Schelt Technology

The devices of the HD2001 series…, according to the models, measure temperature, relative humidity, barometric pressure and air speed by hot-wire probes.

All the models are provided with RS232C or RS485 serial output and the management of more than one device connected to a network. In addition, all the models are fitted with an open collector type low-activated configurable alarm output.

The HD2001.1 model has three configurable analog outputs: 4…20 mA or 0…20 mA current output, or 0…10Vdc or 2…10Vdc voltage output. The choice of output type is made by means of the jumpers set on the board.
Wind speed measurement is detected by the HD2001.2 model with a hot-wire probe set on the upper part of the instrument.

The large display with dual indication on all models allows one of the process variables on the first line and the temperature on the second line, to be displayed.

ENVIROsense is our new environmental temperature, relative humidity and, optionally, barometric pressure transmitter series with standard RS485 Modbus-RTU output.
Different versions are available to fully match the specific requirements of different applications:

• Meteorology/Renewable energies: sensor with conformal coating for protection against condensation, contaminants, and salt.
• HVAC/Indoor: cost-efficient for general indoor use.
• Clean Rooms/High performance: for indoor environments when high reliability and robustness are key factors.

Particularly suitable for OEM applications, it can be used in combination with any Modbus-RTU master device via its M12 connector. Two optional additional 0…1 V, 0…5 V or 0…10 V (depending on model) analog outputs, with configurable temperature and relative humidity or dew point ranges.

Transmitters are factory-calibrated in multiple points for relative humidity. Upon request, ISO/IEC 17025 calibration certificate.

Dual relative humidity and temperature transmitter for HVAC applications, environmental monitoring, pharmaceutical storage, food transport, greenhouse automation, etc. Equipped with an IP65 stainless steel AISI 304 housing, it is suitable even for severe environments; besides, its ultra-compact dimensions (Ø 14 x 133 mm) and wide range of outputs (analogue 0…1V, digital RS232C OR RS485-MODBUS RTU, USB 1.1-2.0) make it ideal for integrating into a variety of OEM applications. It is supplied with the HD9817TC software for reading measurements and calibrating the relative humidity sensor.

Following types are available:

HD9817T1R: Dual temperature and relative humidity transmitter. 1/3 DIN Pt100 temperature sensor. Measuring range for relative humidity: 0…100%RH, for temperature: -40…+60°C. Double output signal 0…1Vdc. Power supply 5…35Vdc. Housing made of AISI 304, dimensions Ø 14mm, L= 138mm. Standard configuration 0…100%RH = 0…1Vdc, -40…+60°C = 0…1Vdc. 7-wire cable with shield L = 1.5m.

HD9817T2R: Dual temperature and relative humidity transmitter. Pt100 1/3 DIN temperature sensor. Measuring range for relative humidity: 0…100%RH, for temperature: -40…+60°C. RS232C output. Non-isolated power supply: power supply comes from RS232C PC output. Housing made of AISI 304, dimensions ∅ 14mm, L=138mm. Standard configuration 0…100%RH for relative humidity and -40…+60°C for temperature. Output cable with DB9 female connector, L=2m. Baud rate 2400.

HD9817TVS: Dual humidity and temperature transmitter, Pt100 sensor. 0…1 Vdc analog outputs and RS485 MODBUS-RTU output. Temperature measuring range -40…+60 °C. Power supply 5…30 Vdc. AISI 304 housing. IP 65 probe protection degree. Dimensions ∅14 x 155 mm. Output with 8-pole M12 male connector. Supplied with CP9817.3 cable, length 3 m.

Over 40 years of experience in worldwide applications combined with a new design on accuracy, stability, simplicity and connectivity: this is the HVAC40 series. These transmitters and hygrostats measure temperature, relative humidity and dew point using an interchangeable relative humidity and temperature digital sensor.

The probe is available in three different versions:

• fixed vertical probe for wall mounting
• fixed probe with 2 m cable
• fixed duct horizontal probe

Available outputs, depending on the model:

• RS485 Modbus–RTU digital output
• 0…10 V voltage analog output
• 0…20 mA / 4…20 mA active current analog output
• 2-wire (current loop) 4…20 mA analog output
• ON/OFF relay switch

Relay versions with settable alarm thresholds, hysteresis and delay and supplied as standard with LCD display. Optional LCD for all other versions.

The instruments are factory calibrated and ready for use.

HD48 transmitters are designed for temperature and humidity control in conditioning and ventilation applications (HVAC/BEMS) in the following sectors: pharmacy, museums, clean rooms, ventilation ducts, industrial and civil sectors, crowded places, canteens, auditoria, gyms, high-density farms, greenhouses, etc.

The models of the HD48.. series are active transmitters and accept both direct and 24Vac alternating power supply; they have standard current (4…20mA) or voltage (0…10V) outputs, or a serial RS485 output*, depending on the model.

Available models:

1. horizontal probe for duct mounting (TO),
2. vertical probe for wall mounting (TV),
3. probe with 2 or 5 m cable (TC),
4. fixed contact Pt100 probe for solar panel (TFP)

For the TO and TC versions, two probe temperature ranges are possible: standard -20…+80 °C and extended -40…+150 °C (option E). Temperature range of the thin film 1/3 DIN Pt100 probe for solar panel: -40…+85 °C.

Also available with LCD display (option L). Electronics working temperature: -20…+60 °C.

For Passive Transmitters, please refer to the HD49… series.

Configurable temperature transmitter with output 4…20 mA. Measuring range -200…+650°C, minimum range 25 °C.

Standard configuration 0…100 °C. Electronics operating temperature -20…+70 °C.

Available models:

• HD786TR1 – Container 65 x 58 x 35 mm. Wall mounting, complete with Pt100 probe ∅ 14, L=90 mm.
• HD786TR2 – Container 65 x 58 x 35 mm. Wall mounting, complete with Pt100 probe Ø3, L = 55 mm.

The HD9008…and HD9009… series are single block RH and temperature (or only temperature) microprocessor transmitters, temperature configurable.

They are available in different versions:

• HD9008TRR: 2-wire with 4…20 mA output for RH and temperature
• HD9008T7AC: 2-wire with 4…20 mA output (only temperature)
• HD9008T7S: with RS485 MODBUS-RTU output (only temperature)
• HD9009TRR: 0…1 V standard voltage output (other ouputs available on demand) for RH and temperature

SENSORS
The humidity sensor is a capacitor which dielectric is made up by an hygroscopic polymer.

As water dielectric constant is approximately 80, you’ll get a strong change in capacity as the humidity content of this polymer changes.

The advantages of this kind of sensor are:

• good linearity,
• insensitivity to temperature changes,
• fast response time
• long-lasting life.

Configurable 4…20 mA / 20…4 mA 2-wire temperature transmitter for K, J, T, N thermocouples, minimum amplitude range 50 °C.

Standard configuration: 0…1000 °C, thermocouple type K. Electronics operating temperature -20…+70 °C.

Available models:

• HD978TR1 – in a container for 35 mm DIN rail connection, dimension 1 module.
• HD978TR2 – in a container for 35 mm DIN rail connection, dimension 2 modules, with 3 ½ digit display, figure height 10 mm

The HD3817T… and HD38V17T… are double absolute humidity and temperature active transmitters with 4…20mA current or 0…10Vdc voltage outputs, respectively.

Absolute humidity is the ratio between the mass of water vapour and the measured volume of air, and is expressed in g/m³.

The transmitters of the HD3817T… family may be used in materials humidity control during a drying process. When the materials are dried through heating or a hot air flow, the air absolute humidity increase is directly proportional to the quantity of water lost by the materials. A control system measuring absolute humidity, can maintain a certain humidity level by injecting vapour or water spray in the environment, if needed.

Generally, these transmitters are employed in the chemical, textile, food industry, in the production and storage of paper, in the drying of wood, even with high temperatures and wide humidity excursions.

The type of sensor used is immune to most physical and chemical contaminants. The maximum working temperature is 200°C: This makes these instruments particularly suitable to heavy industrial applications where the traditional capacitive sensor cannot be used.

The response time is fast, as well as the recovery time from saturation.

The maximum measurement ranges are: 0…130 g/m³ for absolute humidity and 0…200°C for temperature: the instruments come out of the factory with the 0…60 g/m³ and 0…200°C standard ranges.

The standard power supply is 24VAC. On request, 115VAC or 230VAC versions are available.

The probe is made of stainless steel and has a 20µm sintered bronze filter. The case is in polycarbonate with an IP66 protection degree.

Active (HD48…) and passive (HD49…) transmitters complete with contact temperature probe for photovoltaic panels with 5 or 10 m cable.

The probe is a round Pt100 sensor Ø 30 x 7.5 mm, 1/3 DIN.

The transmitter is available with following outputs:

• active analogue output 4÷20 mA (HD4807TFP…)
• 0÷10 V output (HD48V07TFP…)
• RS485 MODBUS-RTU output only (HD48S078TFP…)
• passive (2-wire) 4÷20 mA analogue output (HD4907TFP…)

All models can also be supplied with an optional display.

Introducing HD408T and HD4V8T: analog output pressure transmitters designed for monitoring atmospheric pressure.

Ideal for applications requiring monitoring of non-corrosive air or gas, with pressure ranges from 10 mbar to 200 mbar. These transmitters utilize piezoresistive sensors to deliver precise and stable measurements of applied differential pressure, boasting excellent repeatability, low hysteresis, and superior temperature stability.

The output signal of the sensor is conditioned to provide either a current output (HD408T) or a voltage output (HD4V8T), both linearly proportional to the applied differential pressure. Calibrated at the factory, these transmitters are ready for immediate use.

Common applications include monitoring clean room barometric pressure, controlling filters, measuring flows (using Pitot tubes), operating packing and packaging machines, and regulating ventilation systems.

PBS83M… is a series of barometric transmitters belonging to the BAROsense family.

It is equipped with a precision piezo-resistive pressure sensor with integrated temperature sensor. The pressure and temperature measurements are digitally processed to obtain a pressure output value compensated over the whole transmitter temperature operating range.

The transmitter has a digital RS485 output with MODBUS-RTU or proprietary protocol. As option, it can be supplied with an additional analog output, which can be selected by the user in current or voltage via an internal jumper.

The transmitter digital output enables the transmission of the measurements over long distances and connects the transmitter to sensors networks.

Optionally, it can be supplied with additional input for combined temperature and relative humidity probe. Having the external probe connected, the barometric transmitter calculates as well dew point,  absolute humidity and wet bulb temperature.

A user-friendly interface allows to choose from a range of user-selectable units of measurement. An optional LCD display is available for immediate and direct reading of the data.

For outdoor installations, the optional static port with support bracket minimizes measurement errors caused by wind flow, ensuring extreme accuracy and reliability.

Looking for barometric transmitters with only analog output? Have a look at the PBS860…and PBS880… series.

PBS860… and PBS880… are barometric transmitters equipped with a precision temperature-compensated piezo-resistive pressure sensor.

They differ in the measuring range:

• 600…1100 hPa for PBS860;
• 800…1100 hPa for PBS880.

These barometers are tailored for a wide range of applications: from meteorological monitoring to environmental data logging, altitude measurements, barometric pressure compensation in engine performance, cleanroom environments, and vehicle emissions testing.

They operate on low power consumption (< 4 mA), making them the ideal choice for portable, remote, or battery-powered setups, or even solar-powered applications.

With versatile analog output options including 0…1 Vdc, 0…5 Vdc, 0…10 Vdc or 4…20 mA (current loop), you have the flexibility to adapt to diverse environments and requirements

Crafted for durability and reliability, their sturdy polycarbonate housing protection ensures resilience against harsh conditions.

An optional static port with support bracket minimizes the effect of dynamic pressure due to the wind in open field measurements.

Looking for barometric transmitters with digital output? Have a look at the PBS83M… series.

The presence of very pure air, i.e. with a very low content of microparticles of suspended dust, is in some fields mandatory. In the industrial and scientific research and microelectronics industry in general, in the field of bottling and food and moreover in the pharmaceutical field, cleanrooms are used to always ensure a controlled atmosphere.

Especially in these applications, a highly precise and reliable instruments are indispensable for the measurement of differential pressure.

The series of small and compact transmitters HD402xT… is suitable for measuring relative pressure with respect to atmosphere or differential pressure in the range from as low as 0-50 Pa to 0-200 kPa .

The series of pressure ON/OFF relay switches HD402TR…L is suitable for controlling the relative pressure with respect to atmosphere or differential pressure in the range from ±250 Pa to ±200 kPa.
If the set threshold value is exceeded, the relay switch output is activated, the front alarm LED lights up and an audible alarm sounds.

The series of HD404T transmitters is able to measure relative pressures with reference to the atmosphere or differential in the range:

• from 50 to 1000 Pa (from 0.2” H2O to 4” H2O) for the versions with analog output;
• 250 Pa / 1000 Pa / 100 mbar for the versions with RS485 Modbus‑RTU output.

The series uses a silicon “micro‑machined” type sensor compensated in temperature that has an excellent linearity, repeatability and stability over time. The output signal from the sensor is amplified and converted, depending on the model, into a standard current analog output (4-20 mA) and a voltage analog output (0-10 V), or into a digital RS485 Modbus‑RTU output, which, then, can be transmitted over long distances with a high immunity to noise.

In the models with analog output it is possible to choose, via a dip switch, between two measurement ranges in order to select the optimal scale for each application.

Typical applications for HD404… series are:

Clean room monitoring
Filter control
Flow measuring
Air conditioning control
Ventilation control

Usually the low pressure transmitters are susceptible to the guidance by which they are mounted. In HD404T series there is available a special auto-zero circuit, which periodically equalize the differential pressure at the input sensor and corrects the offset; the transmitters, provided with this circuit, are insensitive to the mounting position. In addition, the circuit compensates auto‑zero aging and the deviation of the zero of the sensor to temperature changes: virtually eliminates maintenance.
It’s available the (L) “display” option, in which the pressure is visualized on a display with 4 digits in the selected measurement unit.

The (SR) “square root” is especially useful if the transmitter is connected to a pitot tube, as the output is directly proportional to the speed of airflow.

The transmitters are ready to use and are supplied calibrated by the manufacturer.

Supplied with 1 piece of silicone tubing Ø 5 int./ Ø 8 ext. length 2 m and 2 plastic fittings (HD434T.5).

Active air speed transmitter with omnidirectional hotwire sensor. Probe with wire protection spherical cage Ø 100 mm connected to the electronics via 5 m cable.

Air speed measuring range: 0.1…5 m/s. Outputs for temperature and airspeed.

The transmitter has three configurable analogue outputs: 4…20 mA and 0…20 mA current outputs and 0…10 Vdc voltage output (0…1 Vdc or 0…5 Vdc outputs can be supplied on request). The output can be chosen by using the jumpers inside the instrument.

Power supply 24 Vac (230 Vac on request). Working temperature 0…80 °C.

Sensor working conditions: clean air, RH <80%.

Part number for spare wired protective sphere HD103P.

The HD403TS… series of hotwire air speed transmitters are used for measuring and controlling air speed in ventilation ducts, clean rooms, extractor fans, as well as monitoring air quality (IAQ), etc.

These transmitters are equipped with a hotwire sensor, in the directional or omnidirectional version. The HD403TS… series of transmitters have a 4…20mA output, while the HD4V3TS… series have a 0…10Vdc output.
Two measuring ranges are available: 0.20…40m/s for …S1 and …S3 models with directional probe and 0.08…5.00m/s for …S2 and…S4 models with omnidirectional probe.

List of models:

• HD403TS1: Active hotwire air speed transmitter with output 4…20mA. Range 0.20…40m/s. Directional probe ∅=8mm, 2m cable. Power supply 12…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD4V3TS1: Active hotwire air speed transmitter with output 0…10Vdc. Range 0.20…40m/s. Directional probe ∅=8mm, 2m cable. Power supply 16…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD403TS2: Active hotwire air speed transmitter with output 4…20mA. Range 0.1…5.00m/s. Omnidirectional probe ∅=8mm, 2m cable. Power supply 12…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD4V3TS2: Active hotwire air speed transmitter with output 0…10Vdc. Range 0.1…5.00m/s. Omnidirectional probe ∅=8mm, 2m cable. Power supply 16…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD403TS3: Active hotwire air speed transmitter with output 4…20mA. Range 0.20…40m/s. Directional flexible probe, ∅=8mm, cable L=2m. Power supply 12…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD4V3TS3: Active hotwire air speed transmitter with output 0…10Vdc. Range 0.20…40m/s. Directional flexible probe, ∅=8mm, cable L=2m. Power supply 16…40Vdc or 24Vac. Probe working humidity 5…75%R.H.
• HD403TS4: Active hotwire air speed transmitter with output 4…20mA. Range 0.1…5.00m/s. Omnidirectional probe with protection cage ∅=80mm. Power supply 12…40Vdc or 24Vac. Supplied with VTRAP20 tripod. Probe working humidity 5…75%R.H.
• HD4V3TS4: Active hotwire air speed transmitter with output 0…10Vdc. Range 0.1…5.00m/s. Omnidirectional probe with protection cage ∅=80mm. Power supply 16…40Vdc or 24Vac. Supplied with VTRAP20 tripod. Probe working humidity 5…75%R.H.

Barometric transmitter to wall mount for indoor use, with 0…1 Vdc analog output.

Measuring range 600…1100 mbar. Power supply 10…40 Vdc. Working temperature -30°C… 60°C. Housing dimensions 60 x 66 x 35 mm.

Suitable for installation in the housings for weather stations HD32.35, HD32.35FP, HD32.36 and HD32.36FP.