The Challenge
A facility's 250 kVA generator developed bearing wear over 2 weeks. Sound changed noticeably in week 2 (knocking noise) but was attributed to 'normal operation variation.' Generator failed catastrophically (bearing seizure) when next started.
What Became Visible
Post-failure analysis showed bearing wear had accumulated gradually. Sound analysis revealed that baseline noise was 78 dB(A) at 75% load; noise increased to 81 dB(A) at week 1 (3 dB increase, barely noticeable to ear) and 84 dB(A) by week 2 (6 dB increase, double the energy). The trend was clear in acoustic data but invisible in manual observation.
What Changed
Continuous acoustic monitoring installed. Baseline sound level recorded during commissioning. Alert threshold set at +3 dB variation from baseline. Any sustained increase triggers inspection.
How it worked: An acoustic sensor recorded noise levels continuously at fixed generator operational point. Algorithms detected when noise exceeded baseline by 3+ dB, indicating early-stage mechanical issues. Bearing wear is detected at early stage when repair is still possible.
Results
before catastrophic failure
through early intervention
planned vs catastrophic failure
from emergency repair downtime
Acoustic monitoring is one of the earliest indicators of mechanical problems. Small sound changes (3–6 dB) signal developing issues long before failure.
Operational Reality
Most mechanical generator failures are preceded by audible changes 1–3 weeks before failure. Acoustic monitoring catches these changes automatically.