CN-0349

Circuit Note

Rev. 0 | Page 6 of 10

High Range Conductivity Measurements

Table 2 shows the results of the high range measurements, and

Figure 5 shows both the percent relative error of the range and

the percent relative error of the reading. In the high range, from

0.2 mS to 200 mS, the percent error of the reading does not exeed 3%.

Figure 5. Relative Errors in the High Range (from 0.2 mS to 200 mS)

Table 3 shows the results from Table 2, with the resistive offset of

0.1903 Ω corrected. The RR column, corrected in Table 3, is

obtained by subtracting 0.1903 Ω from the RR column in Table 2.

The software (CN-0349 Evaluation Software) can make this

correction. After correction, the 0.2 mS to 200 mS range has a

percent error of less than 1% (see Figure 6).

Figure 6. Relative Errors in the High Range 0.2 mS to 200 mS Measurements

After Correction of the Resistive Offset (0.1903 Ω)

Table 2. High Range,0.2 mS to 200 mS Measurement Data, RFB = 100 Ω, RCAL1 = 100 Ω, and RCAL2 = 1 kΩ

RX (Ω)

YX (mS/cm)

YR (mS/cm)

RR (Ω)

% Error of Range

% Error of Reading

0

∞

5255

0.1903

Not applicable

Not applicable

1

1000.0000

809.4

1.2355

−95.3000

−19.06

5

200.0000

193.9

5.1573

−3.0500

−3.05

10

100.0000

99.1

10.09

−0.4500

−0.90

20

50.0000

49.99

20.00

−0.0050

−0.02

50

20.0000

20.1

49.75

+0.0500

+0.50

100

10.0000

9.99

100.10

−0.0050

−0.10

200

5.0000

5.004

199.84

+0.0020

+0.08

500

2.0000

2.004

499.00

+0.0020

+0.20

1000

1.0000

1.001

999.00

+0.0005

+0.10

1300

0.7692

0.7681

1301.91

−0.0006

−0.15

2210

0.4525

0.4533

2206.04

+0.0004

+0.18

4700

0.2128

0.2116

4725.90

−0.0006

−0.55

6120

0.1634

0.1641

6093.85

+0.0004

+0.43

Table 3. High Range from 0.2 mS to 200 mS with Correction for the Resistive Offset (0.1903 Ω), RFB = 100 Ω, RCAL1 = 100 Ω, and RCAL2 = 1 kΩ

RX (Ω)

YX (mS/cm)

YR (mS/cm)

RR (Ω)

RR (Ω) Corrected

YR (mS/cm)

% Error of Range

% Error of Reading

0

∞

5255

0.1903

0.00

Not applicable

Not applicable

Not applicable

1

1000.00

809.4

1.2355

1.045

956.77

−21.6149

−4.323

5

200.00

193.9

5.1573

4.967

201.33

+0.6644

+0.664

10

100.00

99.1

10.09

9.901

101.00

+0.5024

1.005

20

50.00

49.99

20.00

19.81

50.47

+0.2351

+0.940

50

20.00

20.1

49.75

49.56

20.18

+0.0886

+0.886

100

10.00

9.99

100.10

99.91

10.01

+0.0045

+0.090

200

5.00

5.004

199.84

199.65

5.01

+0.0044

+0.175

500

2.00

2.004

499.00

498.81

2.00

+0.0024

+0.238

1000

1.00

1.001

999.00

998.81

1.00

+0.0006

+0.119

1300

0.7692

0.7681

1301.91

1301.72

0.77

−0.0005

−0.132

2210

0.4525

0.4533

2206.04

2205.85

0.45

+0.0004

+0.188

4700

0.2128

0.2116

4725.90

4725.71

0.21

−0.0006

−0.544

6120

0.1634

0.1641

6093.85

6093.65

0.16

+0.0004

+0.432

1.0

0.5

0

–0.5

–1.0

0

50

100

150

CONDUCTIVITY (mS/cm)

200

–1.5

–2.0

–2.5

–3.0

–3.5

READING ERROR

RANGE ERROR

1.2

1.0

0.8

0.6

0.4

0.2

0

50

100

150

CONDUCTIVITY (mS/cm)

200

0

–0.2

–0.4

–0.6

–0.8

READING ERROR

RANGE ERROR