10
3 Product description
WIKA Operating Instructions - Differential pressure transmitter DPT-10
Interface measurement
1
+
–
h
2
3
Fig. 7: Interface measurement with DPT10
1 DPT10
2 Liquid with higher density
3 Liquid with lower density
A metallic measuring cell is used as sensor element. The process
pressures are transmitted via the separating diaphragms and filling
oils to a piezoresistive measuring element (resistance measuring
bridge in semi-conductor technology).
The difference between the acting pressures changes the bridge volt-
age. This change is measured, further processed and converted into
a corresponding output signal.
1
p
2
p
1
2
3
4
Fig. 8: Configuration metallic measuring cell
1 Measuring element
2 Overload diaphragm/Middle diaphragm
3 Filling oil
4 Separating diaphragms
p
1
, p
2
Process pressures
The markings "+" and "
-
" on the process component in chapter
"
Mounting and connection instructions
" must therefore be noted when
connecting to the process. The pressure acting on "+" goes positive,
the pressure acting on "
-
" goes negative into the calculation of the
pressure difference.
Power is supplied via the H1 Fieldbus. A two-wire cable according to
Fieldbus specification serves as carrier of both power and digital data
for multiple sensors. This cable can be operated in two versions:
•
via an H1 interface card in the control system and additional power
supply
Functional principle
Power supply and bus
communication
