User's Guide ______________________________________________________________________
18 __________________________________________________________________ M210855EN-C
-
user friendly, multilingual display
-
calculated output quantities, QFE and QNH, available
-
barometer mounting accessories for multiple installation purposes
-
service port for MI70 Link Interface Software or PC
-
four module slots
-
optional modules: power supply module, RS-485 module, analog
output module and relay module
-
optional USB cable
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IP 65 housing
-
screw terminal, optional M12 connector or D-9 connector
Pressure Measurement
The PTB330 series barometers use a BAROCAP
®
silicon capacitive
absolute pressure sensor developed by Vaisala for barometric pressure
measurement applications. The BAROCAP
®
sensor has excellent
hysteresis and repeatability characteristics, low temperature
dependence and a very good long-term stability. The ruggedness of the
BAROCAP
®
sensor is outstanding and the sensor is resistant to
mechanical and thermal shocks.
The measurement principle of the PTB330 series digital barometers is
based on an advanced RC oscillator and reference capacitors against
which the capacitive pressure sensor is continuously measured. The
microprocessor of the barometer performs compensation for pressure
linearity and temperature dependence.
Table 1
Quantities Measured by PTB330
Quantity
Abbreviation
Pressure (measures average
pressure from P
1
, P
2
, and P
3
)
P
Pressure from barometer
module 1 or 2 or 3
P
1
, P
2
, and P
3
Pressure trend and tendency
P
3h
Pressure difference (P
1
-P
2
) deltaP
12
Pressure difference (P
1
-P
3
) deltaP
13
Pressure difference (P
2
-P
3
) deltaP
23
(available on serial port
only)
QNH pressure
QNH
