Why transformers are operated in parallel

Explain the reason for operating the transformer in parallel

Because of load increasing and cost optimization. Suppose the existing installed Transformer is 1 MVA that installed since 10 years ago, during the 10 years the load demand is increased and the existing 1 MVA is in overload condition as ( the increased load within 10 years suppose to be 200 kVA ) then the solution to satisfy the increased load and bigger transformer size requirement, we have to purchase new 2 MVA transformer ( but the future load increasing till next 10 years will not reach 2 MVA and the existing 1 MVA will be extra ) then the solution as purchase new another 1 MVA Transformer with same technical particulars with existing TX and that two TX will be operating in parallel operation as 1 MVA + 1 MVA = 2 MVA on the same bus ( not the two separate supply as 1 MVA - 2 Supply Source ). The same kVA Rating can manage/control the equal load sharing between the Two TX ( the best parallel operation on the same rating ) but the different kVA ( 1 MVA + 500 kVA but within in same limited % impedance ) is also possible for parallel operation but need to make proper load sharing between the two parallel transformers as this will cause continuous overload on less kVA ( Rating TX )