2010 1 RESOLVING CP DESIGN RESTRICTIONS AT AN AUSTRALIAN WHARF: A NOVEL MARINE IMPRESSED CURRENT CP SYSTEM Rajko Vukcevic and John Furstenberg SMPS (Australia) Pty Ltd Unit 9, 556 North Road Ormond 3204, Australia Ian Godson Ian Godson & Associates Pty Ltd Unit 16, 96 Camberwell Road Hawthorn East 3123, Australia ABSTRACT This paper presents resolutions to cathodic protection (CP) design restrictions at an Australian 1km long steel-pile container wharf, requiring a 3,500A impressed current CP (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 transformer-rectifier units (TRUs) and low-voltage/high-current DC distribution, these restrictions would result in cable cross- sections of up to 120mm 2 per anode leg. Instead, a novel DC power distribution system was utilized, consisting of parallel channels of high-voltage/low-current Power Supply units (PSUs) 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÷2.5mm 2 twin-core cables, distributing 2A@300V dc max towards each anode, where Current Multipliers transform it into 45A@9V dc 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%. Keywords: current multiplier, energy efficiency, impressed current cathodic protection, marine corrosion, power distribution system INTRODUCTION Of all the impressed current CP (ICCP) systems in the corrosion protection industry, sea-water systems supply by far the largest DC currents to steel structures – from hundreds to several thousands of Amps per structure. ©2010 by NACE International. Requests for permission to publish this manuscript in any form, in part or in whole, must be in writing to NACE International, Publications Division, 1440 South Creek Drive, Houston, Texas 77084. The material presented and the views expressed in this paper are solely those of the author(s) and are not necessarily endorsed by the Association. 1 Paper No. 10031