Midnight outage hits TN power demand by 1,300-1,400 MW

CHENNAI: After the major power outage in and around Chennai on Thursday night, the Southern Regional Load Despatch Centre (SRLDC) has pegged the State’s power demand loss at 1,300-1,400 MW as per the SCADA (Supervisory Control and Data Acquisition System) data.

The city’s power demand ranges from 3600-3800 MW in September, which would dip when it starts raining. If one goes by the SRLDC estimate of the load loss, the city’s demand might have gone down by 34% or nearly one-third on Thursday night.

According to SRLDC’s Grid Event Flash report, the 400 kV NCTPS-Manali line tripped on the R-B fault at 8.11 pm on Thursday, leading to an increase in the flow of 400 kV Alamathy-Manali to 819 MW, which also tripped due to line isolator fire at Alamathy at 9.54 pm, the report said.

Following a massive blackout, electricity supply was restored in phases starting from midnight, with all areas receiving normal power supply by 2 am, said Tangedco on Friday. Power supply was disrupted in localities including Manali, Madhavaram, Kolathur, Tondiarpet, Purasawalkam, Perambur, Otteri, Egmore, T Nagar, and Adyar.

The outage was a result of a major line isolator fire at the Alamathi 400/230 kV substation (SS) on September 12 around 9:58 PM. “This incident led to the tripping of two 400 kV power sources — Alamathi and NCTPS II (North Chennai Thermal Power station) — and a jumper disconnect. The fire was quickly extinguished, but the dual power source failure caused power outages in some areas of Chennai,” said Electricity Minister Thangam Thennarasu in a social media post.

Tangedco confirmed that the blackout did not affect essential services such as at hospitals in the city and suburbs.

The Manali SS is a critical power source for the city, receiving power from the Alamathy and NCTPS II substations and providing 800-900 MW to substations in the city like Pulianthope, Tondiarpet, Mylapore, RA Puram, Basin Bridge, Vysarpadi, and Sembium. These supply power to important city areas including Anna Salai, Parrys, West George Town, Egmore, Chintadripet, Mylapore, Luz, Santhome, Nungambakkam, Royapuram, Tondiarpet, Tollgate, Saidapet, Vysarpadi, Sembium, Kolathur, Periyar Nagar, Madhavaram, Puzhal, Red Hills, and Kodungaiyur.

Tangedco engineers began the work to restore the supply through a back feed at 11 pm. They identified jumper cut in 230 kV North Chennai-Tondiarpet feeders 1 and 2, the kV Kalivendampatti-Taramani feeder, and also the 230 kV Sriperumbudur-Taramani feeder. Despite the setbacks, Tangedco stated that supply was restored to Anna Salai, Chintadripet, Nungambakkam, Sembium, and Periyar Nagar at midnight. By 1 am, supply was restored to Pulianthope and Kolathur, with Mylapore, Vysarpadi, Adyar, and Ennore areas following suit at 2 am.