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Doc.-no.: PFT_01_EN Issue: 05/2017
2. Product description
Our PFT are combined measuring transducers for the measurement of rel. humidity and
temperature.
Special features of the individual devices:
PRODUCT DESCRIPTION
For the application areas of sewer / pipe systems, indoor area or in the outdoor and wet
area, we provide various special designed housings.
Our PFT22 and PFT25 are both designed as two-wire technology with two output signals
of 4...20 mA or as three-wire technology with two outputs of 0...10V. The supply voltage
of the two-wire technology is 15...30 Vdc, in three-wire technology it is 24 Vdc or 24Vac.
As PFT28 it is supplied with 15...30Vdc or 24 Vac, with a jumper the output signals can be
switched from 0/2...10 V to 0/4...20 mA.
2.1 Intended use
The combined transducers of the PFT series are used for measuring / signal transmission
of relative humidity and temperature in the application area of heating and air-conditioning.
2.2 Functional description
Our PFT devices are equipped with a single-chip sensor for an optimal measurement of
relative humidity and temperature. Depending on the application the sensor chip is located
in a stainless steel probe tube or is housed directly in an ABS plastic housing.The signi-
cant parts of sensors are: Two sensor units (capacitive measuring principle for relative
humidity and semiconductor principle for temperature), a signal amplication, a 14-bit
A / D converter and a digital two-wire interface. Furthermore, there is a OTP memory
located on this chip, which stores the calibration data of both capturing principles. The
signal transmission from sensor to evaluation electronics takes place digitally.The sensor
- Two analog outputs:
1.Temperature -30...+50 °C
2. relative humidity, dew point temperature, enthalpy;
Special version: Absolute humidity
PFT25
- Two analog outputs:
1.Temperature with four switchables measuring ranges
2. relative humidity.
PFT22
- Display
- Selectable analog output: 0/2...10 V or 0/4...20 mA
- Two analog outputs:
1.Temperature -30...+50 °C
2. relative humidity, dew point temperature, enthalpy;
Special version: Absolute humidity
PFT28
