Farmers Grain Terminal’s headquarters elevator and river terminal in Greenville, MS (662-332-0987), has relied for years on a conventional analog-type grain temperature monitoring system utilizing thermocouple cables inside grain tanks to monitor grain quality in storage.
“We were wanting to upgrade our system,” says Kevin Green, operations manager for the Delta regional cooperative. “The cables were subject to damage due to water seepage or lightning strikes. Also, it was getting harder to find anyone with the skills to do maintenance and repair on the system.”
In addition, the system was set up to take a reading from all of the cables in every tank once a day, supplying data to a computer workstation. Hot spots inside stored grain indicating the potential for molds or insect infestations often develop faster than that.
Farmers Grain Terminal in 2020 turned to its automation contractor, C.A. Technologies, Greenville (662-335-5085), to devise an upgrade to its grain temperature monitoring system.
Rather than select and install a completely new system, C.A. Technologies recommended upgrading the existing system utilizing a BusMux Pro HD multiplexer from EXTRON AgTECT, Minneapolis, MN (763-544-4197).
The BusMux Pro reads signals from standard thermocouples and downloads that data to Farmers Grain Terminal’s PLC system. Because BusMux Pro is used in conjunction with EXTRON Smart Sensor Technology, the user can be sure the temperature data comes directly from the sensing point and not some junction created somewhere in the circuitry. Data can be transmitted via standard wire circuitry or wirelessly.
Rather than once a day, the BusMux Pro reads data from all of the thermocouple cables throughout the Greenville elevator in less than a minute. This allows the user to monitor temperature trends in the tanks on a near real-time basis.
Several alarms to alert users can be programmed in:
• Temperature. This input card reads the raw value from each connected sensor on the cable.
• Resistance. This measures the electrical resistance of the cable and sensors to determine if they are operational.
• Open sensor. This determines if a sensor has a high resistance or the connection is broken.
• Rate of rise. This measures a temperature change over time and sounds an alarm if that rate exceeds a set point.
• Shorted sensor. If resistance drops below a set point, the senor is considered shorted and the user alerted.
In addition to grain temperature monitoring systems, the BusMux Pro can be used for hazard monitoring including monitoring rub blocks and bearing sensors.
Green comments that the cooperative plans to upgrade temperature systems at its other elevators over time.
Ed Zdrojewski, editor
From May/June Grain Journal 2021