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2640A/2645A NetDAQ
Users Manual
A-12
2640A 4-Wire Resistance Measurement Specifications A-15.
Tables A-15 to A-17 provide 2640A specifications for the 4-wire resistance
measurement function. The 4-wire measurements use 2 input channels a decade
apart, e.g., channels 4 and 14.
Table A-15. 2640A 4-Wire Resistance Temperature Coefficient
Specification Characteristic
Temperature Coefficient Add 1/10th the 90 day specification per ºC
above 28ºC or below 18ºC.
Accuracy at -20°C Multiply the -10°C to + 60°C accuracy
specification by 2. After 1 hour warmup. For
accuracy between -10°C and -20°C, interpolate
linearly.
Table A-16. 2640A 4-Wire Resistance Range and Resolution Specifications
Resolution
Current Full Scale Maximum voltage
Range
Slow Fast
Applied Voltage applied by instrument
300Ω 1 mΩ 3 mΩ 1 mA 300 mV 3.5V
3 kΩ 10 mΩ 30 mΩ 100 µA 300 mV 3.5V
30 kΩ 100 mΩ 300 mΩ 10 µA 300 mV 3.5V
300 kΩ 1Ω 3Ω 10 µA 3.0V 3.5V
3 MΩ 10Ω 30Ω 1 µA 3.0V 3.5V
Table A-17. 2640A 4-Wire Resistance Accuracy Specifications
Accuracy, 3σ + (% input + V)
18ºC to 28ºC-10ºC to 60ºC
Range
90 Day 1 Year 1 Year
Slow Fast Slow Fast Slow Fast
300Ω .015%+20 mΩ .02%+80 mΩ .02%+50 mΩ .02%+120 mΩ .084%+126 mΩ .084%+336 mΩ
3kΩ .02%+.3Ω .02%+.8Ω .02%+.5Ω .02%+1.2Ω .084%+1.26Ω .084%+3.36Ω
30 kΩ .03%+3Ω .04%+10Ω .03%+5Ω .04%+15Ω .126%+12.6Ω .168%+42Ω
300 kΩ .1%+40Ω . 2%+100Ω .1%+60Ω .2%+150Ω .42%+168Ω .84%+420Ω
3 MΩ* .25%+800Ω* .5%+10kΩ* .25%+1 kΩ*.5%+1.5kΩ* 1.05%+3.36Ω 2.1%+4.2 kΩ*
* The 3 MΩ range is susceptible to the absorption of humidity under extreme conditions. If the instrument is
operated normally within its specified temperature-humidity range, the 3 MΩ range meets its accuracy
specifications. However, if the instrument is “soaked” at 50°C, 90% RH the 3MΩ range may require 1 hour
of “dry-out” time at 25°C, <40% RH for each hour of “soak” time in order to achieve its specified accuracy.