HD402T, HD402ST, HD402AT
24
• Sensor with high accuracy and stability
• Measurement of pressures relative to the atmosphere or dierential
pressures
• Dual analog output, current (active or passive) and voltage, or RS485
Modbus-RTU output
• Versions with or without LCD display
Applications
• Control of air conditioning and ventilation
• Control of lters
• Monitoring of clean rooms
• Pneumatic controls
• Respirators
• Vaporizers
Description
The series of transmitters HD402xT... is suitable for measuring relative
pressure with respect to atmosphere or dierential pressure in the range
from as low as 0-50 Pa to 0-200 kPa.
These transmitters use a silicon piezoresistive sensor with high accuracy
and temperature compensation, which has excellent linearity, repeatability
and stability over the time.
The output signal of the sensor is converted, depending on the model,
into a:
• RS485 Modbus–RTU digital output (HD402ST);
• voltage 0...10 V or active current 0...20 mA / 4...20 mA analog output
(HD402T);
• 2-wire (current loop) 4...20 mA analog output (HD402AT).
The output signal can be transmitted over long distances with high
immunity to interference (in the models with analog output the maximum
distance depends on the load and the section of the connection cables,
but distances of several hundred meters are commonly reached).
Dierent units of measurement can be chosen for each model and, in the
models with analog output, it is possible to choose the full scale (f.s.) value
for the output (high, intermediate or low range) and set the unipolar (0 ...
+f.s.) or bipolar (-f.s. ... +f.s.) measuring range.
The conguration can be made through a series of dip switches mounted
on the circuit board or by connecting the serial port of the transmitter to
the PC.
Thanks to the particular sensor used, the transmitters are insensitive to
orientation and position. Moreover, the high stability of the sensor over the
time and in comparison to the changes in temperature allows to eliminate
the operations of maintenance typically required to compensate for the
aging and the deviation of the sensor zero.
The option “display” (L) is available, in this case the values of pressure are
displayed on a 4 digit display under the unit of measure set by the user.
The transmitters are supplied ready for use and factory calibrated in 3
points.
Power supply: 24Vac or 18...40 Vdc for the models with voltage and active
current analog output, 12...30 Vdc for the models with passive current
analog output and for the models with RS485 Modbus RTU output.
Technical specications
Sensor Piezoresistive, High stability
Measuring range
from 0…50 Pa to 0…200 kPa both relative and dierential
(please refer to table 1)
Resolution Please refer to table 2
Accuracy @ 25 °C
± 1.5% f.s. nominal for HD402xT1
± 0.75% f.s. nominal for HD402xT2
± 1% f.s. nominal for HD402xT3, HD402xT4 and HD402xT5
Accuracy @ 0…50 °C
± 3% f.s. nominal for HD402xT1
± 1% f.s. nominal for HD402xT2, HD402xT3, HD402xT4 and
HD402xT5
Long term stability
(1000 h) @ 25 °C
± 0.5% f.s. nominal for HD402xT1 and HD402xT2
± 0.35% f.s. nominal for HD402xT3
± 0.25% f.s. nominal for HD402xT4 and HD402xT5
Output
• HD402T…: Active analog 0…10 Vdc (R
Lmin
= 10 k)) or
0…20 or 4…20 mA (R
Lmax
= 500 )
• HD402AT…: 2-wire (current loop) 4…20 mA (R
Lmax
=
(Vdc-12)/0,022)
• HD402ST…: Digital RS485 Modbus RTU
Response time
Congurable 0.125, 1, 2 or 4 seconds for the output
0.5 seconds for the display updating
Overpressure limit
50 kPa for the models with f.s. up to 10 kPa
200 kPa for the model with f.s. 100 kPa
400 kPa for the model with f.s. 200 kPa
Compatible media Only air and non-aggressive dry gases
Power supply
HD402T…: 24 Vac ± 10% or 18…40 Vdc
HD402AT, HD402ST…: 12…30 Vdc
Absorption
HD402T… and HD402AT…: < 1 W @ 24 Vdc
HD402ST…: < 100 mW @ 12 Vdc
Pressure connection Ø 6.2 mm for tubes with internal Ø 5...6 mm
Electrical
connections
Screw terminal block, max 1.5 mm
2
,
PG9 cable gland for the input cable
Operating conditions -10...+60 °C / 0…95% RH
Storage temperature -20...+70 °C
Housing dimensions 80 x 84 x 44 mm
Protection degree IP65
HD402T HD402ST HD402AT
PRESSURE TRANSMITTERS