Description:
The ABB 3BHB002916R0101, also identified as the UFC721AE (UFC721AE01), is an Analog Input Scaling / Termination & Scaling Unit (TSU) card designed for ABB INFI 90 and Symphony Plus Harmony DCS I/O racks. It sits between the field wiring terminals and the Harmony Analog Input Module (AIM — e.g. AI615/AI625), providing signal conditioning (current-to-voltage conversion for 4–20 mA loops, RTD linearization, thermocouple cold-junction compensation), range scaling via DIP switches or jumpers, and electrical isolation — ensuring the AIM receives a clean, accurately scaled low-level voltage proportional to the measured process variable.
Application Scenarios:
A combined-cycle power plant’s #2 HRSG (Heat Recovery Steam Generator) section was seeing sporadic “Analog Input Out-of-Range” alarms on three of its drum-level RTD inputs connected through an older Harmony I/O rack. Verification with a precision calibrator showed the sensors and cabling were good, but the signals at the AIM terminals were noisy and slightly offset — classic symptoms of a degrading signal-conditioning / scaling card. The I&C technician powered down the rack, removed the ABB 3BHB002916R0101 (UFC721AE01) from its slot in the termination unit, and replaced it with a verified spare of identical revision. After re-terminating the field wires (the UFC721AE often mounts in a dedicated termination panel adjacent to or as part of the I/O card cage), power was restored — the drum-level readings stabilized within specification and the alarms cleared. No changes to the controller database or AIM configuration were needed because scaling is set by the onboard DIP switches matching the original card. This case demonstrates the 3BHB002916R0101‘s function as the “analog front-end” that conditions real-world sensor signals for the DCS — and why a correctly jumpered spare is essential for rapid restoration of accurate process measurement.
Parameter:
| Main Parameters | Value/Description |
|---|---|
| Product Model | 3BHB002916R0101 (UFC721AE / UFC721AE01 — Analog Scaling / TSU Card) |
| Manufacturer | ABB |
| Product Category | Analog Input Scaling / Termination & Signal Conditioning Card (Harmony INFI 90 / Symphony Plus) |
| Compatible System | ABB INFI 90 Open / Symphony Plus Harmony I/O Racks (used with AI615, AI625, AI635 Analog Input Modules) |
| Number of Channels | Typically 8 independent analog input channels (matches 8-channel AIM) |
| Supported Input Types | 4–20 mA (active / passive loop), 0–10 V, 0–5 V, RTD (Pt100, Cu50 etc.), Thermocouple (Type J/K/T/E per version) |
| Signal Conversion | 4–20 mA → 1–5 V (precision 250Ω shunt std.), RTD → linearized mV, TC → compensated μV + CJC |
| Scaling Method | Onboard DIP switches / jumper blocks per channel group (selects range, sensor type, burnout direction) |
| Isolation | ≥ 1500 V AC channel-to-system / channel-group isolation (depends on revision) |
| Cold-Junction Compensation | Onboard sensor (for TC inputs) referenced to card temperature |
| Field Wiring | Screw terminals for pair/triple field wires + shield drain (some versions on separate termination block, not on PWA itself) |
| Status Indication | Power LED (some revisions); channel activity inferred via AIM diagnostics |
| Operating Temperature | -20 °C to +60 °C |
| Storage Temperature | -40 °C to +85 °C |
| Mounting Method | Rack slot or dedicated termination unit guide; secured by screw / latch |
| Protection Class | IP20 (installed inside enclosed I/O cabinet) |
| Dimensions (approx.) | 185 × 105 × 20 mm (L × W × H, PWA only; verify against your termination assembly) |
| Weight (approx.) | 0.18 – 0.30 kg |
Technical Principles and Innovative Values:
- Innovation Point 1 — Per-Channel Configurable Signal Conditioning Without Software. The ABB 3BHB002916R0101 uses DIP-switch / jumper blocks to select input type (mA/V/RTD/TC) and range per channel group, converting the field signal to the 0–10 V or 1–5 V span expected by the Harmony AIM. This hardware-based configuration means the scaling card works with any compatible AIM and controller — no engineering downloads or HMI changes are required when replacing the board, provided jumpers match the original setup.
- Innovation Point 2 — Integrated RTD Linearization & Thermocouple Cold-Junction Compensation. For temperature inputs, the UFC721AE incorporates precision current sources for 3-wire RTD excitation and an onboard temperature sensor for TC cold-junction compensation, referenced to the card’s local temperature. This offloads linearization from the AIM firmware and yields ±0.1% typical accuracy across industrial temperature spans — critical for boiler / turbine metal-temperature monitoring.
- Innovation Point 3 — Galvanic Isolation & Transient Protection on Every Channel. Each analog input channel (or channel group) is galvanically isolated from the system side and from other groups, with built-in surge arrestors on the field terminals. This prevents ground loops, rejects common-mode noise on long sensor runs (typical in power plants), and protects the expensive AIM electronics from lightning-induced transients or accidental 120 V AC miswire.
