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AbTehnic Profesional

Humidity transducer for ducts RKF/A

Humidity transducer for ducts RKF/A

0…100% r.H.
accuracy ±3% r.H.
output 0-10 V, 4-20 mA, changer
heating function for condensation protection
hinge lock technology



Humidity transducer for ducts RKF/A

The RKF/A duct humidity transducer registers the relative humidity 0…100% r.h. of the air in the environment using a capacitive sensor and converts this measured value into a standard output signal 0-10 V respectively 4-20 mA.

As an option the device has a potential-free changeover contact and a backlit display.

The display content can be rotated in 90° steps using a menu and the measured value, the switching threshold set, the state of the respective relay, the MIN/MAX measured values for the selected intervals (1 h / 6 h / 12 h / 24 h) etc. can be read out. In addition the humidity measuring device has a heating function to protect the sensor at high humidity 95…99% r.h.. If the relative humidity exceeds the threshold value set ex-works for a certain period of time the heating function is activated. The sensor is heated for a limited time and thus dried and protected against condensation. During the heating and the subsequent temperature balancing phase the output signal is kept stable at the last measured value before the heating function was triggered.

The humidity sensor is very well protected against contamination by a screwable sintered filter and can, if required, be finely calibrated in situ using an offset controller.


  • Measurement range r.H. 0-100% r.H.
  • Accuracy ±3% r.H. (30%…70% r.H., else ±5% r.H. at 20°C)
  • Temperature dependency ±0,02% r.H. / K (voltage output), ±0,04% r.H. / K (current output)
  • Long term stability ±1%/year
  • Sensor capacitive humidity sensor
  • Sensor protection screwable stainless steel sinter filter, condensation protection by heating function in the range of 95…99% r.H.
  • Flow rate < 2 m/s
  • Supply voltage analog 0-10 V 24 V AC/DC (±5%)
  • Supply voltage analog 4-20 mA 15…36 V DC (Ubmin = 15 V + RLoad*0,02A)
  • Current consumption at 0-10 V typ. 10 mA, 30 mA peak current consumption for 50 ms at switching moment at option relay
  • Current consumption at 4-20 mA max. 20 mA / output, 40 mA peak current consumption for 50 ms at switching moment at option relay
  • Analogue output 0-10 V 3-wire connection, load current < 0,1 mA
  • Analogue output 4-20 mA 2-wire connection (transmitter), max. RLoad(Ohm) = (+Ub – 15 V) / 0,02 A
  • Alarm output 1 x potential-free change-over contact, 48 V, 1 A
  • Switching Hysteresis Relay 2% of the selected scaling (without display), 0,5…5% of the selected scaling adjustable (with display)
  • Electrical connection screw terminals max. 1,5 mm²
  • Housing Polycarbonate PC UL 94 V0 with hinge locks, color signal white similar to RAL 9003
  • Cable gland PG11 high-strength cable gland with strain relief
  • Display optional LCD display with backlight on/off/auto
  • Material Protection tube: stainless steel V2A
  • Dimensions Housing: L 89 x W 80 x H 47 mm, Protection tube: Ø 16 x 190 mm
  • Protection type Housing/electronic: IP65, Sensor: IP30
  • Protection class III
  • Working range r.H. 0…98% r.H. in contaminant-free, non-condensing air
  • Working temperature Probe: -20…+80°C, Electronic: -20…+70°C
  • Storage temperature -20…+50°C
  • Installation mounting flange (in scope of delivery)
  • Approvals CE, EAC, RoHS


SKU Supply voltage Humidity Output r.H. Version Action
RKF/A-I 15…36 V DC 0-100% r.H. 4-20 mA without display
RKF/A-ID 15…36 V DC 0-100% r.H. 4-20 mA with display
RKF/A-IR 15…36 V DC 0-100% r.H. 4-20 mA, changer without display
RKF/A-IRD 15…36 V DC 0-100% r.H. 4-20 mA, changer with display
RKF/A-U 24 V AC/DC 0-100% r.H. 0-10 V without display
RKF/A-UD 24 V AC/DC 0-100% r.H. 0-10 V with display
RKF/A-UR 24 V AC/DC 0-100% r.H. 0-10 V, changer without display
RKF/A-URD 24 V AC/DC 0-100% r.H. 0-10 V, changer with display