Applications
59
The 2000 instruments have an output impedance greater than 10
11
Ω
, thus this
affect is not of importance for unknown values below 1m
Ω
. The following
table gives the uncertainty of the transfer for various values of standard and
unknown resistors. See Note following table.
Table 1: Resistance Values for Transfer
Standard
Unknown
Current
Basic
Uncertainty
Uncertainty With
1ppm + 1
µµ
v Dvm
Stability
100
Ω
10
Ω
20mA
5.75ppm
11.25ppm
10
Ω
100
Ω
20mA
5.75ppm
7.25ppm
1k
Ω
100
Ω
10mA
6.5ppm
8.5ppm
1k
Ω
1k
Ω
10mA
6.5ppm
7.6ppm
10k
Ω
1k
Ω
1mA
6.1ppm
8.1ppm
10k
Ω
10k
Ω
1mA
6.0ppm
7.1ppm
100k
Ω
10k
Ω
100
µ
A
7.5ppm
9.5ppm
100k
Ω
100k
Ω
100
µ
A
6.5ppm
7.6ppm
1m
Ω
100k
Ω
10
µ
A
20ppm
22ppm
1m
Ω
1m
Ω
10
µ
A
10ppm
11.1ppm
10m
Ω
1m
Ω
1
µ
A
137ppm
139ppm
10m
Ω
10m
Ω
1
µ
A
37ppm
38.1ppm
100m
Ω
10m
Ω
0.1
µ
A
1300ppm
1300ppm
100m
Ω
100m
Ω
0.1
µ
A
307ppm
308ppm
Note:
The
Basic Uncertainty
figures in this table are those associated with
the instrument’s stability only, while the overall uncertainty figures are those
including 1ppm + 1
µ
V uncertainty for the voltmeter, which can be achieved
with a high precision DVM, e.g., Hewlett-Packard 3458A. Note also that, in a
standards
laboratory environment, up to 2:1 better uncertainties are readily
attainable from the 2000 instruments.
Summary of Contents for 2000I
Page 1: ...USER GUIDE 2000I 2000M DC Power Source Instruments...
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Page 10: ...10 2000I 2000M User Guide Rev B...
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Page 96: ...2000I 2000M Instrument s User Guide Revision B 96...
