
71
7 Installation of FLUXUS G709
If the flowmeter has a passive current input, an external power supply is necessary. The
power supply U
H
must be able to
• supply sufficient power for the energy requirements of the passive current source
• cover the voltage drop over the measurement resistance (max. 1 V) and
• cover all other voltage drops (e.g. cable resistance) in the circuit.
A current of min. 20 mA has to be provided.
Connection of an Active Current Source
The terminals
TxA and TxB are on the upper terminal row (x =1...4)
If the polarity of the current source is inversed, only the sign of the measured current will
change.
Fig. 7.10: Connection of an active current source
example:
A passive current source (e.g. a pressure sensor) is connected to a passive
current input.
technical data of the pressure sensor:
auxiliary power supply: U
S
= 11...30 V DC
output signal: I
A
= 4...20 mA
The required auxiliary power supply of the pressure sensor will be calculat-
ed as follows:
U
H min
= U
S min
+ I
A max
· R
mea
+ I
A max
· R
cab
R
mea
- input impedance
R
cab
- cable resistance)
= 11 V + 20 mA · 50
+ 20 mA · 2
= 12.04 V
U
H max
= 30 V (according to specification of the supplier)
Attention!
Never connect an active current source to an active current input!
Attention!
The terminals Txa and Txb must not be connected.
-
+
TxB
TxA
Содержание FLUXUS G704
Страница 4: ......
Страница 174: ...174 UMG70XV3 4EN 12 01 2009 FLUXUS G709 dimensions in mm 198 1 208 25 129 222 2 15 122 5 110 M2 5 43 7 213 129 170 5...
Страница 235: ...UMG70XV3 4EN 12 01 2009 235 D Certificates D Certificates...
Страница 236: ...236 UMG70XV3 4EN 12 01 2009 D Certificates...
Страница 237: ......
Страница 238: ......
Страница 239: ......
Страница 240: ...UMG70XV3 4EN 12 01 2009 D Certificates...
Страница 241: ......
Страница 242: ......
Страница 243: ......
Страница 244: ......
Страница 245: ......
Страница 246: ......
Страница 247: ......
Страница 248: ......
Страница 249: ......
Страница 250: ......
Страница 251: ......
Страница 252: ......
Страница 253: ......
Страница 254: ......
Страница 255: ......
Страница 256: ......
Страница 257: ......