Repetitive Voltage Transformer Failure – Root Cause Analysis
Reliable operation of voltage transformers is critical for the stability of industrial substations. In this case, a plant faced repeated voltage transformer failures at the 33 kV bus despite replacements and countermeasures.
High-voltage transients caused by sudden load shedding were found to stress the VT insulation, leading to short circuits and fuse failures.
Problem Statement
1. The plant experienced chronic voltage transformer failures on the 33 KV bus, even after multiple replacements.
2. These failures were linked to switching transients and insulation breakdown in the VT’s primary winding.
3. Frequent VT damage led to protection loss, system blackouts, and increased O&M costs.
4. A root cause analysis was needed to design a reliable mitigation solution, such as a snubber circuit.