Majority of Pune residents woke up to a power outage on Wednesday morning following a major fault on the 400-KV high-tension lines of Maharashtra State Electricity Transmission Company Limited (MSETCL) at Chakan and Lonikand. Where does Pune get its power supply from, and what exactly caused the power outage? The Indian Express explains.

Since the reorganisation of the erstwhile MSEB (Maharashtra State Electricity Board) in 2005, three entities coordinate the generation, transmission and distribution of power in the state — Maharashtra State Electricity Generation Company Ltd (MahaGenco), Maharashtra State Electricity Transmission Company Ltd (MSETCL) and Maharashtra State Electricity Distribution Company Ltd (MSEDCL).

Simply put, the power grid in the state mainly receives power from various power generation plants in the state. Power transmission substation of various high voltage capacities such as 765 Kilovolt (KV) and 400 KV form the main distribution points on these transmission lines in the state. It was the fault in high tension lines to two such 400-KV substations in Chakan and Lonikand in Pune district that led to the power outage on Wednesday morning.

Pune mainly receives its power from five such 400-KV power substations — Chakan, Lonikand 1 and 2, Jejuri and Talegaon PG (Power Grid). The 400-KV transmission lines which come to these substations are further distributed and emerge as 220-KV power lines and further into-132 KV transmission lines. MSETCL manages a network of over 640 sub-stations of this Extra High Voltage range spread across over 46,000 circuit km of transmission lines.

The 132-KV transmission lines get further divided into 33-KV transmission lines and substations, which are controlled by the MSEDCL. The 33-KV lines are further distributed into 22-KV and 11 -KV lines and further stepped down by transformers to 440/220 volt lines, from which consumers of various categories, such as domestic, commercial, agriculture and industrial, get their supply. Some of the very high-consumption customers, such as industrial units, can also get their supplies from high-tension lines above the chain.

Maharashtra has a network of more than 4000 33KV and 11 KV substations, 25,000 high-tension lines, 3.8 lakh km of 11-KV lines, 50,000 km of 33-KV lines. MSEDCL supplies power to 3.08 lakh square km of area, 457 towns and cities and 41,928 villages in the state.

The MSEDCL has 14 zones, 43 circles and 629 sub-divisions in the state. Pune zone is divided into three circles — Rasta Peth, Ganesh Khind and Pune Rural circle. The circles are further divided into divisions and sub-divisions. These administrative units look after the the respective sub-stations and transmission lines in their respective jurisdiction.

What exactly caused the outage?

Technical snags were reported in many as five circuits on the high-tension tower lines of MSETCL running between Lonikand to Chakan and Chakan to Talegaon due to heavy fog and resultant dew. This snag disrupted the Extra High Voltage (EHV) power supply to Chakan and Lonikand sub-stations. This resulted in stoppage of power supply to 189 sub-stations of the MSEDCL. This affected power supply to 15.13 lakh consumers in Pune, 7.25 lakh in Pimpri-Chinchwad and 1.8 lakh in Lonikand — a total of 24.18 lakh consumers in total.

Officials said that heavy fog affects the transmission lines by causing reduction of creepage distance — the distance between two conductive parts measured along the insulator. The factor, which is weather dependent, is key to the functioning of insulators on high-tension transmission lines.

How was power finally restored?

Responding to the situation, a contingency plan was put in place by senior officials of MSEDCL and MSETCL. Power generation from Koyana Hydroelectric project was stepped up and additional power was supplied to the 400-KV substation at Jejuri. Meanwhile, efforts were launched to repair the snags developed in the MSETCL transmission lines, which involved some extremely risky work from the technicians.

After availability of additional power of around 1000 megawatt from Koyana to Jejuri sub-station, MSEDCL started efforts to restore power to its consumers from around 8.30 am. By 12 noon, power to nearly 80 per cent of affected consumers had been restored. Power supply to areas which have hospitals, transport utilities and water supply systems was restored initially, followed by domestic consumers.

By around 1 pm, the snag of two of the five points were resolved and power supply was further restored.

All the five points with technical snags became functional by 3 pm. In Pune city, supply to areas like Rasta Peth, Bundgarden, Parvati, Kothrud, Nagar Road and Shivajinagar was restored by 11.30 am. By 12 noon, power supply resumed in most areas of Pimpri-Chinchwad while the remaining areas started receiving power supply by 3.30 pm. Chakan industrial area got back power supply by 12.45 pm.

Newsletter | Click to get the day’s best explainers in your inbox

🗞 Subscribe Now: Get Express Premium to access the best Election reporting and analysis 🗞️

For all the latest Explained News, download Indian Express App.

Sushant KulkarniSushant is Principal Correspondent with The Indian Express’ Pune bur... read more