominal 230Y/133V secondaries.
 
shaw0486 said:
It is not a stock item. Project is three weeks. If you can answer my question that would be helpful!!
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More details of what your needs are may help with coming up with an answer.

Do you need 230 volts as mentioned or is a 240 volt nominal system acceptable.

High leg delta secondary is not as common and may be special order so I can understand a delay, but is not really a customized item either.

Is it acceptable to use a 208 volt system? 120 volt loads will not care which system they are connected to and may be the way to go if you have a lot of 120 volt load and use buck boost for a specific 230 volt load(s).

If a lot of the capacity is needed at 230 (240) volts for some reason and you can't get your transformer in time you can network three 120/240 single phase transformers together to build a three phase system, or even build an open delta if there is limited three phase load which would save some $$$ over a full delta.

Just some suggestions to throw out there not knowing what your needs really are.
 
Can you confirm to us that you have a three phase system with 120 volts line to neutral and 208 volts line to line (commonly written 208Y/120)?
Does your engineer want 230V line to line?
As stated earlier a NEMA standard motor whose nameplate reads "230" is really intended to work with a nominal supply voltage of 240V.
In any case you can create the voltage you need with three boost transformers. Just connect each transformer with its 120V primary from line to neutral. A 10V secondary winding will give you almost exactly 240V line to line. A 6V secondary will give you close to 230V line to line if that is what you really need. Even though your boost transformers are wired in wye, you will have no issues running a load that is wired in delta.
Note also that some motors that list 230V on the nameplate can be run at 208V at a reduced power and torque.
 
GoldDigger said:
Note also that some motors that list 230V on the nameplate can be run at 208V at a reduced power and torque.
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And some have right on the nameplate a higher current value if operated on a 208 volt system, should still give same output power and torque just at a higher input current level.
 
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