In 1997 year
1) Bhel2) ONGC
3) IOC
4) HPCL
5) BPCL
6) GAIL
7) SAIL
8) NTPC
9) MTNL
(I dont know about the year they get the status)
10) HAL (Hindustan Aeronautics Limited)
11) NALCO (National Aluminium company limited)
12) NMDC (National Mineral Development corporation)
13) PFCL (Power finance corporation Limited)
14) BEL (Bharat electronics)
In 2008
15) Powergrid Corporation
16) Rural Electrificaion Corporation