9

®

ISO122

10.0V

Thermocouple

REF

102

27k

Ω

R

1

R

4

+In

–In

–15V

2

14

13

1

R

G

12

10

3

5

4

11

R

5

R

3

R

2

Isothermal

Block with

Ground Loop Through Conduit

100

Zero Adj

R

6

50

Ω

100

Ω

+15V

+15V –15V

+15V –15V

1

2

9

8

16

15

10

7

V

OUT

ISO122P

FIGURE 6. Thermocouple Amplifier with Ground Loop Elimination, Cold Junction Compensation, and Up-scale Burn-out.

SEEBACK

ISA

COEFFICIENT

R

2

R

4

TYPE

MATERIAL

(

(R

Chromel

E

Constantan

58.5

3.48k

Ω

56.2k

Ω

Iron

J

Constantan

50.2

4.12k

Ω

64.9k

Ω

Chromel

K

Alumel

39.4

5.23k

Ω

80.6k

Ω

Copper

T

Constantan

38.0

5.49k

Ω

84.5k

Ω

NOTE: (1) –2.1mV/

°C at 2.00µA.

1M

Ω

INA101

2

6

4

+15V

6

5

RTD

(PT100)

1mA

1mA

2mA

R

–V

0V-5V

+V

Gnd

–V

on PWS740

4-20mA

ISO122P

3

2

14

9

8

2

11

8

7

4

3

V

OUT

10

7

12

4

10

XTR101

+V

on PWS740

R

10

11

5, 13

15

16

15

16

1

FIGURE 7. Isolated 4-20mA Instrument Loop. (RTD shown.)

R

S

RCV420