Author Topic: milliOhm meter vs Impeadence analyzer  (Read 615 times)

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Offline R005T3r

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milliOhm meter vs Impeadence analyzer
« on: December 22, 2016, 10:19:13 am »

Recently, I've been interested about milli-Ohm meters, because simply put: DMMs are not able to measure resistance accurately down to the milli/micro ohm range. The bad news is that low ohm values are really susceptible at temperature changes because when things warm up, they increase the resistance, and if you get a decent gear in a properly set up, it will compensate the result value for precision testing.

The point is, I don't understand if milliOhm meters can be replaced with Impeadence analyzer: I know, they surely can measure DC resistance, down to the micro Ohm range, and they can also compensate the temperature. So, what's the deal with having a MilliOhm meter, compared to an Impeadence analyzer (beside, the fact that Impeadence analyzers can measure other parameters?)?  What I'm missing  :-//?

Apparently, also, the test current is much lower with milliOhm meters, and this will prevent the resistance to change.


Offline Gyro

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Re: milliOhm meter vs Impeadence analyzer
« Reply #1 on: December 22, 2016, 10:39:42 am »
Ok, I'll have a stab...

1. Cost. A DC milliometer (or microohmeter) will be a lot cheaper than a full blown impedance analyser.

2. An impedance analyser will measure inductive component as well as resistance. I'm not sure, but I suspect that it will have difficulty in resolving the two (Inductance will probably dominate), which may not be what you want for DC situations.

3. It is sometimes helpful to measure at higher current as it is more representative of actual operation. ie. if the resistance is going to go up at operating current then it's definitely something you want to know about.

Apparently, also, the test current is much lower with milliOhm meters, and this will prevent the resistance to change.
On the contrary, many milliohmmeters are designed to be able to put significant current through the test item, I don't think many impedance analysers do this.

Better quality milliohmmeters cancel thermocouple effects by reversing the test current, pulsing the test current, subtracting thermal emfs between current applications etc.


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