According to POSOCO, two other units of NCTPS (one 600 MW and another 210 MW) went out of operation on Monday.
The expected date of resumption of generation by the three units is not known, said POSOCO.
Similarly, the two 220 MW units at Madras Atomic Power Station (MAPS), too, stopped operating on Monday evening due to tripping of power evacuation lines, POSOCO said.
According to POSOCO, the NCTPS Unit 1 was hand tripped due to heavy winds on Monday morning while the second 600 MW unit stopped due to electrical problem.
The reason for stoppage of 210 MW unit at NCTPS is awaited, said POSOCO.
Meanwhile, restoration of power supply in Chennai, Kanchipuram and Thiruvallur districts is likely to take a day or two as per the field staff of the state power utility.
However, top officials were not available to comment on restoration of power supply in the three districts affected by the cyclone.
In a statement issued on Monday late night, Chief Minister O. Panneerselvam said: "The Tamil Nadu Electricity Board has deployed 4,000 personnel to set right power lines damaged due to high speed winds that blew at a speed of 130 kmph when cyclone Vardah crossed coast near Chennai Port."
While all efforts would be taken to restore power supply at the earliest, it would take a couple of days for that to happen in some places in North Chennai, Thiruvallur and Kanchipuram districts, Panneerselvam added.