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IEC 60270: Partial Discharge Measurement — The Gold Standard for HV Insulation Diagnostics
What Does 10 pC of Partial Discharge Mean? Decoding Insulation Health on the pC Scale
IEC 60270:2015 is the definitive standard for partial discharge (PD) measurement. PD measurement can detect localized defects months to years before insulation breakdown — unlike other diagnostic methods, PD directly measures discharge activity inside insulation.
| Apparent Charge(pC) | Insulation Condition | Recommended Action |
|---|---|---|
| <10 pC | Normal — new equipment standard | Routine monitoring (typically annual) |
| 10–50 pC | Attention — localized defect | Shorten interval, trend tracking (3–6 months) |
| 50–500 pC | Warning — defect developing | Further diagnostics (DGA, tanδ), plan outage |
| >500 pC | Critical — near breakdown threshold | Schedule immediate outage and repair |
Apparent charge: q = C₀ × ΔV
Calibration pulse: ΔV=10V, C₀=5pF → q=50pC
Detector output: Vout = q × transfer impedance Z
Z depends on detector type (R, RC, RLC) and frequencyTN Lab — Partial discharge is the “early warning system” for HV insulation degradation. The pC is its universal language.
