In our organization we had two 4000 KVA transformer in parallel operation.Now we want to purchase an additional 4000 KVA transformer in case of failure of the existing transformer.
These transformers were installaed 30 years back all the data[NAME PLATE AS WELL AS TESTING & COMMISSIONING ] is not available with us , mainly percentage impedance and No Load Loss & Full load loss which are essential for parallel operation.
So I want to know wheather is it possible to purchase a transformer for successful parallel without these data ?
Is there any other way to find out the data require for parallel operation ?