Q: If purity drops to 95% due to air ingress, will the GIS still work?
A: It will stay energized, but safety margins (arc quenching and cooling) are dangerously reduced.
Risks of Low Purity:
❶ Reduced Arc Quenching: Air is 100x worse than SF6 at stopping arcs. CB might fail to interrupt.
❷ Heat Dissipation: Contamination changes gas density and cooling ability, leading to overheating.
Standards (IEC 60480):
• New Gas: ≥ 99.9%.
• Running Gas: Must be > 97%. Below 95% requires reclamation.
How do we interpret SO2 and HF levels?
Q: Analyzer shows 5 ppm of SO2. Normal result or internal fault?
A: SO2 is the "Smoke Alarm" for internal arcing. Interpret as follows:
|
SO2 Level |
Interpretation |
Action |
|
< 1 ppm |
Normal operation. |
Routine monitoring. |
|
1 – 5 ppm |
Minor PD or heavy switching. |
Shorten test interval. |
|
5 – 10 ppm |
A significant defect occurred. |
Investigate using UHF/Acoustic PD. |
|
> 10 ppm |
CRITICAL internal damage. |
Immediate inspection/purification. |
Expert Tip: If both SO2 and HF are high, you have an ACTIVE defect generating acid right now.