transformer question

[difowler44]

We have a 480v 15kva 3 phase acme transformer (T3-53341-1S) we want to connect to a 240v single phase well pump 3hp. I know I make it single phase, but what is the amperage limit. Also need to know how to wire te 480v side. Is it same as Wye? It also shows delta on the diagram, but I know it can be wired to work.

 

[difowler44]

attachment for question

 

[LarryFine]

This is not the transformer you should be using. You need a 1ph 480-to-120/240v unit.

Note the Note in your pic.

 

[jim dungar]

We have a 480v 15kva 3 phase acme transformer (T3-53341-1S) we want to connect to a 240v single phase well pump 3hp. I know I make it single phase, but what is the amperage limit. Also need to know how to wire te 480v side. Is it same as Wye? It also shows delta on the diagram, but I know it can be wired to work.

Your single 3-phase 15kVA transformer is equivalent to three 1-phase 5kVA units, effectively you are only using 1/3 of its capacity. From a grounding and future troubleshooting aspect it would be advisable to use X1, X2, and X4, while paying attention to the note mentioned by Larry.

 

[difowler44]

This is not the transformer you should be using. You need a 1ph 480-to-120/240v unit.

Note the Note in your pic.

We already had this transformer. it is a temporary installation. So we didn't want to buy another transformer if we can make this one work. I saw the note. If it will produce 5kva, it will run the well pump

 

[difowler44]

Your single 3-phase 15kVA transformer is equivalent to three 1-phase 5kVA units, effectively you are only using 1/3 of its capacity. From a grounding and future troubleshooting aspect it would be advisable to use X1, X2, and X4, while paying attention to the note mentioned by Larry.

Thanks for the help. I was worried that the 5% note would exceed the limit of the transformer for a 3HP pump since 5% would be only .75 KVA according to the note. Is the 5% to prevent an imbalanced load on the three phase or specific to the transformer? I had hoped it would work but was concerned about the note as well. Sorry I am so ignorant on three phase transformers. We do 99% residential single phase.

 

[synchro]

Thanks for the help. I was worried that the 5% note would exceed the limit of the transformer for a 3HP pump since 5% would be only .75 KVA according to the note. Is the 5% to prevent an imbalanced load on the three phase or specific to the transformer?

The 5% limit is the maximum unbalanced 120V load relative to the 3-phase transformer's kVA rating.
And so it does not apply to 240V L-L loads.