IEC 61621 Arc Resistance Test: The 420-Second Ladder Explained
Arc resistance is a stopwatch reading. You put two tungsten electrodes on a flat sample, strike a high-voltage, low-current arc discharge across the surface between them, make the arc progressively nastier every 60 seconds, and write down the second at which the material gives up. That number, in seconds, is the result. The standard sets no universal pass/fail… Read More: IEC 61621 Arc Resistance Test: The 420-Second Ladder Explained »