On Tuesday, 18 July 2017 22:26:19 UTC+1, Cursitor Doom wrote:
On Mon, 17 Jul 2017 16:50:18 -0700, tabbypurr wrote:

How can they be calibrated when the voltage produced is so unsteady? Or
do they have some form of regulation? I've used very basic cranked
meggers, not those old ones, and the readings were wobbly.

They specify how many RPM you should turn the handle at in the
instructions. Presumably they then have a motor to drive the thing at
that speed in the factory for calibration purposes.
In practice, the output gets progressively less 'wobbly' the faster you
go and they're intended to be spun-up pretty fast. **** knows how they
expect you to judge the specified RPM when taking measurements, though!

Even at constant speed it's going at differing speeds at different parts of the turning cycle. The ones I used had very low handle speed and were far from steady. But they picked up bad insulation ok.


NT