How can YR1035 be not affected by the inductance of the DUT?

[shapirus]

I have noticed several times that the YR1035 milliohmmeter (which uses a 1 kHz testing signal) displays the actual DC resistance of the conductor under test, which is seemingly not affected by its inductance, which I would expect to manifest itself as an increased value of the displayed resistance with the added part calculated as 2πfL.

I have never taken the time to properly verify it until now. This time I measured the center conductor of a 10 m (or rather about 9.8 m actual) long piece of coax cable:

1. L = 18 µH (measured by ST42 tweezers)
2. Rdc = 0.354 Ω (measured by passing a known DC current and measuring the voltage drop across the wire)

The YR1035 shows 0.355 Ω. No apparent effect of the inductive reactance, which should be about 0.1 Ω at 1 kHz, so the expected reading would be about 0.45 Ω (Rdc + 2πfL).

I have checked the signal across the conductor under test with an oscilloscope. There's lots of background EMI noise, but a 1 kHz wave can actually be seen.

So... What am I missing? How can it display the actual DC resistance even when the measured conductor's inductance is high enough that it can't be ignored?

p.s. ST42 also displays ~350 mΩ regardless of the frequency of the test signal (from 100 Hz to 10 kHz). I guess I'm missing understanding of some fundamental effects here!

[Kleinstein]

There are several ways to suppress the effect of DUT inductance. One is using some square wave and wait a little after the edges. The transition can be relatively fast, as long as the inductance is one small, like in the example.
Another method is measuring the current and voltage in vector voltmeter style (e.g. digitizing and math) and this may get both the resistance and inductance part separate, just like LCR meters do it.

[shapirus]

There are several ways to suppress the effect of DUT inductance. One is using some square wave and wait a little after the edges. The transition can be relatively fast, as long as the inductance is one small, like in the example.
Another method is measuring the current and voltage in vector voltmeter style (e.g. digitizing and math) and this may get both the resistance and inductance part separate, just like LCR meters do it.

Interesting. I will repeat the test later with some larger inductances. Anything larger that I have is wound on cores, though, but I guess that's actually good in this case.