Govt directs utilities like Adani & NTPC to maintain EHV transmission towers after 75 failures. Climate change & wind are factors.
As per the minutes of the meeting of the committee, a change in the wind intensity in certain parts of the country on account of climate change has been observed as one of the key reasons for the failure of the EHV transmission line towers, which play a crucial role in the transportation of large amounts of power over long distances.
A total of 75 EHV transmission line towers in 22 transmission lines failed between January and June 2025 or H1, owing to a number of reasons that need to be checked and timely reported by the utilities.
These assets are owned by 12 players, including Adani Transmission, ReNew Transmission Ventures, Resonia Limited (erstwhile Sterlite Power Transmission Ltd), Powergrid and NTPC, said the report by the Standing Committee of Experts constituted by the Central Electricity Authority (CEA).
As per the report, the main cause of tower failures is attributed to high-intensity wind as reported by the transmission utilities. The wind intensity has changed in certain parts of the country due to climate change. However, the utilities failed to produce wind data in many cases of EHV transmission line tower failures, which could substantiate their reasoning.
Other reasons for failure of EHV line towers include damage to the foundation, tower structure and deformation in the legs of towers and the cage portion of the bottom cross arm level.
To avoid such incidents, the CEA has advised the utilities to refer to the wind map provided in the National Building Code for the design of towers till the revised wind map has been included in IS 875. SERC, in coordination with IMD, has been requested to update the wind map.
It said transmission utilities need to take proactive measures like increased line patrolling and immediate replacement of missing members/bolts. Various deficiencies, such as missing members, missing bolts, bent members, incorrect attachment of cross arm, chimney covered with soil, and rusted stubs/members, have been observed during the failure site visit of various transmission towers of different utilities.
Utilities should take necessary precautions and carry out proper maintenance of their lines to avoid failure of towers due to such deficiencies, it added.
The transmission towers erected near river banks should be frequently patrolled, and an assessment based on history should be made to anticipate the change in the course of the river, and necessary protection should be provided to towers to avoid their damage during such an incident.
For towers located in overlapping wind zones, the Committee recommended that the higher wind zone shall be considered if the tower is situated within 50 km of the border area, and the tower may be designed accordingly.
It has also recommended that the utilities develop in-house teams equipped with relevant tower design software to simulate, analyse, and address design issues in failed towers.
The CEA committee has also advised that the digitisation of spares and inventory management of transmission system assets using suitable software like SAP shall be taken up on a priority basis.
Utilities are also asked to submit the actual wind velocity prevailing in the affected area so that the investigating team of the Standing Committee can get the reference wind speed that prevailed over that area. In this matter, the respective utility may seek the help of IMD/ nearest Airport/ nearest wind farms, or the State Irrigation Department to estimate the wind speed in the affected area based on data obtained from observatory/ Satellite/Radar.
Utilities should furnish a closure report for the event within 3 months, including all the details and records. All utilities are requested to adhere to these timelines strictly, it noted.