CCT from the same batch, why???

[choi1167]

Any technical info on why is it necessary for the cross-current transformer (CCT) to be used for paralleling multiple generator sets to be manufactured from the same batch?

 

[mpparent]

It's always good to have matching CT's so you don't have mismatch/error.

Mike

 

[choi1167]

So, are you saying that if all the CCT's came from the same batch, with the same ratings, ratios, etc. the system will guarantee a mismatch/error free?
What about if you're adding new generator units to existing ones with the same brands, ratings, etc., obviously the CCT's are not from the same batch. So, is it necessary to replace all the CCT's and order all coming from one same batch to satisfy the requirement and make it mismatch/error free?
On the other hand, what will be the worst scenario if these CCT's are not manufactured from the same batch?
Are there any existing literature or standards regarding this? Any input will be greatly appreciated. Thank you.

 

[AusLee]

A worst case scenario will be one CT reporting erroneously on the Ampd drawn from one source therefore forcing regulation which will cause the output to fluctuate because there was no need for the regulation. So you will get instability limited within the range of the controller. Mathematically it is sufficient that the new CT be of the same Class as the others.

 

[choi1167]

I agree. It should be sufficient that the CCT's are from the same manufacturer, same model, same class, same ratings, etc. though may not be from the same batch.