Description:
The ABB NAOM01 (Bailey Part No. 6631966D1) is an Analog Output Module designed for ABB Bailey INFI 90, Network 90, and Symphony / Symphony Plus Harmony DCS systems. It converts digital control signals from the DCS controller into standard industrial analog signals — typically 4–20 mA DC or 0–10 V DC — to drive field final control elements such as control valves, variable frequency drive speed references, dampers, and analog recorders, with high accuracy and electrical isolation between channels.
Application Scenarios:
A 600 MW coal-fired power plant’s boiler combustion control system used an ABB INFI 90 DCS rack to modulate the forced draft (FD) and induced draft (ID) fan inlet guide vanes via 4–20 mA analog outputs. During a routine alarm review, the operators noticed that one FD fan’s positioner was not tracking the setpoint despite correct digital logic in the controller. Loop checks revealed the corresponding ABB NAOM01 AO channel was outputting a fixed 0 mA with the module’s green COM LED blinking normally — a classic symptom of an internally degraded output amplifier stage. The I&C technician powered down the rack (NAOM01 is not hot-swappable on most legacy racks), removed the NAOM01, inserted a verified replacement, restored power, and re-ramped the loop — the 4–20 mA signal tracked perfectly and the FD fan vane responded. No database changes or I/O re-mapping were required. This real-world scenario highlights the NAOM01‘s role as the critical D/A translation point in process control loops, and why keeping a tested spare in the storeroom avoids extended process upsets.
Parameter:
| Main Parameters | Value/Description |
|---|---|
| Product Model | NAOM01 (Bailey P/N: 6631966D1) |
| Manufacturer | ABB (Bailey Controls / Process Automation) |
| Product Category | Analog Output Module (AO) for DCS I/O Rack |
| Compatible System | ABB INFI 90 Open, Network 90, Symphony Plus Harmony (MFP / ICP Rack) |
| Output Channels | 4 or 8 independent channels (model variant / firmware dependent; commonly 4-ch per MIL-spec, 8-ch per later revision) |
| Output Signal Types | 4–20 mA DC, 0–20 mA DC (current mode), 0–10 V DC, ±10 V DC (voltage mode — per configuration) |
| Output Accuracy | ±0.1 % of Full Scale (FS) at 25 °C |
| Resolution | 12-bit typical / 16-bit on later revisions |
| Load Capability | ≤ 500–750 Ω (current output); ≥ 1 kΩ (voltage output) |
| Isolation | ≥ 500 V AC channel-to-channel & channel-to-system (galvanic) |
| Module Power | +5 V DC & +24 V DC from rack backplane (no external PSU required) |
| Response Time | < 10 ms (full-scale step change) |
| Status Indication | Module Power (PWR), Communication Active (COM), individual channel activity / fault via system diagnostics |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -40 °C to +85 °C |
| Humidity | 5 %–95 % RH, non-condensing |
| Mounting Method | Standard DCS rack slot (card-guide + backplane edge connector); secured by front panel screw / ejector |
| Protection Class | IP20 (for enclosed cabinet installation) |
| Dimensions (approx.) | 290 × 130 × 40 mm (L × W × H) |
| Weight (approx.) | 0.40 – 0.50 kg |
Technical Principles and Innovative Values:
- Innovation Point 1 — High-Resolution D/A Conversion with Per-Channel Software Configuration. The ABB NAOM01 uses precision digital-to-analog converters to transform the controller’s digital output word into a proportional analog current or voltage. Each channel’s signal type (4–20 mA vs 0–10 V) and range scaling are software-selectable via the INFI 90 / Symphony engineering tool (e.g., SysCon / Control Builder), eliminating the need for DIP switches or jumper changes — a flexibility that simplifies spare-part standardization across different loop types.
- Innovation Point 2 — Galvanic Channel Isolation & Transient Protection. Every output channel on the NAOM01 is galvanically isolated from the system backplane and from other channels (≥ 500 V AC test). This prevents ground-loop errors in multi-loop applications and protects the sensitive DCS logic from field-side transients such as inductive kickback from solenoid valves or VFD common-mode noise.
- Innovation Point 3 — Built-In Output Diagnostics & Fault Reporting. The module continuously monitors each channel for open-circuit (broken wire in current loop), over-range, and compliance voltage drop below minimum. Fault conditions are reported to the controller’s diagnostic database and can trigger operator alarms — allowing maintenance to identify a failed loop transmitter or wiring break before it impacts process control, rather than discovering it during a trip.
