Summary
The 400/220 kV Mandola substation of the transmission system operator(TSO), commissioned in the early 1990s, was designed for short-circuit levels prevailing at that time. Progressive transmission network strengthening and large-scale generation integration have since resulted in short-circuit levels exceeding original equipment fault-duty ratings. The substation is also subjected to a high incidence of faults—approximately 80–100 events annually— predominantly originating from the 220 kV network and downstream systems. These frequent through-faults impose severe thermal and electrodynamic stresses on switchyard equipment, particularly interconnecting transformers, leading to progressive insulation degradation as evidenced by Dissolved Gas Analysis.
Read more Read lessThis paper presents operational experience from Mandola substation and evaluates the cumulative impact of recurrent through-faults on equipment performance, reliability, and residual life. Mitigation measures adopted include adaptive auto-reclosure schemes, selective equipment uprating, mechanical reinforcement of bus conductors, installation of currentlimiting series reactors, and strengthened condition-based monitoring. The paper demonstrates how a coordinated combination of system, equipment, and monitoring interventions can sustain reliable operation of legacy Extra High Voltage(EHV) substations under increasingly stiff, high fault-level network conditions.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | B3_10467_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | India |
| Study committees | |
| File size | 1 MB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
BHAKAL* Ramjash - POWERGRID , INDIA; JHA Pankaj Kumar - POWERGRID , INDIA; SAHU Kuleshwar - POWERGRID , INDIA
