RAD-PT100-4-IFS

105366_en_00

PHOENIX CONTACT

13

3-wire connection method

For long distances between the Pt 100 sensor and the ex-

tension module. To compensate the wire resistances, all

wire resistances must have exactly the same values (R

R

•

Connect the Pt 100 sensor to terminals x.1, x.2, and x.3.

With 3-wire connection technology, the temperature-related

voltage is measured several times. Corresponding calcula-

tions additionally reduce the effect of the cable resistance on

the measurement result. The results are almost as good as

those achieved using 4-wire technology.

The cable resistances R

the same value. This allows you to subtract the established

cable resistance from the measurement result and to get the

Pt 100 platinum resistance value.

Figure 9

3-wire connection method

µC

2.1

2.2

2.3

3.1

3.2

3.3

5.1

5.2

5.3

4.1

4.2

4.3

IO-MAP

0 1

DC

DC

IFS

IFS

A

D

1mA

A

D

1mA

A

D

1mA

A

D

1mA

-I2

-U2

+I2

+I1

-U1

-I1

+I3

-U3

-I3

+I4

-U4

-I4

RL

I+

RTD

ϑ

RL

I–

U–