Bertcha's Bench on 11/27/2007
Low resistance measurement of various connectors.
HP Memory Project - Bertcha Bench
HP 4328A Milliohmmeter
Below are two pages from the 4328A manual giving the main specifications of the instrument used for this bench.
| HP 4328A General Information |
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| HP 4328A Specifications |
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HP 4328A Milliohmmeter - At Work
Four Wires input probes shorten.
| HP 4328A Zero Set |
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HP 4328A Milliohmmeter - Calibration Verification
Measuring a 1 milliohm Standard resistor on the 4328A lower range (1milliohm full scale)
| HP 4328A Calibration |
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HP 4328A Milliohmmeter - Test 1
Measuring a 1 meter lenght of 25 mm2 copper wire sample. The measured wire diammeter is 1.8 mm. According to the following calculation the theoretical value would be 7 milliohms.
| HP-Vee Calculation of a 1 meter, 1.8 mm section, copper wire |
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HP 4328A Milliohmmeter - Test 1
Measuring a 1 meter lenght of 25 mm2 copper wire sample. The measured value is 7.4 milliohms. Note that the instrument range switch is on the 10 milliohm full scale position.
| Measured Value of a 1 meter, 1.8 mm section, copper wire = 7.4 milliohms |
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Measuring the submited Samples:
Measurements will be made in the order shown below :
| Connector Samples |
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| Connector Sample A = 430 micro-ohm |
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| Connector Sample B = 1.5 milli-ohm Notice that Range is 3 milliohm FS |
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| Connector Sample C = 625 micro-ohm |
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| Connector Sample D = 860 micro-ohm |
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| Connector Sample E = 18 milli-ohm Notice that Range is 30 milliohm FS ! |
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Summary:
| Connector Samples |
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Residual Resistance of an equivalent
2 cm length of 25 mm2 copper wire |
Final Notes
- Sample A = 0.43 mOhm
- Sample B = 1.5 mOhm
- Sample C = 0.62 mOhm
- Sample D = 0.86 mOhm
- Sample E = 18 mOhm
These measured values are the sum of the contact resistance plus the resistance of the length of material between each end of the contact. If only the contact resistance is to be considered, an approximate value of 200 micro-Ohm could be substracted from every measured values. As shown on the picture on the right this is the residual resistance of a 2cm length of 25 mm2 copper wire, which is itself the approximative length of each tested connector, except connector A. Connector A is only 1cm long, and its diameter is such that the residual resistance of the sample can be considered to be null...
Non mais !