If two 100 KVA transformers are connected in parallel, in the primary windings (3-phase, 440V, 50 Hz) through a common isolator, will there be any detrimental effect on the transformers during switching off of the isolator due to the surge voltages generated? If yes, one option is to connect the primary windings through two different isolators. Is there any other possible connection to avoid it?
Regards,

Pradeep Chatterjee
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Why do you want to connect two 100 Kva transformers in parallel with one isolator?
It is basically two inductors in parallel and the effective inductive voltage produced on switch off will not be to the effect of damaging the transformers.
The highest inductive voltage on switch off is produced when you there is no load on the transformers (the inductance is greatest).
Sekar

 

Responding to P. Chatterjee's Aug 28, query:

Connecting two transformers to the same primary isolator will not produce any detrimental effects during "switch off". This arrangement is common industrial practice for much larger transformers having higher primary voltages!

However, there is a cautionary comment regarding the ability of the isolator to withstand the magnetizing inrush current when the isolator
is "switched on".

If you want more info, please provide additional details.

Regards,
Phil Corso, PE
(Boca Raton, FL)