Failure of 28 transmission lines of voltage 220kV or above were reported during the period January 1, 2024 to December 31, 2024 to the Central Electricity Authority, as per a newly-released standing committee report.
The report of the Standing Committee of Experts on Failure of EHV Transmission Line Towers (January 2024 to December 2024) was recently released by Central Electricity Authority (CEA).
The objective of the Standing Committee is to investigate the causes of failures, deliberate the failures of transmission line towers of various power utilities, suggest remedial measures to prevent recurrence of such events in future and prepare a report which would serve as a repository of case studies of failures and suggested remedial measures for future.
The key findings and recommendations contained in the are summarized below:
- Failure of 28 EHV transmission lines were reported during 2024, caused by 76 tower failure incidents. Of these 68 were suspension-type towers and the remaining 8 were tension-type towers.
- The aforementioned failures were reported by 12 utilities – PGCIL, AESL, RVPN, MSPCL, APTRANSCO, MSETCL, HVPNL, GETCO, MPPTCL, DTL, DVC and NTPC. (Key to abbreviations provided at the end of the story.)
- Of the 28 line failure cases, majority (14) were of the 220kV type, 11 of 400kV and three of 765kV type.
- The much higher failure rate of suspension-type towers was explained by the fact that in normal terrain, the number of suspension-type towers used in a typical transmission line is much higher than that of tension-type towers. Also, suspension type towers are not designed to take horizontal forces in the longitudinal direction and hence the failure of one suspension tower causes secondary failure of adjacent suspension towers due to pulling force of conductors.
- Across all the voltage levels (220kV, 400kV and 765kV), reasons for tower failure included: deformation in legs of towers and cage portion of bottom cross-arm level; buckling at stub level leading to complete collapse with/without damage to tower foundation; damage to tower foundation and tower structure due to increased water level, soil erosion and inadequate protection to tower foundation, etc.
- The main cause of tower failures was attributed to high intensity of wind as reported by the 12 utilities. However, many utilities failed to produce wind velocity data in many cases so as to substantiate their reasoning.
- The standing committee observed that when tower failures due to wind are reported by utilities, they must furnish wind velocity data from observatories of Indian Meteorological Department (IMD) or the nearest airport.
- The committee also highlighted that due to overall climatic changes, incidents of high winds are increasing. Transmission utilities therefore need to take proactive measures such as increased line patrolling and immediate replacement of missing members or bolts.
SC Background
A standing committee (SC) of experts was constituted by CEA in September 1999 and reconstituted in August 2012, with the objective of investigating the failure of transmission lines of 220kV or above, and for recommending remedial measures to avert failures in future. In this connection, a meeting of the SC was held in April 2025 to study transmission line failures in the period January 1, 2024 to December 31, 2024. The SC has been meeting regularly since 2014. Incidentally, the highest number of transmission tower failures, at 163, were reported in 2014.
Key to abbreviations
PGCIL: Power Grid Corporation of India Ltd; AESL: Adani Energy Solutions Ltd; RVPN: Rajasthan Vidyut Prasaran Nigam Ltd; MSPCL: Manipur State Power Company Ltd; APTRANSCO: Transmission Corporation of Andhra Pradesh Ltd; MSETCL: Maharashtra State Electricity Transmission Company Ltd; HVPNL: Haryana Vidyut Prasaran Nigam Ltd; GETCO: Gujarat Electricity Transmission Corporation Ltd; MPPTCL: Madhya Pradesh Power Transmission Company Ltd; DTL: Delhi Transco Ltd; DVC: Damodar Valley Corporation; NTPC: NTPC Ltd.
Note: The full report is available on CEA’s official website, and may be accessed using this external link.
Featured photograph (source: CEA) is for representation only