The TU818 is a 32-channel compact Module Termination Unit (MTU) designed for ABB's S800 I/O system, suitable for industrial automation and process control applications up to 50V. As a passive interface unit, the TU818 reliably connects field signal wiring to S800 I/O modules. It incorporates part of the ModuleBus, providing power distribution, communication, and address assignment functionality to the I/O modules. Its compact design, flexible installation, and easy configuration make it widely applicable in automation control systems across industries such as power generation, chemicals, manufacturing, and marine.
The TU818 is compatible with a variety of S800 series I/O modules, including AI810, AI815, AI835A, AI843, AI845, AI880A, DI810, DI811, DI818, DI830, DI831, DI840, DI880, DI885, DO818, and DP840, offering users a high-density, highly reliable signal termination solution.
2. Key Features
Compact Design
The TU818 features a highly integrated structure with a width of only 64mm (including connectors). It supports connections for up to 32 channels of signals and process power in space-constrained environments, ideal for high-density installations.
Flexible Wiring Options
Supports one-wire or two-wire connections (depending on the connected I/O module type). The screw-clamp terminals accommodate solid wires with a cross-section of 0.5–2.5 mm² or stranded wires of 0.5–1.5 mm².
Mechanical Keying for Mistake Prevention
Equipped with a dual mechanical keying system. Each key has six positions, allowing for a total of 36 different mechanical combinations. This effectively prevents the insertion of incorrect I/O module types, enhancing system safety.
ModuleBus Integration and Address Assignment
The MTU not only distributes the ModuleBus signals to connected I/O modules but also automatically generates module addresses by shifting position signals, simplifying system configuration and commissioning.
Reliable Mounting and Locking Mechanism
Designed for standard DIN rail mounting with an integrated mechanical latch, ensuring secure grounding and preventing accidental dislodgment. A locking mechanism secures the I/O module in place and sends a "BLOCK" signal to the module, keeping it in its initialization state until fully locked.
High Maintainability
The terminal block is divided into two independently isolated groups, each with 16 channels. The top cover is removable, allowing for replacement of the terminal board even while the system is operational, facilitating quick maintenance in cases such as damaged terminal screws.
3. Mechanical and Electrical Structure
Mechanical Structure
Enclosure and Protection: Protection rating IP20 (IEC 60529), suitable for installation inside indoor control cabinets.
Mounting: Standard DIN rail mounting, suitable for both horizontal and vertical orientations (ambient temperature must not exceed 40°C for vertical mounting).
Locking Design: Features a mechanical latch that can be easily engaged or released using a screwdriver.
Terminal Layout: 40-pole screw terminal block, arranged in two rows of 20 positions each, corresponding to 32 I/O channels and 2 sets of process power connections (L1+/L1-, L2+/L2-).
Electrical Structure
Channel Isolation: Signal terminals are divided into two groups, each with 16 channels, providing electrical isolation between groups for improved noise immunity.
ModuleBus Distribution: Includes a ModuleBus interface providing 5V and 24V power to I/O modules, with a maximum current of 1.5A each.
Process Power Connections: Supports two independent process power inputs/outputs, each with a maximum continuous current of 8A.
4. System Integration and Applications
As a key component of the ABB Ability™ System 800xA® hardware platform, the TU818 integrates seamlessly with the S800 series I/O modules to build highly reliable, scalable distributed I/O systems. It is suitable for the following typical application scenarios:
Process Automation: Signal acquisition and control in industries like chemicals, oil, and gas.
Power Monitoring: Analog and digital signal processing in substations and power plants.
Manufacturing Execution Systems (MES): Status monitoring and control of production line equipment.
Marine and Offshore Engineering: Certified by classification societies such as ABS, BV, DNV-GL, and LR, making it suitable for ship control systems.
Environmental Control: Signal interfacing for Building Automation and HVAC systems.
5. Installation and Maintenance Guidelines
Pre-Installation Check
Verify that the mechanical key configuration matches the intended I/O module type. Inspect terminal screws for integrity.
Wiring Standards
Use wires within the specified cross-sectional area. Tighten screws to the recommended torque, avoiding exposed strands or wire damage.
Grounding and Insulation
Ensure the DIN rail is properly grounded, complying with IEC 61140 Class II equipment protection requirements.
In-Service Maintenance
If the terminal board needs replacement, the top cover can be removed without system power-down, allowing maintenance without interrupting operation.
6. Safety and Compliance Statement
The TU818 complies with numerous international safety and environmental standards, including CE marking, ATEX Zone 2 for hazardous locations, and major marine classification society certifications, ensuring its reliability and compliance in demanding industrial environments. The device design meets IEC/EN 61131-2 mechanical operating conditions, making it suitable for industrial automation control systems.
