HUMIDITY PROBES
www.comecogroup.com
Two-wire Relative Humidity Transmitters RHT
♦ Excellent price-to-performance ratio
♦ Temperature compensation system
♦ Built-in two-wire temperature transmitter
♦ Protection at sensor break
♦ High protection class - IP66
The COMECO RHT transmitters measure relative humidity of air and non-aggressive
gases and convert it into standard 4...20mA two-wire current signal. These transmitters use
thin film or solid state sensors, which capacitance changes proportionally to environmental
relative humidity value. All RHT transmitters have a built-in temperature drift compensation
system, which guarantees good stability of measurement. An additional platinum
temperature sensor or second two-wire transmitter may be built-in for measurement of RH
both medium relative humidity and temperature. RHT transmitters are available in three
modifications with different cases, mounting, and temperature ranges. The specific design
of the electronic block allows the user to adjust the output on-site. All this, in addition to the
high environment protection class, the small size, and the low price, make RHT probes
convenient solution for many relative humidity measurement applications.
Technical specifications
Input Accuracy (percents from span)
RH sensor thin film 0 to 100 %RH Measurement error for RH < 2.5 %
RH sensor solid state 5 to 95 %RH Measurement error for T < 0.5 %
Pt100 (w=1.385) (option) -20 to +120 °C Non-linearity within measurement error
Pt500 (w=1.385) (option) -20 to +120 °C Temperature drift (per °C) RH: 0.1%; T: 0.01%
Pt1000 (w=1.385) (option) -20 to +120 °C Power supply
Adjustment of RH - zero (offset) by trimmer ± 20% from span Voltage 8 to 32 VDC
Adjustment of RH - range by trimmer ± 20% from span Admissible variations 1 Vp-p at 50 Hz
Adjustment of T - zero (offset) by trimmer ± 20% from span Max. line load 700 Ω at 24V/20mA
Output Operating conditions (only for the electronic block)
RH current output two-wire: 4 to 20 mA Operating temperature from min. -10 to max. 75 °C
Input range corresponding 0 to 100 %RH Operating humidity 0 to 98 %RH
T current output (option) two-wire: 4 to 20 mA Design and materials
(1)
Input range corresponding min. -20 to max. +120 °C Case material stainless Steel and aluminum
Linearity to measured value Wiring hidden screw terminals
Output current limit max. 23 mA Protection (except sensor) IP66
(1) Exact correspondence is specified by client order within the stated limits
Model A B1 B2 D
365
300
16
5
100
176
COMECO reserves the right of changing specifications without prior notice!
Specification
Sensitive element thin film thin film thin film or solid state (2) thin film or solid state (2)
Medium temperature -10 to 60 °C -10 to 60 °C -10 to 90 °C (3) -20 to 120 °C (3)
Ambient temperature -10 to 60 °C -10 to 60 °C -10 to 60 °C
Weight (without cable) 150 g 170 g 220 g
Mounting on wall in hole (or free mounting) in hole
(2) Contact COMECO for availability!
(3) Please check the RH/T working zone in 'SH' data-sheet!
Ordering code Ä RHT - #1
Code Feature or option Code values
A - for wall mounting, B1 - for mounting in a hole , B2 - for increased temperature,
Variant
D - two-part, for high temperature
#1 Temperature option X - none, D - Pt100, F - Pt500, G - Pt1000, TT - two-wire transmitter
COMECO Ltd. PO Box 378 Plovdiv 4000 Bulgaria; ++359 32- 664749, 621770, fax: 622719; e-mail: info@comeco.org
