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Myth or Reality? I can measure inrush with min/max.

I can measure inrush with min/max.

First, what's inrush again? It's the surge of current draw at motor startup. Newer, high-efficiency motors draw significant inrush current, enough to affect circuit loading (and cause voltage drops) if you don't account for it. Knowing the inrush value can also be important during motor troubleshooting.

While min/max, peak, peak/hold and so forth do capture readings that are higher than regular running current, they don't take the measurement at the exact moment of motor start and are therefore not be accurate.

To provide repeat-ably accurate inrush measurement, your meter needs a trigger mode that synchronizes with the starting current. The Fluke 330 series clamp meters has a mode like this. Once triggered, it takes a large number of samples during a 100 millisecond period and then digitally filters and processes the samples to calculate the actual inrush current.

For more information, Fluke has an application note on inrush current (.pdf) »