Application Notes

EAP-032155

Temperature difference measurement of the heat exchanger

We like to measure the temperature difference of heat exchanger’s inlet and outlet. Output signals from temperature transmitters are 4 to 20mA DC, measured by sensors of 0 to 200°C. We like to measure the temperature difference for the range of -50 to +50°C.

We recommend you to use a 2-input math function module model JF. Select the code 3 of equation for Addition/Subtraction.

X0 = K0 {K1 (X1+A1) + K2 (X2+A2)} + A0
X0: Output, X1: Input 1, X2: Input 2

K1= Input 1 span: temperature/Output span: temperature = 200 °C /100 °C = 2.0
K2= –(Input 2 span: temperature/ Output span: temperature) = –(200 °C /100 °C) = -2.0
A0 = 50% to output as below.
Temperature difference -50°C = 0% output, 0°C = 50% output, +50°C = 100%
Parameters to be specified when ordering, K0 = 1.0, K1 = 2.0, K2 = -2.0, A0 = 50%,
A1 = 0%, A2 = 0%

Using programming unit model PU-2A or PC configurator model JXCON, JF’s parameters can be programmed.