You meggered a motor. The display says 12 MΩ. Now what? Almost everyone in the field carries the same number in their head: one megohm. Anything above 1 MΩ, energise it. That rule is older than most of the motors it gets applied to, and for a modern machine it is far too generous. IEEE 43-2013 — the… Read More: Motor Megger Value: What Reading Is Acceptable? »
A megohmmeter puts 500 to 5,000 V onto whatever you connect it to. That’s the part people forget. It’s a test instrument, but it’s also a small high-voltage source with a capacitive load hanging off the end of it. The instrument work is simple. Isolate, select a voltage, connect, hold, read, discharge. What separates a clean test from… Read More: How to Use a Megohmmeter: Setup, Test, and Safe Discharge »
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? »
A megger test on a motor takes about five minutes. Reading the result correctly takes a bit more than that. The number on the display means nothing on its own. A 50 MΩ reading is fine on a 6.6 kV machine and a warning sign on a 400 V one. Temperature moves it. Humidity moves it. A dirty… Read More: How to Megger a Motor: Steps, Voltages, and Good Readings »