Ntpc Limited · Ptc India Limited · National Power Exchange Limited · Ongc Tripura Power Company Limited · Ntpc Bhel Power Projects Private Limited · Aravali Power Company Private Limited · Ntpc Vidyut Vyapar Nigam Limited · Energy Efficiency Services Limited · Ntpc Sail Power Company Limited · Meja Urja Nigam Private Limited · U40101 Tr2004 Ptc007544