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 »
You have two different windows into a transformer’s health. One is the DGA report — a lab analysis of gases dissolved in the insulating oil. The other is a PD test — a direct measurement of partial discharge activity in the windings. Both diagnose insulation problems. Neither alone tells the full story. When they agree, you have high… Read More »
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 »
A single insulation reading tells you the condition today. A thousand readings over a decade tell you when the equipment is going to fail. That’s the difference between preventive maintenance and predictive maintenance. Preventive says “test every 6 months.” Predictive says “this motor’s PI has dropped from 3.2 to 2.4 over the last four tests. At this rate… Read More »