ABB 3BSC690075R1 TU890 S800 Terminal Unit

ABB TU890 3BSC690075R1 S800 Intrinsic Safety Terminal Unit The ABB TU890 3BSC690075R1, also cataloged as the TU890 Module Termination Unit, operates as a dedicated hardware component for field signal wiring and intrinsically safe galvano-isolation within ABB S800 I/O and System 800xA control platforms. Fitted with 3x9 signal terminal points and an integrated physical wiring separator, the unit distributes power and routes field signals between hazardous-area sensors and backplane Modulebus channels. Hardware Specifications Parameter Specification Model TU890 Brand ABB Part Number 3BSC690075R1 Origin Sweden Dimensions 58.5 mm x 194 mm x 64 mm Weight 0.30 kg Operating Temp +5 to +55 deg C Power Consumption Passive distribution (24 VDC backplane bus feed) Rated Isolation Voltage 50 V Terminal Configuration 3x9 signal terminals Environmental Rating ISA G3 compliant (ISA 71.04) Protection Rating IP20 (IEC 60529) Backplane Bus Communication Velocity and Intrinsic Safety Isolation The TU890 provides galvanically isolated channel routing to prevent transient fault propagation across the backplane, preserving stable backplane bus communication velocity across adjacent S800 I/O slots. Its physical isolation barrier maintains separation between intrinsically safe field wiring and non-intrinsically safe backplane power buses. The design ensures compliance with stringent noise rejection and creepage distance standards, enabling hot-swapping of active S800 I/O modules without interrupting power or communication traffic on neighboring terminal units. Frequently Asked Questions Q: What is the purpose of the physical wiring separator included with the TU890? A: The physical wiring separator maintains a mandatory minimum distance between intrinsically safe field circuit wires and non-intrinsically safe power or communication lines to satisfy hazardous area installation requirements. Q: Can S800 I/O modules installed on the TU890 be hot-swapped under field operating conditions? A: Yes. The TU890 base keeps backplane power and signal circuits intact during module removal, allowing online hot-swapping without disturbing adjacent I/O modules. Field Installation Guidelines Mount the TU890 onto standard 35 mm DIN rails, confirming that rear grounding clips contact unpainted metal surfaces to establish a solid ground reference. Interlock the Modulebus connectors laterally into adjoining S800 terminal bases to complete the backplane communication chain. Insert the included physical wiring separator to physically partition intrinsically safe wiring trunks from standard power lines. Wire field signals to the 3x9 terminal blocks using specified conductor gauges, torque all screw terminals to recommended settings, and ground cable shields directly to the cabinet ground bar.