
Application Scenarios:A fossil-fuel power plant running an ABB Bailey Infi 90 DCS discovered that several analog input modules in Rack #3 stopped updating values, while the Multifunction Processor (MFP) and other racks remained healthy. After ruling out module and termination block faults, technicians identified a cracked trace and oxidized edge connector on the aging I/O distribution board. They replaced it with the ABB 663636IAI. Because the 663636IAI is a form-fit, function-identical replacement for the original MCS rack distribution PCB, the rack was brought back online in under 30 minutes—restoring full I/O communication without rewiring field terminations or reconfiguring the DCS database. The 663636IAI directly solves the pain point of unexplained rack-wide I/O loss due to backplane degradation, preserving legacy system uptime at a fraction of the cost of a full DCS upgrade.h2
Parameter:
| Main Parameters | Value/Description |
|---|---|
| Product Model | 663636IAI |
| Manufacturer | ABB (Bailey Controls / Elsag Bailey heritage) |
| Product Category | I/O Distribution Board / Backplane Signal Bus Board |
| Compatible Series | Bailey MCS (Modular Control System), Infi 90, Net 90, MCS-51 / MCS-91 Racks |
| Mounting Method | Internal MCS rack mounting — secured by screws / guide slots to rack backplane |
| Backplane Interface | Edge-card connector — mates with MCS rack backplane bus |
| Signal Function | Distributes I/O communication bus, module addressing, and field signal terminations |
| Typical Dimensions | 464 × 22 × 198 mm (approx. 46.4 × 2.2 × 19.8 cm) |
| Weight | Approx. 0.60 – 0.70 kg |
| Operating Temp. | -20 °C to +60 °C |
| Storage Temp. | -40 °C to +85 °C |
| Environmental Rating | IP20 (installed inside enclosed control cabinet / rack) |
| ESD Sensitivity | Yes — handle with ESD wrist strap; do NOT hot-swap |
h2 Technical Principles and Innovative Values:
- Backplane Signal Integrity & Low-Crosstalk Layout: The 663636IAI uses a precision-etched multilayer PCB layout to maintain signal integrity across all I/O module slots. Controlled impedance traces and proper ground referencing minimize crosstalk and ensure reliable high-speed communication between the MFP/controller and each I/O module seated in the rack.
- Drop-In Legacy System Sustainment: Unlike generic distribution boards, the ABB 663636IAI is engineered to the exact mechanical and electrical tolerances of the original Bailey MCS rack specification—including slot spacing, connector pinout, and retention hardware—making it a true “remove-and-replace” spare with zero re-engineering required for existing Infi 90 / Net 90 installations.
- Field-Wiring Preservation: Because the 663636IAI interfaces with the rack backplane rather than directly to field cables (field wires terminate on separate TB/TA termination blocks), replacing it never disturbs field wiring. This dramatically reduces risk during emergency repairs and shortens mean time to repair (MTTR) compared to replacing an entire I/O rack assembly.
h2 Application Cases and Industry Value:Case 1 – Oil Refinery Bailey Infi 90 Rack Refurbishment:An Asian refinery operating four Bailey Infi 90 process units scheduled a phased refurbishment of aging DCS hardware. As part of the program, all MCS rack I/O distribution boards—including the ABB 663636IAI—were proactively replaced during a planned turnaround. Post-replacement, all 16 I/O modules per rack were recognized by the MFP without any configuration changes. The plant reported zero I/O communication alarms across the units post-startup, extending the viable service life of the legacy DCS by an estimated 8–10 years.







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