Resistance measurements

Chris the retard troll wrote

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Dime a dozen assholes like you make nothing else.

..... Phil

Whooo! You're right about that. Especially them in-can-des-cent ones!! How does putting current through them there things produce both light *and* heat? Amazing!!!

When you get done bombing your trailer for your roach infestation can you favor us with one of your brilliant technical treatises on light bulbs please?

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.

NT

calibration!

The only one I ever used had a slip clutch that you cranked it so fast and it would slip at that point to keep the speed sort of the same. They may have the coils wound in certain ways to help keep the internal voltages porportional to each other. They are not very accurate, nor do they need to be at that high of resistance.

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. Fuck 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

Yup, and as Ralph has already said, they're really not designed for precision accuracy. They tell you only what you really *need* to know and no more and since they are like 60yr old technology, it's not fair to compare them to the currently available stuff anyway.

Same here. Mine gives a reading, but varies somewhat with the crank speed: There's also a leather case and a tangle of wire leads. I just took it for a spin with a handy 22M resistor. Something is wrong as I'm getting very unstable readings. That's not surprising since the insides are filthy. I've been afraid to clean it lest the insulation crumbles.

There are some videos on YouTube mostly showing how to use a Megger.

The technology is quite old and rather crude by todays standards, but still useful for what it was originally intended (measuring high resistances).

On Wed, 19 Jul 2017 00:02:50 -0700, Jeff Liebermann wrote: (...)

"What not to do with a Megger"

-- Jeff Liebermann snipped-for-privacy@cruzio.com

snipped-for-privacy@tubes.com schrieb:

It's for measurement of high resistance values.

hard to read on the scale.

HTH

Reinhard