IEC 60305: Overhead Line Insulators — Radio Interference and Corona Testing

Where Does the “Hissing” on HV Lines Come From? Insulator Corona Discharge and Radio Interference

IEC 60305:1995 specifies overhead line insulator radio interference (RIV) and corona testing. Corona discharge on HV insulator surfaces generates HF electromagnetic radiation (0.5–30 MHz), potentially interfering with AM/shortwave radio and PLC. RIV is measured in dB(μV) at 1 MHz.

TNLab — HV line “hissing” is not harmless background noise — it is an early signal of insulator surface ageing.