How to use Thermocouple Transmitters to Monitor Temperatures in Paint Systems Application Note
This document illustrates using Acromag’s TT330 Series to monitor high temperatures in an automotive paint curing oven and transmit to the existing PLC 4-20mA input card/software setup.
Defining the Problem
The area around an auto manufacturer’s paint curing ovens is at elevated temperatures affecting the performance of locally installed instrumentation. Placing Signal Conditioners rated for high operating temperatures near the ovens allows the PLC controlling the process to be mounted in a lower temperature area. The Signal Conditioner will convert Thermocouples to 4–20mA outputs. Running current loops over long distances instead of Thermocouples reduces costs and minimizes the potential for measurement errors due to electrical noise.
An Isolated Thermocouple to Current Signal Conditioner with a high operating temperature, Acromag model TT333-0700, that is rated for –40 to 80°C. The TT333-0700 output powers the loop to the PLC. Also, the plant has standardized on PLCs with less expensive current input cards over temperature input cards. This makes installations and programming throughout the plant more consistent.