Please I am fixing a small machine but the voltage to machine from
the US is not standard over here. The 3 phase we have here is 415
volts but this machine is rated 220 volt 3 phase (it has a 3 phase
motor). The problem is how do I get the 220 v 3 phase? In fact I used
3 separate auto transformers (not too similar) I observed the polarity
and connected it in Delta - Star but any time I put in power it
blows. I want to know whether the auto transformer is not suitable or
I should use an isolated primary and secondary winding transformer.
Apart from using a single 3 phase transformer is there any other
Method? Thanks

wrote:

Please I am fixing a small machine but the voltage to machine from
the US is not standard over here. The 3 phase we have here is 415
volts but this machine is rated 220 volt 3 phase (it has a 3 phase
motor). The problem is how do I get the 220 v 3 phase? In fact I used
3 separate auto transformers (not too similar) I observed the polarity
and connected it in Delta - Star but any time I put in power it
blows. I want to know whether the auto transformer is not suitable or
I should use an isolated primary and secondary winding transformer.
Apart from using a single 3 phase transformer is there any other
Method? Thanks
Use the WYE (star) config..

tie all of the low side of each auto exformer together.
feeders from your 415 connect to the high side of each autoxf.

the wiper will be your 3 phase output (adjustable).


http://webpages.charter.net/jamie_5"