Brr… It’s cold outside. When it comes to temperature specifications for controllers and I/O, we often scoff of the notion of needing low temperature ratings. But with the below freezing temperatures pushing into South Louisiana, the idea of a low-end “Extreme Temperature” is perhaps no longer extreme. Well at least for a few days.
Normally the ControlLogix platform is rated for 0°C to 60°C (32°F to 140°F). Our usual concern here in the South is the higher end of the temperature spectrum. But what if you needed to meet an even lower operating temperature range?
The Rockwell Automation extreme environment system operates in a broader temperature spectrum, -20°C to 70°C. It is ANSI/ISA2, IEC and EMC- compliant, making it ideal for caustic or extreme environment applications. As part of the Integrated Architecture, the extreme environment system uses the same programming software, network protocol and information capabilities as the standard version, helping to reduce integration costs.
What makes up the extreme environment system? It’s the ControlLogix-XT and Flex I/O-XT products.
Darker gray in color than standard Allen-Bradley products, the Rockwell Automation extreme environment system spaces modules in every other slot for thermal cushion/isolation and offers redesigned ventilation for increased air flow. The following catalog numbers are available with the “XT” designation, and meet the extreme temperature specifications.
- Controller, catalog number 1756-L63XT, -L73XT, -L73SXT, -L7SPXT
- Redundancy Module, catalog number 1756-RM2XT
- Communications, catalog numbers 1756-CN2RXT, -EN2TXT, -EN2TRXT, -DHRIOXT
- Power Supply, catalog number 1756-PAXT, -PBXT
- Chassis, catalog number 1756-A5XT, -A7XT
- Slot filler, 1756-N2XT
When it come to I/O for extreme temperatures, the Flex I/O-XT would be used. The following catalog numbers are available with the “XT” designation, and meet the extreme temperature specifications.
- Digital I/O, catalog numbers 1794-IB16XT, -OB16PXT, -OB8EPXT, -IB10XOB6XT, -OW8XT
- Analog I/O, catalog numbers 1794-IE8XT, -IE4XOE2XT, -IF4IXT, -IF8IHNFXT, -IF2XOF21XT, -OE4XT, -OF4IXT
- Specialty I/O, catalog numbers 1794-IRT8XT, -IJ2XT
- Communications, catalog number 1794-ACNR15XT, -AENTRXT
- Terminal bases, 1794-TB3, -TB3S, -TB3SK, -TB3G, -TB3GS, -TB3GSK, -TB3T, -TB3TK, -TB3TS, -TB3TSK-TBN1, -TB3K, -TB3GK, -TB32, -TB32S, -TBNK
Note that there is no Extended Temperature Flex Power Supply available. The standard Flex Power Supplies, 1794-PS13 and 1794-PS3, can NOT be used. One recommendation is to use either the Allen-Bradley 1607-XT50D1A or 1607-XT100D1A ArmorPowerTM On-MachineTM Power Supplies.
Using the Logix-XT Products
ControlLogix-XT system components are rated for extreme environmental conditions only when used properly with other Logix-XT system components. The use of ControlLogix-XT components with traditional ControlLogix system components nullifies
extreme-environment ratings. For example, if a 1756-EN2TXT module is used in a standard 1756-A10 chassis, the 1756-EN2TXT module can withstand only the environment specified for the traditional 1756-EN2T module.
What is the difference between the XT version and the LXT version of an extended temperature ControlLogix chassis?
In the circumstance where you need the lower temperature specification (down to -25°C), but not the higher end, then the LXT chassis can be used.
- The XT range ControlLogix-XT™ chassis is a fully extended temperature range chassis (-25°C to +70°C) and comes with the air gaps/spaces (dark grey plastic placeholders with ventilation openings) installed out of the box. The spaces allow the modules to dissipate their heat.
- The LXT range (L for low) ControlLogix-XT™ chassis is to be used in applications where the low temperatures (down to -25°C) of ControlLogix-XT are needed, but no high-temperature demands are placed on the system (max. +60C as the non-XT chassis). There are no air gaps/spaces installed as they are not required.