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measuring mA AC using uC
hussamaldean:
Hi all
I am currently working on AC power analyzer. However, I am using ACS7212-30A which can't measure less than 1mA and I want to measure as low as 1mA
is there any way to measure such current? like using current transformer or current shunt resistance?
regards
cur8xgo:
--- Quote from: hussamaldean on June 04, 2019, 02:59:02 pm ---Hi all
I am currently working on AC power analyzer. However, I am using ACS7212-30A which can't measure less than 1mA and I want to measure as low as 1mA
is there any way to measure such current? like using current transformer or current shunt resistance?
regards
--- End quote ---
Well certainly a shunt resistance would get you there assuming you can measure the voltage across it at 1ma and you can reference it in a way that doesn't cause issues.
At the extreme end you could think about the small voltage across a small shunt resistance as a thermocouple voltage and look at techniques used to measure those.
hussamaldean:
--- Quote from: cur8xgo on June 04, 2019, 06:22:17 pm ---
--- Quote from: hussamaldean on June 04, 2019, 02:59:02 pm ---Hi all
I am currently working on AC power analyzer. However, I am using ACS7212-30A which can't measure less than 1mA and I want to measure as low as 1mA
is there any way to measure such current? like using current transformer or current shunt resistance?
regards
--- End quote ---
Well certainly a shunt resistance would get you there assuming you can measure the voltage across it at 1ma and you can reference it in a way that doesn't cause issues.
At the extreme end you could think about the small voltage across a small shunt resistance as a thermocouple voltage and look at techniques used to measure those.
--- End quote ---
thinking about using 1Ohm 1Watt resistor and short it when I need more current like using relay or something similar
Kleinstein:
For AC one can use a current transformer if needed also for small currents. It gives insulation from the measurement circuit, which can be a big help.
A shunt is also possible - usually one would have something like 10 -200 mV as the maximum voltage at the shunt. So a 1 Ohms resistor would be Ok up to about some 200 mA. With AC one can do amplification relatively easy, as there are less offset problems. So less voltage may be acceptable with AC than with DC. Also AC accuracy is usually not that good anyway.
For the 1 ohms shunt one could use diodes in parallel to protect it from too much power / current.
hussamaldean:
--- Quote from: Kleinstein on June 04, 2019, 06:57:36 pm ---For AC one can use a current transformer if needed also for small currents. It gives insulation from the measurement circuit, which can be a big help.
A shunt is also possible - usually one would have something like 10 -200 mV as the maximum voltage at the shunt. So a 1 Ohms resistor would be Ok up to about some 200 mA. With AC one can do amplification relatively easy, as there are less offset problems. So less voltage may be acceptable with AC than with DC. Also AC accuracy is usually not that good anyway.
For the 1 ohms shunt one could use diodes in parallel to protect it from too much power / current.
--- End quote ---
I will buy 100A current meter which commonly designed for control panels which comes with current transformer
what value of resistance shall I use for 1Amp range,10Amp and 100Amp range ?
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