Every insulation system leaks a little. Apply AC voltage across ground-wall insulation and the current splits into two parts: a large capacitive current that leads the voltage by 90°, and a small resistive current in phase with it that turns into heat. The dissipation factor — tan δ — is the ratio of those two. It is the… Read More: Dissipation Factor (tan δ) Test for Stator Windings »
Insulation testing in a wind turbine is not the same job as insulation testing in a plant motor room. The machine sits 80 to 150 meters up, inside a steel box that breathes damp air all night. It spends half its life stopped and cold. It is bolted to a power converter that a 500 V megohmmeter will… Read More: Wind Turbine Insulation Testing: Procedures, IEEE 43 Requirements, and Best… »
Most stator failures are not sudden. They are the end point of a process that has been running for months or years — visible if you know what to look for, detectable by testing before the insulation finally fails in service. Understanding the failure mechanism behind a bad test result is the difference between cleaning a winding and… Read More: Stator Winding Failure Mechanisms: What’s Actually Killing Your Motor »
A generator failure during an emergency is the worst possible time for a generator to fail. Data centers, hospitals, water treatment plants, and utility backup systems all depend on generators that sit idle for months and then must start and carry full load within seconds. Whether they do depends largely on the condition of their insulation — and… Read More: Generator Insulation Testing: A Field Engineer’s Guide »