The Effect of Inductive Loading on Cathodic Protection Interruption Surveys

Key words: interruption, inductive loading, survey, contactor, relay, solid state, interrupter failure INTRODUCTION In cathodic protection surveying of impressed current systems, it is necessary to interrupt, or stop, the flow of current from a rectifier, or series of rectifiers, in order to measure...

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Bibliographic Details
Published inNACE International Corrosion Conference Proceedings pp. 1 - 8
Main Authors Dockery, Michael M, Gibson, Stephen B
Format Conference Proceeding
LanguageEnglish
Published Houston NACE International 01.07.2020
Subjects
Cathodic protection
Circuit protection
Contactors
Corrosion prevention
Electric currents
Electrode polarization
Failure modes
Inductance
Interrupters
Interruption
Mercury (metal)
Passive components
Rectifiers
Relay
Soil resistance
Solid state devices
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Summary:Key words: interruption, inductive loading, survey, contactor, relay, solid state, interrupter failure INTRODUCTION In cathodic protection surveying of impressed current systems, it is necessary to interrupt, or stop, the flow of current from a rectifier, or series of rectifiers, in order to measure the polarization of the structure. Traditionally a mechanical contactor or a mercury relay is used for this. Since mechanical contactors can become degraded by dirt, dust, or corrosion, and mercury is a harmful substance avoided often by rectifier owners, there has been an increase in demand for a solid state means of interruption. Solid state devices, however, have their own failure modes that are not always fully understood in cathodic protection circuits. To demonstrate this, an artificial cathodic protection circuit was set up with a tap adjust rectifier, a commonly available current interrupter, and passive components to represent the soil resistance and wire inductance.