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I need measure a 10A AC current, and need a 50mOhm current sensing resistor with tolerance <= 1% and good temperature stability. I find there are some choices, such as Vishay's RH,NH series, or this type made by special copper alloy as below:

enter image description here

Which one is better? Any other suggestions?

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  • \$\begingroup\$ 50mOhm will dissipate almost 5A at full current. Do you need that value because of the amplifier you are using? \$\endgroup\$
    – Krunal Desai
    Commented Jan 12, 2016 at 3:15
  • \$\begingroup\$ @gbulmter - 50 mOhm is 0.05 Ohms so it will dissipate 5 watts with 10 amperes through it. \$\endgroup\$
    – Barry
    Commented Jan 12, 2016 at 3:26
  • \$\begingroup\$ What do you mean by "better"? You need to give some clues, either the use-case, or the constraints. Also I can't open the link topresistor.com/wp-content/uploads/2013/07/FL.pdf Please give enough information to track the part down (manufacturer and part number). \$\endgroup\$
    – gbulmer
    Commented Jan 12, 2016 at 3:28
  • \$\begingroup\$ Whoops yeah, on mobile, meant power. IMO I'd revisit the analog solution as a 50mOhm resistor is 100*0.05 or 5W dissipated which is a lot. Maybe improving gain or changing parts could help, but need to know more. \$\endgroup\$
    – Krunal Desai
    Commented Jan 12, 2016 at 3:30
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    \$\begingroup\$ ecee.colorado.edu/~ecen4517/components/parts/OAR.pdf \$\endgroup\$
    – Anke Ge
    Commented Jan 12, 2016 at 3:36

2 Answers 2

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The "RN, RH" are wirewound with no hint about inductance, so depending on your use case, they might be unusable.

I can't open the link for http://www.topresistor.com/wp-content/uploads/2013/07/FL.pdf so it may be no use either.

I would have expected something like 50mΩ ±1.0% 7W SMD or 50mΩ 1% 5W through hole, designed to be low-inductance current shunts, which specify inductance.

Maybe a lower resistance to reduce power loss.

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Why not look at a current transformer if you have the space and want to save power.Otherwise you could look at a hall effect device .The hall effect devices are now much cheaper and a bit smaller . If you must use a shunt then materials like Manganon or Constantine have good temp stability.

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  • \$\begingroup\$ Manganin (Cu86Mn12Ni2) and Constantan (Cu55Ni45). \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Jan 12, 2016 at 8:46
  • \$\begingroup\$ @ Spehro Pethany I will try to spell .I had spelled the alloys the way others pronounced them .My screen name is not without an element of truth . \$\endgroup\$
    – Autistic
    Commented Jan 12, 2016 at 9:27

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