Vaisala PTU200 - Manual (Page 7)

C HAPTER 2_______________________________________________________ P RODUCT DESCRIPTION
V AISALA __________________________________________________________________________ 3
CHAPTER 2
PRODUCT DESCRIPTION
The PTU200 transmitter combines three measurement parameters:
pressure, temperature and humidity. The applications of the PTU200
range from calibration laboratory environmental condition monitoring
to laser interferometer active wavelength compensation and GPS
meteorological measurements.
The PTU200 transmitters are available with one or two pressure
transducers. Three different kinds of sensor heads can be used with
PTU200: HMP45A-P, HMP45D and Pt100.
The PTU200 transmitters use a RS232 or RS485 (optional) serial
interface and they are available also with a local display.
In outdoor applications, it is recommended to use the PTU200MIK
mounting kit with the PTU200 transmitters. In addition, a mounting
tripod is available to support the PTU200MIK in temporary field
installations.
Pressure measurement
The PTU200 series transmitters use a BAROCAP ® silicon capacitive
absolute sensor developed by Vaisala for barometric pressure
measurement applications. The measurement principle of the PTU200
series digital transmitters is based on an advanced RC oscillator and
three reference capacitors against which the capacitive pressure sensor
and the capacitive temperature compensation sensor are continuously
measured. The microprocessor of the transmitter performs
compensation for pressure linearity and temperature dependence.