blocked credit

Yes ITC available and there is no restriction under section 17(5) I.e. Blocked credit restricting the eligibility to claim ITC on electrical transformers.
Further, such electrical transformers are being used or intended to be used in the course or furtherance of business, it qualifies the conditions for availing ITC as per Sec. 16(1) and that too the person availing ITC can treat it as capital goods as these are being capitalised in the books of such person.