Q: If we are doing a withstand test, why also monitor partial discharge?
A: Hipot is a "Pass/Fail" test; PD is a "Diagnostic" test. PD finds the root cause before the explosion.
Strategic Benefits:
❶ Safety Buffer: PD rising at 80% voltage allows you to STOP before the GIS is destroyed.
❷ Zoning: PD tells you exactly which gas compartment "tripped" during a flashover.
❸ Reliability: Finds defects that survive 1 min at test voltage but will fail in service.
PRPD Patterns - Identifying the "Tumor"
Q: How do I know if it is dust or a failing insulator from the dot cloud?
A: We use Phase Resolved PD (PRPD) patterns to fingerprint the defect.
|
Pattern Shape |
Diagnosis |
Threat Level |
|
Random Spots |
Moving Metallic Particles |
❌ Critical (Jumping danger) |
|
Symmetrical Clouds |
Internal Voids (Bubbles) |
⚠️ Warning (Electrical treeing) |
|
Stable Brush |
Fixed Protrusion (Burrs) |
❌ Critical (Stress concentration) |