PLC information issued
Programmable Logic Controllers (PLCs) are widely used in a variety of small and large pieces of equipment on marine construction vessels, including cranes, winches, handling systems, dive systems and power management systems.
The International Marine Contractors Association (IMCA) has issued a PLC information note to help ensure that operation and failure modes are understood, and highlighting the importance of carrying out an FMEA (failure modes and effects analysis) and testing the components and complete systems.
When a PLC controlled piece of equipment is in use and a main power failure occurs, the equipment should revert to a fail-safe position, for example, brakes will be applied, valves may close or open and pressure may be ‘locked in’ or prevent movement.
The information note (IMCA M 15/12) highlights steps to be taken if PLC controlled equipment is new, or if an existing PLC is replaced with a new CPU, or the software programming of a PLC CPU has been modified or accessed in any way. It also provides useful references to PLC controlled equipment.
Related Articles
MARINE CONSTRUCTION
POWER & PROPULSION
ENVIRONMENT