ISO 13374 — Overview
Introduction to the ISO 13374 condition monitoring standard and how Rela AI implements its 6 levels.
What is ISO 13374
ISO 13374 is the international standard for condition monitoring and diagnostics of machines. It defines a six-level data processing architecture that transforms raw sensor data into actionable maintenance recommendations.
Rela AI implements all six levels of the standard, allowing organizations to progressively evolve from simple data collection to automatic generation of predictive recommendations.
The 6 levels
L1 — Data Acquisition
Collection of raw data from event sources: sensors, PLCs, SCADA systems, IoT devices. Data is normalized and stored with its original timestamp.
Supported protocols (6):
| Protocol | Typical use |
|---|---|
| HTTP/REST | Web integrations, webhooks, third-party APIs |
| MQTT | IoT sensors, lightweight pub/sub communication |
| OPC UA | SCADA systems, industrial PLCs |
| Modbus TCP | Legacy industrial equipment, meters |
| WebSocket | Real-time streaming, dashboards |
| CSV/Batch | Bulk import of historical data |
Implementation in Rela AI:
- Event sources configurable per protocol.
- Real-time ingestion with schema validation.
- Storage in MongoDB with temporal indexes.
L2 — Data Manipulation
Statistical processing of raw data to extract trends, averages, and detect anomalies. Converts point data into continuous information.
Implementation in Rela AI:
- Rolling statistics (min, max, avg, stddev).
- Linear regression and moving averages (SMA/EMA).
- Anomaly detection via z-score and bands.
L3 — State Detection
Compares current data against learned baselines to determine equipment condition state. Identifies operating modes and deviations.
Implementation in Rela AI:
- Automatic baseline learning.
- Operating modes: normal, startup, shutdown, standby.
- Condition evaluation: good, acceptable, unsatisfactory, unacceptable.
L4 — Health Assessment
Combines multiple indicators into a single health index (AHI) that summarizes the overall asset condition with a grade from A to F.
Implementation in Rela AI:
- Asset Health Index (AHI) from 0 to 100.
- Four sub-indices with configurable weights.
- Deterministic recommendations per grade.
L5 — Prognostics
Estimates the remaining useful life of equipment and predicts when maintenance will be required based on degradation trends.
Implementation in Rela AI:
- Remaining Useful Life (RUL) estimation.
- Degradation rate (AHI points/day).
- Condition-based maintenance (CBM) triggers.
L6 — Advisory
Generates specific action recommendations using artificial intelligence, considering the full asset context.
Implementation in Rela AI:
- Recommendations generated by Gemini.
- Managed lifecycle (open, acknowledged, resolved).
- Automatic creation of urgent tasks.
Summary table
| Level | Name | Rela AI Service | Input | Output |
|---|---|---|---|---|
| L1 | Data Acquisition | Event Sources | Raw data | Normalized events |
| L2 | Data Manipulation | Trend Analysis | Events | Statistics and trends |
| L3 | State Detection | Baselines | Trends | Condition state |
| L4 | Health Assessment | Asset Health | Condition | AHI and grade |
| L5 | Prognostics | Prognostics | Historical AHI | RUL and risk |
| L6 | Advisory | Advisories | All of the above | Recommendations |
Each level can function independently, but maximum value is achieved when all levels are active and feeding into each other.
Progressive activation
You do not need to implement all six levels at once. The recommended path is:
- Phase 1 — Configure event sources (L1) and trend analysis (L2).
- Phase 2 — Learn baselines (L3) and activate health assessment (L4).
- Phase 3 — Enable prognostics (L5) and AI recommendations (L6).
Higher levels (L5, L6) require sufficient historical data to generate reliable predictions. At least 30 days of data is recommended before activating prognostics.
Predictive Maturity Levels
Each asset automatically progresses through 4 levels as it accumulates data:
| Level | Name | Requirements | Capabilities |
|---|---|---|---|
| 0 | Monitoring | No data | Basic alerts |
| 1 | Health Tracking | 10+ snapshots | AHI active, visible trends |
| 2 | Prediction | 30+ snapshots + 1 failure | Reliable RUL, recommendations |
| 3 | Optimized | 30+ snapshots + 3 failures + confidence > 70% | Full automation |
Progression is automatic — the system evaluates each level's requirements and promotes the asset when they're met. No manual configuration needed.
Predictive KPIs
Value metrics for predictive maintenance including anomaly-to-WO time, false positive rate, percentage of auto-created WOs, unplanned downtime, and RUL accuracy.
Baselines and Condition State
Baselines record how equipment behaves when it is healthy. The system compares each new measurement against that reference to automatically detect when something changes.