Siemens SITRANS P, Руководство по эксплуатации, Страница: 116 / 280

● Two step linear, square root (VSLN2, for volume or MSLN2, for mass flow)
The loop current has a proportional relationship with the flow rate, two step linear up to
the application point (Page 119).
The square root SLIN2 has a permanently defined application point of 10%. The range up
to this point contains two linear characteristic curve sections. The first section ranges from
the zero point to 0.6% of the output value and 0.6% of the pressure value. The second
section runs at a steeper slope up to the application point at 10% of the output value and 1%
of the pressure value.
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Y Loop current or flow
X Set measuring span
● Two step linear, square root or bidirectional flow measurement (VSL2B, for volume or
MSL2B for mass flow)
For bidirectional flow measurement, enter symmetrical scaling values.
Select a lower scaling value that is symmetrical to the upper scaling value.
Example:
Upper scaling value: 1000 m
3
/s
Lower scaling value: -1000 m
3
/s
The output current in the range of 4 to 20 mA is halved in each case for the forward and
reverse measurements.
– The output current of 4 to 12 mA is used for the reverse measurement.
– The output current of 12 to 20 mA is used for the forward measurement.
Parameter assignment
9.2 Parameter assignment over device with display
SITRANS P320/P420 with 4 to 20 mA/HART
116
Operating Instructions, 11/2019, A5E44852162-AC