Cathodic Protection is a unique technique to control corrosion of metal by making the subject metal as the cathode of an electrochemical cell. Here the metal to be protected, referred to as cathode, is electrically connected to an easily corroded metal, referred to as sacrificial metal or galvanic anode. The chemical reaction taking place in an electrochemical cell causes the cathode to be protected and anode to disintegrate. For larger structures and where electrolytes have high resistivity, the potential difference between cathode and galvanic anode is not enough to generate sufficient current required for the protection of cathode. In such cases impressed current cathodic protection (ICCP) systems are used instead of galvanic anode systems. ICCP systems makes use of an external steady state direct current (DC) power source or a transformer rectifier (TR) to provide the required cathodic protection current. ICCP systems with steady state DC is used since 1950’s. This paper presents the methodology, observations and analysis of using pulse width modulated (PWM) DC power source rather than a steady state DC power source on a buried pipeline sample. An experimental setup is made to study corrosion rate, anode life, interference mitigation, etc., when the pipeline is subjected to both steady state and pulsed DC output.
Keywords: Galvanic anodes, impressed current cathodic protection system (ICCP), alternating current (AC), direct current (DC), Mild steel, pipe to soil potential (PSP), backfill, pulse width modulation (PWM), power consumption.