{"product_id":"allen-bradley-1797-tb3-flex-ex-terminal-base-units","title":"Allen-Bradley 1797-TB3 FLEX Ex Terminal Base Units","description":"\u003ch3\u003eDescription\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong\u003e1797-TB3\u003c\/strong\u003e is an intrinsically safe mounting and wiring component functioning within the \u003cstrong\u003eFLEX Ex\u003c\/strong\u003e distributed input\/output platform. This structural device provides the physical termination points for field instrumentation cabling while anchoring individual electronic application modules to a unified backplane cluster. By containing terminal termination paths away from active logic chips, the assembly allows engineers to run physical electrical connections directly within classified process zones without exposing the primary system bus to signal faults.\u003c\/p\u003e\n\u003cp\u003eEquipped with three-tier screw-clamp termination blocks, the unit distributes power, common grounding, and discrete or analog field lines through independent internal channels. The \u003cstrong\u003e1797-TB3\u003c\/strong\u003e links structurally to adjacent base assemblies via an integrated male\/female FlexBus backplane connector, passing data and intrinsically safe power from primary power supplies through the complete multi-module array. It is utilized in heavy extraction and treatment environments—such as marine gas rings, onshore wellheads, chemical storage systems, and grain processing silos—requiring robust mechanical foundations that limit ignition sparks.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eThree-tier screw terminal design separating signal lines, common reference points, and power paths.\u003c\/li\u003e\n\u003cli\u003eIntegrated structural alignment guides supporting modular replacement of application hardware.\u003c\/li\u003e\n\u003cli\u003ePass-through internal FlexBus connection mechanism for clean structural scaling on a single rail.\u003c\/li\u003e\n\u003cli\u003eRugged housing geometry intended for high-vibration industrial installations.\u003c\/li\u003e\n\u003cli\u003eFront-accessible test points simplifying multimeter verification during plant commissioning.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eApplications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eExplosive dust and grain elevator storage management systems.\u003c\/li\u003e\n\u003cli\u003eOffshore natural gas platform processing manifolds.\u003c\/li\u003e\n\u003cli\u003eFuel tank farm telemetry and distribution controls.\u003c\/li\u003e\n\u003cli\u003eHazardous chemical blending and batching facilities.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eSpecification\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer\u003c\/td\u003e\n\u003ctd\u003eRockwell Automation \/ Allen-Bradley\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eFLEX Ex\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003e1797-TB3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eComponent Type\u003c\/td\u003e\n\u003ctd\u003eIntrinsically Safe Terminal Base Unit\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTermination Type\u003c\/td\u003e\n\u003ctd\u003e3-Tier Screw Clamp Terminals\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNumber of Terminal Points\u003c\/td\u003e\n\u003ctd\u003e36\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWire Gauge Capacity\u003c\/td\u003e\n\u003ctd\u003e0.34 mm2 to 2.5 mm2 (22 to 12 AWG) solid or stranded copper\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaximum Voltage Rating\u003c\/td\u003e\n\u003ctd\u003e32V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaximum Current Rating\u003c\/td\u003e\n\u003ctd\u003e2 A per connection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIsolation Barrier\u003c\/td\u003e\n\u003ctd\u003eInternal galvanic and physical safety separations\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e-20 to 60 degC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStorage Temperature\u003c\/td\u003e\n\u003ctd\u003e-40 to 85 degC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelative Humidity\u003c\/td\u003e\n\u003ctd\u003e5% to 95% non-condensing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCountry of Origin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApproximate Weight\u003c\/td\u003e\n\u003ctd\u003e0.25 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApproximate Dimensions\u003c\/td\u003e\n\u003ctd\u003e94 mm x 94 mm x 69 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eConnections\/Interfaces\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eTerminal Row Location\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eTypical Assignment Block\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eRow A (Top Tier)\u003c\/td\u003e\n\u003ctd\u003eInput\/Output Signal 0 through 7 Wiring Nodes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRow B (Middle Tier)\u003c\/td\u003e\n\u003ctd\u003eSourcing Power Distribution Points (Current Limited)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRow C (Bottom Tier)\u003c\/td\u003e\n\u003ctd\u003eCommon Return Reference Nodes and Chassis Ground Links\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eInstallation Guidelines\u003c\/h3\u003e\n\u003ch3\u003eDIN Rail Installation\u003c\/h3\u003e\n\u003cp\u003ePosition the top retention hooks of the assembly over the upper tracking edge of a standard 35 mm DIN rail. Tilt the base downward until the lower metallic tension latch clicks firmly into place onto the bottom track rail.\u003c\/p\u003e\n\u003ch3\u003eBackplane Interconnection\u003c\/h3\u003e\n\u003cp\u003eSlide successive base modules laterally along the DIN rail until the female FlexBus socket of the new unit mates flush with the male pins of the preceding unit. Verify the side-locking tabs engage fully to ensure continuous power path transfer.\u003c\/p\u003e\n\u003ch3\u003eWire Termination\u003c\/h3\u003e\n\u003cp\u003eStrip the insulation on incoming signal leads back approximately 7 mm (0.28 inches). Insert the conductor into the appropriate screw clamp terminal and torque the clamping screw to 0.56 N-m (5.0 lb-in) to prevent loose wire arcing.\u003c\/p\u003e\n\u003ch3\u003eHazardous Area Precautions\u003c\/h3\u003e\n\u003cp\u003eConfirm all connected instrumentation satisfies intrinsically safe energy parameter limits matching the module inserted into the base. Ensure the local enclosure maintains a minimum dust and water ingress protection level appropriate for the target installation zone.\u003c\/p\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the primary function of this structural component?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt serves as the physical mounting foundation and wiring termination interface for operational electronic modules within hazardous zones.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan this unit be utilized with standard non-hazardous 1794 series modules?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, this unit is keyed and engineered exclusively for use with intrinsically safe 1797 series hardware assemblies.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat size wire can be terminated into the screw terminals?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe terminal blocks accept solid or stranded copper wires ranging from 22 AWG up to 12 AWG.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it safe to slide bases apart while the system power supply is turned on?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, isolate input power from the main source before separating base units to prevent interrupting the internal backplane bus.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this base include an integrated communication adapter link?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, it is a passive wiring substrate that relies on a separate network adapter module placed at the front of the rail cluster.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow are the field signals routed into the attached control module?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe electrical pins on the back of the active module plug into the receptacle matrix built directly into the center of the base.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre separate grounding terminal blocks required when using this unit?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe bottom tier provides dedicated chassis ground points designed to link instrument shielding without extra external terminal blocks.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the maximum torque specification for the termination screws?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eTighten all wire clamp screws to a maximum of 0.56 N-m or 5.0 lb-in to ensure a secure low-resistance contact.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan an electronic module be replaced while the field wiring remains attached?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, the terminal base design allows the processing module to be unplugged without disturbing any of the field termination wires.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow many signal connection points are available in total on the unit?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe unit features thirty-six distinct termination screws divided evenly across three separate horizontal rows.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":52695182147947,"sku":"1797-TB3","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0953\/3227\/0443\/files\/allen-bradley-1797-tb3-flex-ex-i-o-terminal-base-module-plc-module-oezmllmcje5_92224a65-04ae-4c6c-ae38-a7c922fe2bf8.jpg?v=1766114330","url":"https:\/\/www.plcprotech.com\/vi\/products\/allen-bradley-1797-tb3-flex-ex-terminal-base-units","provider":"PLC ProTech Ltd.","version":"1.0","type":"link"}