Transformer Connection Change

If you are using it as a step up or step down transformer, I dont see a problem with using a star connection instead of a delta connection, just dont try and overload the transformer ratting.

My son, you have my blessing, go forth and connect in star. But I have not been able to view the web site, it's not operating, but I dont think you will have any problems, obvisouly it is a six terminal 480 output, this means you can do what you like.

Try and enjoy

Friends,

Because each of the windings has both ends brought out without internal connections, yes, you can connect the transformer's primary side in either star or delta. However, this does not change the turns ratio for the windings. In star connection, each of the windings would be putting out 480V, with phase-to-phase voltage of 831V (using tap 3). Therefore you would have a primary side of 831/480V, which has no normal or rational use in the electrical trade.

In theory, you can connect it in star; in practice your results will not be the 480/277V you expected.

--John M.

John M.

Thanks for your explanation. it makes a lot of sense and confirms what we thought we'll happen. I did not think it would hurt the transformer but it would not give us the desired voltage.

So basically what you are saying is:

In a Delta system (Which is the existing configuration of the transformer)

line voltage= Phase voltage (in this case 480 VAC)

Were i to change to a star connection the phase voltage would still be 480 VAC.

Moreover normal Y system:

line voltage= phase voltage (1.732)

Hence the line voltage= 831 VAC (as you pointed out in your comment)

Makes a lot of sense.

Thanks again for your response John!

Guest,

Guest #2 has valuable thoughts also. Some of the transformers have the transformer windings brought out to small pieces of bus bar mounted side-by-side on an insulator rail. The taps are small loops of the square formed-coil windings--you connect to the desired one by scraping the varnish off the sides of the loop and bolting the flexible-stranded tap cable onto the desired loop. This type of construction may only have three pieces of bus bar for the high-voltage connections (because they were to be delta). So, connecting it star could entail a splice that is not on the insulator rail alongside the other normal connecting points.

--JMM

You can connect HV side in star , but note followings:

1. Check and confirm whether the insulation / clearance between adjacent HV line leads and between windings are adequate for continuous voltage rating of 831 V or so.
2. Voltage ratio will increase by sqrt (3) times.
3. Current rating of HV side will reduce by sqrt (3) times.