Dear Gopu,
Transfer Policy is a part of HR Policy itself. There are various modalities & benefits (some times deduction also applicable) would accrue in transfer cases. Normally these benefits go by the status and difficulties associated with the place of postings. Very rarely additional increments are given when HR policy provides for it. Other wise allowances associated in such places are given where additional expenses are to be incurred such as remote areas, hilly/icy terrain etc. However in your case it's from Puduchery to Chennai transfer would involve hike in HRA, CCA commensurate with 'A' class (metro) cities. If you are a small private firm you might rarely follow emoluments broken into Basic, DA, HRA, CCA pattern instead a consolidated salary may be in vogue. In which case a lump sum increase or certain %age, (say @ 10% on basic etc.) for the period of posting in Chennai/TN could be considered. The quantum is left to you and it should be attractive as well, to lure them to accept the transfer readily though transfer cannot be refused by an employee as per service conditions (refer your apptt. order or HR Policy).