Products > Test Equipment

Measuring 100A DC current

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gaminn:
I have Keithley 2000 or Agilent 34411A. I'm not sure what is their accuracy, also they haven't been calibrated for a long time, but I hope it will be an order of magnitude better than the shunt.

tooki:

--- Quote from: gaminn on June 06, 2024, 08:34:54 pm ---Hi,
occasionally I need to measure current up to 100A DC, which is obviously too much for any handheld multimeter. I found e.g. this shunt https://www.aliexpress.com/item/1005005721758936.html. It promises +- 0.1% accuracy. I would use digital multimeter to read voltage drop accross the shunt (75 mV @ 100A) and then calculate the current. It would be nice if the shunt was 100 mV, then no calculation would be needed....

Is there something better for max 100 USD that can measure 100A +- 200 mA?

--- End quote ---
If you really care about accuracy, do you really think you should be buying from AliExpress?

gaminn:

--- Quote from: tooki on June 07, 2024, 08:40:16 am ---If you really care about accuracy, do you really think you should be buying from AliExpress?

--- End quote ---

That's why I expect 0.2% accuracy from 0.1% Chinese shunt.

nctnico:

--- Quote from: gaminn on June 07, 2024, 07:58:37 am ---Thanks, I will buy that Murata 100A 100mV shunt https://www.digikey.com/en/products/detail/murata-power-solutions-inc/3020-01108-0/3438619, it is quite cheap on Digikey. Hopefully I will be able to screw in some banana sockets (and they will not melt...) instead of that 8-32 screws to make my measurements easier.

--- End quote ---
Personally I'd buy a bigger shunt (like one rated for 200A) if a current of 100A is flowing for longer than a couple of minutes. Otherwise you'll operating it at its limits and it will get quite hot. Also the temperature coefficient may add to much error when a shunt is operated near its power limit.

tooki:

--- Quote from: gaminn on June 07, 2024, 09:08:59 am ---
--- Quote from: tooki on June 07, 2024, 08:40:16 am ---If you really care about accuracy, do you really think you should be buying from AliExpress?

--- End quote ---

That's why I expect 0.2% accuracy from 0.1% Chinese shunt.

--- End quote ---
I like your optimism! :p

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