RESOLVING CP DESIGN RESTRICTIONS AT AN AUSTRALIAN WHARF: A NOVEL MARINE IMPRESSED CURRENT CP SYSTEM

This paper presents resolutions to CP design restrictions at an Australian 1km long steel-pile container wharf requiring a 3,500A ICCP system.  Rectifier locations were confined to ends of the wharf, while all cablework from rectifiers to anodes and piles had to be mounted underneath the dock.  In a traditionally designed ICCP system using TRUs and low-voltage/high-current DC distribution, these restrictions would result in cable cross-sections of up to 120mm² per anode leg.  Instead, a novel DC power distribution system was utilized, consisting of parallel channels of high-voltage/low-current Power Supply units feeding adjustable constant current into Current Multiplier DC/DC converters located close to anodes.  Thus, power cables leading from PSUs could all be 1.0÷2.5mm² twin-core cables, distributing 2A@300Vdc max towards each anode, where Current Multipliers transform it into 50A@10Vdc max.  A single-anode prototype was developed as a proof-of-concept trial system, and then a full 77-anode ICCP system was constructed for the complete wharf corrosion protection.  Major parameter values of the installed distribution cable network were considerably reduced – the average cable cross-section size by a factor of 30, the total cable weight by 12, and the total cable material and installation costs by 15÷20.  Total system power consumption from AC-mains was cut down by 55%.