The impulse voltage withstand test fires a short, steep surge across the insulation to see whether it survives the kind of spike that arrives from a lightning strike or a switching event. The waveform is 1.2/50 µs — roughly 1.2 µs to reach peak, 50 µs to fall to half. Here’s the part most write-ups skip. This is… Read More: Impulse Voltage Withstand Test: Clearances and Solid Insulation »
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 »
The DC hipot test is the most consequential offline test you can run on a stator winding. It applies a high DC voltage — well above operating levels — to the groundwall insulation and holds it there. If the insulation fails during the test, you know before the machine goes back into service. If it passes, you have… Read More: DC Hipot Testing of Motor Stator Windings (IEEE 95) »
A hipot tester applies a voltage well above the equipment’s rated operating voltage and watches what happens. If the insulation holds, the equipment passes. If the insulation breaks down, the equipment fails. This sounds simple, but the practical implementation is full of decisions that affect what you can detect, what you can damage, and what your test results… Read More: Hipot Testers Explained: AC vs DC, Withstand vs Breakdown, Safety… »
Switchgear sits at the center of every industrial power system. When it fails, an entire plant, building, or substation goes down. When it fails catastrophically, people can be injured or killed by arc flash. Testing switchgear insulation is one of the highest-leverage electrical maintenance activities you can perform — and one of the most commonly done badly. This… Read More: Switchgear Insulation Testing: The Definitive Field Guide »
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,… »
If you work with electrical equipment internationally, IEC standards govern how you test insulation. But the IEC catalog has dozens of standards that mention insulation testing — and figuring out which one applies to your equipment can be confusing. This guide cuts through the noise. I’ll cover the IEC standards you actually need for insulation testing, with the… Read More: IEC Insulation Testing Standards Explained: A Practical Guide »
Megger testing and hi-pot testing both involve applying high voltage to insulation. Both measure how current behaves through that insulation. And both help you find problems before they cause failures. But they’re not the same test. They serve different purposes, use different voltage levels, and are used at different stages of an equipment’s life. Mixing them up —… Read More: Megger vs Hi-Pot: What’s the Difference? »