2 power transformers

[Mosquito]

To whom it may concern,

I would like to put in paralell 2 power transformers of each 1000KVA, 50Hz, 15KV(primary/400Volts(secondary).
1) actually what do I need to both transformers in paralell(low voltage side)? a syncroniser?only 2 circuit breaker for each transformer and a main one to suply the load?
Please help.
Thanks, Mosquito.

 

[augie47]

are both transformers fed from the same primary source ?

 

[Mosquito]

Yes they are fed from the same source(15KV, 50 Hz). Actually they are sitting in the same control room. Mosquito.

 

[Besoeker]

To whom it may concern,

I would like to put in paralell 2 power transformers of each 1000KVA, 50Hz, 15KV(primary/400Volts(secondary).
1) actually what do I need to both transformers in paralell(low voltage side)? a syncroniser?only 2 circuit breaker for each transformer and a main one to suply the load?
Please help.
Thanks, Mosquito.

Since they come from the same 15kV supply the frequencies will be the same so frequency synchronisation isn't an issue.
But you need to be sure that the transformers have the same vector configuration and the same impedance.

 

[Mosquito]

Since they come from the same 15kV supply the frequencies will be the same so frequency synchronisation isn't an issue.
But you need to be sure that the transformers have the same vector configuration and the same impedance.

The impedance is on the plate. How do I know if they have the same vector configuration(is this phase rotation?)? Is the impedance an issue because they are in parallel? Mosquito

 

[Besoeker]

The impedance is on the plate. How do I know if they have the same vector configuration(is this phase rotation?)? Is the impedance an issue because they are in parallel? Mosquito

The vector configuration is also usually given on the nameplate.
If they are not the same, parallel connection is not possible.

 

[bob]

Should be on the nameplate. Look here http://www.transformerworld.co.uk/vector.htm

 

[zog]

Also keep in mind when you parallel those 2 transfomers you will about double your available fault current and will likely exceed the AIC ratings of your switchgear. I sure hope you have looked at that already.

I haev seen the aftermath of this mistake and it is ugly. Not for me, I provided an entire double ended substation and 2 transformers that weekend, but ugly for the owner and the engineeer that had made that decision.

 

[Mosquito]

Also keep in mind when you parallel those 2 transfomers you will about double your available fault current and will likely exceed the AIC ratings of your switchgear. I sure hope you have looked at that already.

I haev seen the aftermath of this mistake and it is ugly. Not for me, I provided an entire double ended substation and 2 transformers that weekend, but ugly for the owner and the engineeer that had made that decision.

Thanks, I will look into that! What about the low voltage side, I think I need to check phase rotation between the 2 transformers, I mean phase A of transformer 1 has to hook up with phase A of transformer2 and so on...Correct?

 

[Mosquito]

Thanks, I will look into that! What about the low voltage side, I think I need to check phase rotation between the 2 transformers, I mean phase A of transformer 1 has to hook up with phase A of transformer2 and so on...Correct?

Thanks, I will look into that! What about the low voltage side, I think I need to check phase rotation between the 2 transformers, I mean phase A of transformer 1 has to hook up with phase A of transformer2 and so on...Correct?[/QUOTE]

 

[zog]

Thanks, I will look into that! What about the low voltage side, I think I need to check phase rotation between the 2 transformers, I mean phase A of transformer 1 has to hook up with phase A of transformer2 and so on...Correct?

I am talking about the LV side and you need to check what your fault currents will be before you proceed futher. I had assumed you had but was just checking.

You will need the same %Z on both transformers, same phase sequence and ratation and check to make sure you do nto have a phase shift.

How do you physically plan on paralleling them? Tie breaker?
Why do you feel the need to do this?