Product Introduction
When designing or upgrading industrial control systems, engineers often face the challenge of integrating field wiring with I/O modules reliably and safely. The ABB TU890 Compact Module Termination Unit (MTU) addresses this need directly. As a passive unit within the S800 I/O family, the TU890 connects field signals and process power to I/O modules while distributing the ModuleBus. Its compact design supports intrinsic safety applications when paired with compatible modules like AI890, AI893, AI895, AO890, AO895, DI890, and DO890. With a maximum rated voltage of 50 V and a maximum current of 2 A per channel, this MTU ensures robust signal integrity for demanding environments.
Technical Specifications Breakdown
The TU890 offers key specifications that matter for system design. It provides 8 channels with a maximum current per I/O channel of 2 A, making it suitable for moderate current loads. The unit operates at 24 V and features a dielectric test voltage of 500 V a.c., ensuring electrical isolation. For wiring, the process connector accepts solid wires from 0.2 to 4 mm² and stranded wires from 0.2 to 2.5 mm² (24–12 AWG), with a recommended torque of 0.5–0.6 Nm. The power supply connector handles 0.25–2.5 mm² (24–14 AWG) with the same torque. These parameters simplify field installation and reduce connection errors.
Industry Applications
In process industries such as chemical plants and refineries, the TU890 excels when used with intrinsic safety I/O modules. For example, in a hazardous area requiring ATEX/IECEx Zone 2 compliance, the TU890 interfaces with Zone 0 modules, maintaining safety without sacrificing performance. Its compact form factor—width 64 mm, depth 58 mm, height 194 mm—allows dense mounting on DIN rails, saving cabinet space. This makes it ideal for retrofitting existing panels or building new distributed control systems where space is at a premium.
Installation & Setup Guidance
Mounting the TU890 is straightforward. It attaches to a standard DIN rail using an integrated latching device, ensuring secure placement. Mechanical keying prevents inserting the wrong module, reducing commissioning errors. For horizontal mounting, the ambient temperature range is 0 to +55 °C; for vertical mounting, derate to 40 °C. Use the recommended torque of 0.5–0.6 Nm for all connections to maintain reliable contact. The 27 blue terminals for process connections are clearly labeled, simplifying wiring verification.
Maintenance & Reliability
Routine maintenance for the TU890 focuses on environmental conditions. The unit operates in pollution degree 2 environments per IEC 60664-1 and offers corrosion protection per ISA-S71.04: G3. With an IP20 protection class, it suits clean indoor installations. Inspect terminals periodically for tightness and check for signs of corrosion or contamination. The MTU’s passive design means no moving parts, contributing to long service life and minimal downtime.
Compatibility & Integration
The TU890 integrates seamlessly with the S800 I/O system, supporting single I/O configurations. It works with AI890, AI893, AI895, AO890, AO895, DI890, and DO890 modules. The MTU distributes the ModuleBus to the I/O module and to the next MTU, enabling daisy-chaining. It also generates correct addresses by shifting outgoing position signals. This compatibility simplifies system expansion and reduces engineering effort.
Selection Guide & Purchasing Advice
Before purchasing the ABB TU890, verify your I/O module compatibility and environmental requirements. The unit is CE marked and carries certifications for hazardous locations (ATEX/IECEx Zone 2, cFMus Class I Div 2) and marine applications (ABS, BV, DNV-GL, LR). Check that your application’s voltage and current demands do not exceed 50 V and 2 A per channel. For current availability and lifecycle status, contact SpareTechPLC, a trusted supplier of industrial automation parts.
Frequently Asked Questions
Q1: Can the TU890 be used with non-intrinsic safety I/O modules?
Yes, the TU890 supports standard S800 I/O modules, but its design also accommodates intrinsic safety modules like AI890 and DI890 for hazardous areas.
Q2: What is the maximum ambient temperature for vertical mounting?
For vertical mounting, the maximum ambient temperature is 40 °C (104 °F), as specified in the detailed data.
Q3: Does the TU890 require a separate power supply?
The MTU itself is passive and receives power through the ModuleBus from the I/O module. It does not require an external power supply.
Q4: How many channels does the TU890 support?
The TU890 provides 8 channels for field signal and process voltage connections.
Q5: Is the TU890 compatible with redundant I/O configurations?
No, the TU890 is designed for single I/O configurations only, as indicated in the detailed data.
