[W2CRA] CRA: Looking For . . .

[William Powell]

All,

I'm looking for a contact to a calibration lab or other facility that can provide INEXPENSIVE (free) resistance
measurement to the MICRO ohm (0.000001) or better.

Our new 12 Volt power system will need to measure current in 9 different locations from 1 Amp to 200 Amps.
Measurements will be done with 75 mV (0.075) 300A shunts.  Unfortunately, properly calibrated shunts are +$60.00 each so
we were forced to go with offshore shunts of suspect calibration.
Quick Note: We do NOT need calibration - just accurate resistance measurements for each shunt.  How accurate?  Ohms
opinion  tells us that a 300A, 75 mV shunt should have a resistance of 250 micro Ohms (.075/300 = 0.00025)
A 1 micro Ohm error results in a 1.2 Amp error - not too bad at 200 Amps but crappy when trying to measure 5 Amps.

The objective is to accurately determine the resistance of each of 10 shunts to allow each shunt to be externally
compensated so all 10 shunts provide the same relative accuracy.

Enough techno babble -  Looking  for accurate (repeatable) resistance measurement capability to better  than 1 micro
Ohm, neither for free or at a LOW cost.

Thanks,
Bill - WB1GOT

-- 
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus