However, anti-nuclear power activists questioned when the unit would start commercial operations as it is more than six months since the unit was synchronised with the grid.
According to POSCO, the KNPP unit reached peak power generation of 876 MW and the average generation for the day was 810 MW.
India's atomic power plant operator Nuclear Power Corporation of India Ltd. (NPCIL) is putting up two Russian nuclear power plants at Kudankulam in Tirunelveli district, around 650 km from here.
The NPCIL got the nod from the Atomic Energy Regulatory Board (AERB) early this month to increase the KNPP first unit's power levels above 75 percent.
The first unit was connected to the southern grid last October.
Speaking to IANS, G.Sundarrajan, an anti-nulcear power activist who has filed a case against KNPP in the Supreme Court, said: "The first unit was connected to the grid last October and it is more than six months but NPCIL has been postponing the commercial operation of the unit without giving proper reasons."
According to NPCIL, the first KNPP unit is expected to begin its commercial operations this month.