Rievtech ELC Series - Page 192

EN
Programmable Relay ● User Manual for ELC, EXM and PR Series 192 2020 v6.0 ● © Rievtech Co.,
Ltd. ● www.rievtech.com
RH Math
Description of function
This block is used to calculate the Relative Humidity given
the Wet and Dry bulb temperatures. For the calculation,
the pressure is assumed to be 101.3 kPa (Kilopascals) or 1
Atmosphere. If required, this value can be changed to
another or can be changed by refencing another block.
Connection
Description
Input Ax (Tdry)
( )
The analogue input signal of the
Dry temperature. (0 – 10 V
corresponds to 0 – 1000 internal
PLC values).
Input Ay (Twet)
( )
The analogue input signal of the
Wet temperature. (0 – 10 V
corresponds to 0 – 1000 internal
PLC values).
Parameter
The pressure at which the
temperatures are measured.
Default is 1 Atmosphere (101.3
kPa). This value is changeable to
a fixed value or variable if
referenced to another block.
Output AQ
The calculated Relative Humidity.
Range of AQ is -32,768 to 32,767
Example
With a measured Dry temperature of 23 °C and Wet
temperature of 14 °C at 101.3 kPa gives a Relative
Humidity of 35%.