RAFT/A Humidity / Temperature Transducer

What it measures and how it outputs

The RAFT/A picks up the temperature of the ambient air and, as an option, relative humidity, absolute humidity, mixing ratio or dew point. The measured value is delivered as a linear 0-10 V or 4-20 mA output signal.

It can be fitted with a potential-free changeover contact, assignable to either of the two measured values, and with a backlit display. Through a menu, the display content rotates in 90° steps and shows the measured value, the configured switching threshold, the relay state, the MIN/MAX values for the chosen intervals (1 h / 6 h / 12 h / 24 h) and more. The second variable, besides temperature, is picked by DIP switch from 4 parameters: % RH, g/m³, g/kg and dp.

Heating against condensation

At very high humidity (95...99% RH), a heating function protects the sensor. If relative humidity stays above the factory-set threshold for more than 10 minutes, the sensor is heated for a limited time, dried and kept free of condensation. Throughout heating and the temperature balancing phase that follows, the output holds the last value measured before heating started.

A screw-on sintered filter keeps contamination away from the sensor very effectively, and an offset controller allows fine calibration on site when needed.

Specifications

• RH range: 0-100% RH
• Absolute humidity: 0-50 g/m³, 0-80 g/m³ (calculated), set by DIP switch
• Mixing ratio: 0-50 g/kg, 0-80 g/kg (calculated), set by DIP switch
• Dew point: -20...+50°C DP, -20...+80°C DP, 0...+50°C DP (calculated), set by DIP switch
• Temperature: -30...+70°C, -20...+80°C, 0...+50°C, 0...+100°C, set by DIP switch
• Humidity accuracy: ±3% RH (within 30-70% RH; otherwise ±5% RH, at 20°C)
• Temperature accuracy: ±0.5 K
• Temperature influence: ±0.02% RH / K (voltage output), ±0.04% RH / K (current version); ±0.05°C / 10 K (voltage version), ±0.07°C / 10 K (current output)
• Long-term drift: ±1%/year
• Sensing element: combined electronic humidity and temperature sensor
• Sensor protection: screw-on stainless steel sintered filter, plus anti-condensation heating in the 95...99% RH band
• Air velocity: < 2 m/s
• Supply, 0-10 V analog version: 24 V AC/DC (±5%)
• Supply, 4-20 mA analog version: 15...36 V DC (Ubmin = 15 V + RLoad*0.02A)
• Consumption at 0-10 V: 10 mA typical, with 30 mA peaks for 50 ms when the optional relay switches
• Consumption at 4-20 mA: max. 20 mA / output, with 40 mA peaks for 50 ms when the optional relay switches
• 0-10 V output: 3-wire, load current < 0.1 mA
• 4-20 mA output: 2-wire (transmitter), max. RLoad(Ohm) = (+Ub - 15 V) / 0.02 A
• Alarm: 1 x potential-free changeover contact, 48 V, 1 A
• Relay switching hysteresis: 2% of the selected scale (without display); 0.5...5% of the selected scale, adjustable (with display)
• Wiring: screw terminals, max. 1.5 mm²
• Enclosure: polycarbonate PC UL 94 V0 with hinged locks, signal white similar to RAL 9003
• Cable gland: high-strength PG11 with strain relief
• Display: optional LCD with backlight on/off/auto
• Protection tube: stainless steel V2A
• Size: enclosure L 89 x W 80 x H 47 mm; protection tube Ø 16 x 40 mm
• Ingress protection: enclosure/electronics IP65, sensor IP30
• Protection class: III
• RH working range: 0...98% RH in clean, non-condensing air
• Working temperature: probe -20...+80°C, electronics -20...+70°C
• Storage temperature: -20...+50°C
• Mounting: screw fixing
• Approvals: CE, EAC, RoHS