conferred upon it under section 25 of the Customs Act, 1962 issued a notification no.208/88-Cus exempting machinery and equipment for generation of electrical power (including generating sets) of capacity of 2.5 MW or above but not exceeding 50 MW, from payment of customs duty in excess of 35% advalorem for a period upto 31st March 1989. By notification no.159/88-Cus dated 13th May 1988 also issued under section 25 of the Customs Act, 1962, the Government of India exempted several goods, which were granted full or partial exemption from customs duty, from payment of auxiliary duty of customs. On 10th September 1988, the petitioner placed orders for supply of two diesel generating sets of 4.3 MW each on Wartsila Diesel AB, Sweden for value of approximately Rs.3,86,73,175/-. After obtaining necessary licence from DGFT on 17th August 1988, the petitioner opened a letter of credit on 2nd January 1989 in favour of the vendor. The vendor shipped the diesel generating sets in several boxes. The first consignment valued at Rs.3,02,03,745/- appropriately arrived in the Port of Calcutta on 16th February 1989 and was cleared by the customs authorities applying the concessional rate of customs duty on the basis of exemption notifications referred to above. The balance cargo valued