Application Notes

EAP-032139

Detect temperature difference of two T/C sensors

We’d like to measure temperature difference between the inlet and outlet of a heat exchanger by using two T/C sensors. We want to load the inlet-outlet temperature differential with PLC’s DC input card. The PLC can provide 24V power excitation. We also want to display the temp. difference with an appropriate scaling at the field. Do you have any suitable device to meet the application?

We’d like to recommend our 2-wire universal temperature transmitter, model 27HU.

The 27HU can provide a DC output (4-20mADC) in proportion to the temperature difference between two T/Cs. When ordering, please fill in the ordering information sheet and specify “Number of Inputs” as “2” and “Difference”. Each set value is configurable even after you purchase the unit. In this case, please use configurator software, 27HUCFG. You can download this software from our website at free of cost.

As for PC connection, please use Bell 202 modem, COP-H (RS-232-C interface) or COP-HU (USB interface). With this software and modem, for example, you can change the set parameter from “difference temperature” to “average temperature”.

As for temperature difference displaying at field, please use our 2-wire DC panel meter, model 43AL.