J
John S
- Jan 1, 1970
- 0
That's good info. Too low to turn on bipolar junctions.
The 10kHz setting produced 217mV while attached to the primary. Still
low enough.
Unloaded output from the Tonghui:
Hz Vrms
100 288mV
120 287mV
1k 274mV
10k 133mV
Some loading is to be expected. But, still low enough even at no load. Good!
But
what is the last line showing 247 volts and 0.66H?
I think it is due to line wrap with all the >'s building up: Original was...
E(source) V(L) XL(calc) L(calc)
5 3 450 1.2H
3 1.5 350 .92H
.1 .038 247 .66H
[...]
You're welcome. I think this is now outside the Tonghui subject
into the subject of magnetics. The lesson, though, is don't trust
LCR meters with their low excitation to give valid results on
large magnetics.
It looks like you have opened a Pandora's box issue. We need to
learn more why a low-level measurement doesn't work on laminated
cores. What is the mechanism that is causing the discrepancies? Are
there any web links that discuss this in greater detail? Does the
same thing happen on toroids?
All good questions. I have my suspicions, but I'll do some research
before I present them.
This is a very important subject for the Tonghui. If you want to gap
a core, you need to know the inductance you should get after gapping
to confirm it is correct. If the Tonghui can't measure it, I think
we're in trouble.
Well, yes, but not just the Tonghui. This seems to apply to any RLC
instrument that uses low excitation. At least, so it seems for now (Two
in a row). I wouldn't shun further experiments and data.
Thank you,
John S