System

{{entity:Industrial Elevator Control System}} ({{hex:D6B77058}}), a SIL 3 group elevator control architecture for industrial buildings. This is the final review session — the system was previously reviewed in session 457, which failed on 55 unlinked SUB requirements, missing SYS-REQ-019 downstream traces, and 8 high-severity lint findings. Intervening QC sessions resolved all blockers. At entry: 223 requirements (14 STK, 16 SYS, 74 SUB, 26 IFC, 11 ARC, 82 VER), 236 trace links, 8 diagrams, 20 baselines, 0 orphans.

Coherence

The six subsystems partition the system cleanly. {{entity:Safety Controller Subsystem}} ({{hex:51B73858}}) owns all SIL 3 safety functions — overspeed, door interlock, fire/seismic response. {{entity:Traction Drive Subsystem}} handles motion control through {{entity:Motor Control Unit}} ({{hex:51F57218}}) and {{entity:Variable Frequency Drive}} ({{hex:D4F53018}}). {{entity:Door Operator Subsystem}} ({{hex:55F77858}}) is architecturally separated from traction, with its own {{entity:Door Control Unit}} ({{hex:50F57A18}}). {{entity:Group Dispatch Controller}} ({{hex:41F77B08}}) is software-only — destination dispatch with traffic-learning. {{entity:Power Distribution Subsystem}} ({{hex:54F51018}}) provides UPS-backed ATS with ARD battery rescue. {{entity:Building Integration Gateway}} ({{hex:50F57A18}}) consolidates BACnet/IP, event logging, and safety command validation.

No functional overlaps detected. The interface set (26 IFC requirements) covers all subsystem boundaries. Architecture decisions (11 ARC) are internally consistent — SIL 3 dual-channel for safety, PMSM gearless drive for traction, EN 81-72/77 compliance for fire and seismic.

flowchart TB
  n0["Industrial Elevator Control System"]
  n1["Traction Drive Subsystem"]
  n2["Safety Controller Subsystem"]
  n3["Door Operator Subsystem"]
  n4["Group Dispatch Controller"]
  n5["Power Distribution Subsystem"]
  n6["Building Integration Gateway"]
  n7["Building Management System"]
  n8["Fire Alarm Panel"]
  n2 -->|Brake permit, STO| n1
  n2 -->|Interlock status| n3
  n4 -->|Target floor| n1
  n4 -->|Door commands| n3
  n5 -->|3-phase power| n1
  n6 -->|BMS commands| n4
  n6 -->|Fire relay| n2
  n7 -->|BACnet/IP| n6
  n8 -->|Hardwired relay| n6

Completeness

Trace chain coverage is 100% at every level: all 14 STK requirements trace to SYS (21 links), all 16 SYS trace to SUB/IFC/ARC (100 links), and all 100 SUB+IFC requirements trace to VER (105 links). One gap found: {{sub:SUB-REQ-076}} (cabinet IP54 enclosure) lacked a VER trace — closed this session by linking to {{sub:VER-REQ-083}} (enclosure inspection). ConOps scenario validation from session 455: morning rush (covered), single car failure (gap closed), power failure with passengers (partial — ARD travel-time for mobility-impaired not explicitly tested), fire alarm recall (Phase I covered, Phase II added), seismic event (covered), maintenance mode (VER added).

Acceptance Assessment

Procurement authority: Yes — requirements are specific, measurable, and include rationale. EARS patterns used throughout. SIL allocation is explicit (SIL 3 for safety controller, SIL 2 for fire/seismic interfaces). Performance values are derived from standards (EN 81-20, IEC 61508, EN 12015/12016).

Test organisation: Yes — 82 VER requirements specify test setups, stimuli, and acceptance criteria. Proof test interval requirement ({{sub:SUB-REQ-075}}) was added after cross-domain analog with nuclear reactor protection system flagged its absence.

Safety authority: The safety argument is coherent. Hazard-driven SIL allocation traces through: H-001 (uncontrolled car movement) → SYS-REQ-003/004 → SUB-REQ-001/002/003 → VER-REQ-005/027/028. IEC 61508 proof test intervals specified. Dual-channel architecture documented in ARC-REQ-001.

Per-Subsystem Summary

Subsystem	SUB	IFC	ARC	VER	Diagram
Safety Controller	30	6	1	20	Yes
Traction Drive	15	4	2	15	Yes
Door Operator	15	6	1	10	Yes
Group Dispatch	8	4	2	8	Yes
Power Distribution	16	3	1	10	Yes
Building Integration	16	3	2	10	Yes

Safety Controller has the deepest decomposition (30 SUB reqs) — appropriate for SIL 3. Group Dispatch has the fewest (8) — appropriate for a software-only subsystem.

Cross-Domain Insights

Analog	Score	Gap Surfaced
Nuclear Safety Interlock ({{hex:50F77859}})	67%	Proof test interval for SIL 3 PFDavg
Variable Frequency Drive ↔ Safety Output Actuator	77%	Redundancy requirements for system-essential components

Corrections

One trace link added: {{sub:SUB-REQ-076}} → {{sub:VER-REQ-083}} (cabinet IP54 inspection). Stale REVIEW_NOTES fact from session 457 deleted. CURRENT_SE_PROJECT/SYSTEM/NAMESPACE facts cleaned up (were not cleared after previous completion marking).

Efficiency

System completed across approximately 22 sessions (436–458), spanning 2026-03-21 to 2026-03-22. 21 baselines created. One review failure (session 457) triggered additional QC work that brought VER coverage from 59% to 100%. No wasted sessions — the rework cycle was productive.

Residual

50 medium-severity lint findings remain, all ontological mismatches ({{trait:Synthetic}} without manufacturing requirements, {{trait:System-Essential}} without redundancy requirements, {{trait:Physical Medium}} without material requirements). These are appropriate at the system specification level — manufacturing, material selection, and redundancy architecture are detailed design concerns. The specification delegates these to the subsystem design phase.

Coverage gaps for specific concept phrases (e.g., “designated landing”, “BACnet B-ASC device profile”) are flagged by the linter but are addressed by the substance of traced requirements even when the exact phrase is not repeated verbatim at lower levels.

Verdict

PASS. The {{entity:Industrial Elevator Control System}} specification is coherent, complete, and proportionate. 223 requirements with 100% trace coverage, 82 verification procedures, and a coherent SIL 3 safety argument. Baseline COMPLETE-2026-03-22 created. This is the 20th system completed in the autonomous loop.