VEGA VEGADIF 34 … 51 - Manual (Page 4)

4 VEGADIF 34 … 51
20094-EN-030731
Product description
1 Product description
1.1 Function and configuration
Function
VEGADIF 34 … 51 differential pressure trans-
mitters are an efficient, modular instrument
series for differential pressure, level and flow
measurement.
The sensor element of VEGADIF 34 and 44 is
a single-chamber ceramic measuring cell. It
consists of a disk-shaped ceramic body with
ceramic diaphragms on both sides. Depend-
ing on the acting pressures, the diaphragms
move in or out and the measuring
capacitances change. The difference of the
individual capacitances is reciprocally propor-
tional to the difference of the pressures.
The sensor element of VEGADIF 35, 45 and 51
is a silicon plate with pressure sensitive resis-
tors. The differential pressure to be measured
is received via separating diaphragms and
transmitted to the sensor element via incom-
pressible oil (silicone oil or inert oil). The silicon
plate moves according to the differential pres-
sure. The values of the resistors change
(piezoresistive principle).
The capacitance or resistance values are
detected by the integrated electronics, proc-
essed in the microcomputer and converted
into a 4 … 20 mA output signal. This output
signal is proportional to the difference of the
pressures. Precise, digital processing of
measured data with maximum resolution en-
sures excellent technical data and accuracy.
The electronics in the pressure transmitter
requires a power supply of 11.5 … 45 V DC.
The external power supply is provided via a
separate supply instrument, e.g.:
- power supply unit
(e.g. VEGASTAB 690)
- processing unit with integrated direct volt-
age source (e.g. active PLC input)
- VEGAMET series 500 or 600 signal condi-
tioning instrument, VEGALOG 571 process-
ing system or VEGADIS 371 indicating
instrument
Configuration
Each VEGADIF consists of only two modular
components:
- the electronics housing
- the measuring cell housing.
Sensor-specific data are permanently stored
in an ASIC in the sensor. Hence the measuring
cell modules can be exchanged, e.g. ceramic
for silicon and vice versa. The electronics can
be exchanged, e.g. from 4 … 20 mA standard
to 4 … 20 mA with HART
® communication
protocol, without dismounting the transmitter.