ABB 3BDH000378R0001 TU715F Freelance S700 I/O Terminal Unit

Product Overview

The ABB 3BDH000378R0001 (Model: TU715F) is a rugged, passive **I/O Terminal Unit Base** developed for the S700 Remote I/O System within the ABB Freelance Distributed Control System (DCS) framework. It serves as the physical mounting foundation and field wiring interface for S700 electronic input/output modules. Featuring high-durability screw-type terminals, the TU715F handles a high common-mode voltage rating of 24 VDC and an impressive cumulative current load capacity of up to 10 A. Housed in a compact, IP20-rated enclosure weighing only 0.19 kg (0.42 lbs), this terminal unit simplifies panel building by separating permanent field wiring from active system electronics.

Core Technical Advantages

Separation of Field Wiring and Active Electronics

The passive terminal unit architecture of the TU715F allows plant assembly teams to completely wire, terminate, and test field instrumentation signals before the active S700 electronic I/O processor modules are clicked into place. This operational flow accelerates commissioning and shields sensitive digital components from commissioning-phase wiring faults.

High-Capacity 10 Amp Current Bus

Engineered to handle dense field arrays, the integrated bus rails inside the TU715F support a robust total current throughput of 10 A. This allows efficient power distribution across multiple connected loops, sensors, or actuator circuits directly through the terminal terminal blocks without requiring secondary distribution blocks.

Industrial-Grade Screw Terminal Arrays

The unit features heavy-duty, industrial-grade screw terminals supporting a broad wire size configuration of 0.08 to 2.5 mm² (solid or stranded). The 1/2 wire terminal configuration provides secure clamping force, preventing localized terminal resistance and loose wire connections caused by continuous ambient machine vibration.

Technical Specifications

Installation and Maintenance

DIN Rail Mounting and Base Interlocking

The TU715F is designed for standard 35mm DIN rail mounting inside industrial control enclosures. Snap the unit vertically onto the DIN rail track. When expanding the local remote cluster, slide adjacent terminal units flush against each other to lock the integrated side connectors, creating a reliable lateral communication and power bus backbone.

Field Conductor Termination Procedures

Strip the jacket of the solid or stranded copper wires back according to standard guidelines. Insert the exposed conductor into the designated screw-clamp terminal slot, ensuring no loose strands remain outside the barrel. Tighten the clamping screw to specification to create a high-integrity, gas-tight electrical contact points.

Hot-Swap Electronic Replacement Protocols

Because the TU715F base retains all field wiring on its stationary housing, the active electronic S700 I/O modules can be hot-swapped or replaced without disconnecting a single field wire. Simply release the module's mechanical lock, pull the module forward out of the TU715F base, and insert the replacement card to resume processing operations.

Engineering Advantages

Streamlined Long-Term Facility Maintenance

By keeping field wiring secured to the stationary TU715F terminal unit, plants reduce human error during equipment updates. Maintenance technicians can replace active electronic modules within seconds without risking incorrect field wiring re-connections or loose terminals.

Class 1 Div 2 Hazardous Environment Certification

With official cULus Class 1 Division 2 certification, this terminal unit base is built for safe operation in harsh or volatile environments where explosive vapors may occasionally occur, making it ideal for petrochemical skids, water treatment operations, and oil and gas processing hubs.

Compact High-Density Control Panels

The compact 68mm width provides high channel concentration within a small footprint, allowing system engineers to design smaller distributed marshaling boxes and reduce overall hardware footprints and control room infrastructure costs.

Technical FAQs

Q1: Does the TU715F include any active microprocessor chips or built-in configuration firmware?
A1: No. The TU715F is a completely passive hardware base unit that contains structural copper routing paths, internal backplane jumpers, and mechanical screw terminals. All intelligence, software configurations, and signal processing reside within the electronic S700 I/O modules that plug into it.

Q2: Can I mix solid and stranded conductor profiles on the same TU715F terminal block?
A2: Yes. The high-performance screw-type terminals accommodate both solid and stranded copper wire profiles ranging from 0.08 to 2.5 mm². However, it is a recommended engineering practice to install crimp ferrules on stranded wires to prevent fraying and ensure clean connections.

Q3: What is the benefit of the 10A current rating on a passive base unit?
A3: The 10A current load capacity ensures the internal bus lines can handle the combined power draw of up to 12 active I/O field devices or loop-powered transmitters simultaneously. This robust rating prevents overheating and trace failure under continuous full-load operating conditions.