Gas- and Steam Flowcomputer
DigiFlow 515
Operating Manual
28
9.2 Analog inputs
The flow calculator
DigiFlow 515
can be operated with temperature input of Pt100 RTD or with 4-20mA tem-
perature analog current input.
9.2.1 Input of Pt100 RTD
A possibility to measure temperature very exactly offers the four wire Pt100 RTD measurement. (use shielded
wire).
Care must be take that the positive pole of current source connected to positive pole of the signal wires. PTD
himselfs has no polarity.
9.2.2 Analog 4-20mA input
Each 4-20mA input has a load of 120
Ω
. When the computer is AC powerd, there is sufficient current from DC
supply output to power up to 4 transmitters. If more loops are to be powered, an external supply source is
required.
Shielding:
When shielding the input signals, the shield should be connected to earth only at one end.
shield
twisted pair cable
I (+)
I (-)
Signal (+)
Signal (-)
20
21
Signal (+)
Signal (-)
9
10
Pt100
Pt100
2
1
11
12
Pt100_2
Pt100_1
DigiFlow 515
Fig. 7: Connection of the Pt100 RTD
Summary of Contents for digiflow 515
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