Moku Pahu Navigation Light Panel System

Fail-Safe Electric designed and built a complete PLC-driven navigation light monitoring and control panel for the M/V Moku Pahu, a commercial ocean-going vessel. The system provides centralized bridge control of all navigation, towing, anchor, and safety lights with integrated failure detection and alarm annunciation.

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The panel utilizes a Schneider Electric TM221C40R programmable logic controller with expansion I/O modules to monitor 15 separate lighting circuits through current-sensing inputs. Each circuit features redundant upper and lower fixtures with independent HMI control switches, allowing the crew to select primary or backup lights as operational conditions require. When a commanded light fails to draw current within a 2-second delay window, the system triggers both visual HMI indications and an audible alarm to alert the bridge watch.

Navigation circuits include starboard, port, masthead/range/tow, NUC (Not Under Command) indicators, stern lights, and anchor lights for both the tug and barge. The system also monitors life raft illumination and provides spare circuits for future expansion. Operators can silence active alarms while maintaining visual fault indication until the condition is cleared and reset.

The project scope encompassed PLC programming, panel fabrication, current transformer integration, HMI configuration, and complete documentation including ladder logic printouts and I/O cross-reference tables. The system was delivered fully tested and ready for installation aboard the vessel.