Short answer: A partial discharge (PD) test raises the voltage on a cable, holds it briefly, lowers it, and measures the tiny internal sparks that a defect gives off. Those sparks are reported as apparent charge in picocoulombs (pC). The cable passes if discharge stays below the declared sensitivity — 10 pC for cable, 5 pC for accessories… Read More: Partial Discharge Testing of Cables: How the PD Test Works »
Short answer: The routine AC withstand test applies 3.5 times the cable’s rated voltage (U₀) on medium-voltage cable, 2.5 times on high-voltage cable, and as little as 2 times on extra-high-voltage cable. The multiplier falls as the cable’s voltage class rises because the absolute test voltage would otherwise become impossible to generate and would damage the very insulation… Read More: AC Withstand Testing of Cables: Why the Multiplier Drops »
A 132 kV underground cable runs eight kilometers between two substations. After installation, before energization, a single test must verify that the cable, terminations, and joints will hold off operating voltage reliably for the next 30+ years. Insulation resistance testing won’t detect the small voids in joint accessories. Hi-pot testing might catch gross defects but won’t see the… Read More: Cable Partial Discharge Testing per IEC 60840: Field Procedures and… »
Cable insulation fails silently. Unlike a motor that vibrates or a transformer that overheats, a cable with degrading insulation gives you no warning until it faults. And when it does fault, it takes out the circuit — sometimes causing arc flash, fire, or hours of downtime while you trace the problem. Regular insulation testing on cables catches degradation… Read More: Cable Insulation Testing: How to Test, What Values to Expect,… »