SNAP Analog Input Modules

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16

Thermistor Input Module 0–400 K (continued)

Auto-range Curves

The following table shows temperatures in °C and °F that

correlate with resistance values in Ohms for the generic curve

types for four popular thermistors using the Steinhart-Hart

equation. Choose the curve type for your application in

PAC Control or PAC Manager when you configure a SNAP-

AIR400K-8 module.

Choose a 2-wire thermistor value with a resistance over the

target temperature range that is much larger than the lead

resistance for your application

Lower value curves (2252 or 3K) work best at cooler

temperatures (< 25 °C or 77 °F) because long lead wire

resistance can add significant errors to the measurement.

SNAP-AIR400K-8 Auto-range Curves Table

2252 curve

3K curve

10K type 3 curve

10K type 2 curve

Temp °C

Temp °F

Resistance (Ohms)

-40

-40

75,769.0

100,935.0

239,686.0

336,450.0

-35

-31

54,647.0

72,798.0

179,200.0

242,660.0

-30

-22

39,851.0

53,088.0

135,185.0

176,960.0

-25

-13

29,368.0

39,123.0

102,861.0

130,410.0

-20

-4

21,861.0

29,122.0

78,913.0

97,072.0

-15

5

16,429.0

21,885.0

61,020.0

72,951.0

-10

14

12,459.0

16,598.0

47,543.0

55,326.0

-5

23

9,532.0

12,698.0

37,313.0

42,326.0

0

32

7,353.0

9,795.0

29,490.0

32,650.0

5

41

5,718.0

7,617.0

23,457.0

25,391.0

10

50

4,481.0

5,970.0

18,780.0

19,899.0

15

59

3,538.0

4,713.0

15,130.0

15,711.0

20

68

2,813.0

3,748.0

12,263.0

12,492.0

25

77

2,252.0

3,000.0

10,000.0

10,000.0

30

86

1,814.0

2,417.0

8,194.0

8,057.0

35

95

1,471.0

1,959.0

6,752.0

6,531.0

40

104

1,200.0

1,598.0

5,592.0

5,326.0

45

113

983.8

1,311.0

4,655.0

4,368.0

50

122

811.2

1,081.0

3,893.0

3,602.0

55

131

672.5

895.8

3,271.0

2,986.0

60

140

560.3

746.3

2,760.0

2,488.0

65

149

469.0

624.8

2,339.0

2,083.0

70

158

394.5

525.5

1,990.0

1,752.0

75

167

333.1

443.8

1,700.0

1,479.0