IEC 60034-27-3 is the standard that governs dielectric dissipation factor — tan δ — measurement on the stator winding insulation of rotating machines. This is a section-by-section walk through the document, in the order the standard itself uses, so you can find and understand any clause quickly. For the test in practice rather than the document structure, start… Read More: IEC 60034-27-3 Explained: Clause-by-Clause Guide »
A withstand test tells you the insulation did not break down for one minute. It tells you nothing about what happens over ten years. Solid insulation with a void inside will pass a hipot shot and still erode from the inside out, one small discharge at a time, until it doesn’t. That’s the gap a partial discharge test… Read More: Partial Discharge Test for Solid Insulation in Low-Voltage Equipment »
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 »
Every power transformer above 72.5 kV gets an IVPD test before it ships. The test takes more than an hour, costs the manufacturer significant test bay time, and is the final dielectric test in the sequence. Why? Because partial discharge is what kills transformer insulation slowly, and most other tests can’t see it. A lightning impulse test stresses… Read More: The IVPD Test Explained: Why Power Transformers Are Tested for… »
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… »
You’ve decided your equipment needs partial discharge testing. The next question is operational: do you take the equipment out of service for offline measurement, or install sensors and monitor while it operates? The answer drives equipment selection, budget, outage planning, and the diagnostic value you’ll get. This article compares offline and online PD testing in detail — how… Read More: Online vs Offline Partial Discharge Testing: Which Method, When, and… »
A motor passes its insulation resistance test with a 500 MΩ reading and a PI of 3.2. Six weeks later it fails catastrophically in service. How? The IR test was measuring the bulk resistance of the insulation system, but somewhere inside the winding there was a tiny void in the epoxy-mica tape. That void had been producing partial… Read More: Partial Discharge Testing vs Insulation Resistance: When Each Matters »