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Measuring 100A DC current
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AVGresponding:
If "cheap" is the primary operand, I'd buy a couple of hundred of something like these and bin them to get a hundred with the correct values to make a 500W 10mΩ 1% shunt. Also you'd have a hundred spare resistors for your stock afterwards.
nctnico:

--- Quote from: AVGresponding on June 08, 2024, 07:57:55 am ---If "cheap" is the primary operand, I'd buy a couple of hundred of something like these and bin them to get a hundred with the correct values to make a 500W 10mΩ 1% shunt. Also you'd have a hundred spare resistors for your stock afterwards.

--- End quote ---
The self inductance will be too high when using wirewound resistors. Especially if the current is switched off quickly you can get quite high voltage swings. This is already a problem with low inductance, planar resistors at 15A.

Another advantage of using a current shunt over a hall-based current probe is having a high pulse handling ability. So you can measure short pulses to hundreds of amps without needing a current probe which is rated for hundreds of amps (which may also have a higher offset / noise floor).
AVGresponding:
So use a snubber diode or TVS   :-//
trobbins:
AVGresponding, how much is the OP going to pay himself to sort those resistors, and then to construct end terminals and then fit the resistors, then test the one off special ??

A shunt manufacturer has the facilities to test.  The OP doesn't.
nctnico:

--- Quote from: AVGresponding on June 08, 2024, 09:52:22 am ---So use a snubber diode or TVS   :-//

--- End quote ---
That is not the point. The added inductance can influence the circuit you are measuring and/or affect the measurement results.


--- Quote from: trobbins on June 08, 2024, 10:09:43 am ---AVGresponding, how much is the OP going to pay himself to sort those resistors, and then to construct end terminals and then fit the resistors, then test the one off special ??

A shunt manufacturer has the facilities to test.  The OP doesn't.

--- End quote ---
Indeed. And 1 Ohm is low enough for the leads to also have a significant contribution to the resistance. Not to mention the leads won't be made from a low tempco. material.

That is the reason why current shunts have sense terminals as close as possible to the resistive material; to make sure the leads / connections to the load have a minimum impact on the accuracy of a shunt.
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