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The AC Close Interval Survey and Other Common AC Measurement Errors

The measurement of induced AC voltages along a pipeline is a primary indicator of electrical safety hazards and AC corrosion risks under operating powerlines. This paper addresses several fallacies, misconceptions and common errors related to the measurement of these AC induced voltages.

 

Product Number: 51317--9455-SG
ISBN: 9455 2017 CP
Author: Wolfgang Fieltsch
Publication Date: 2017
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$20.00
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With an increase in the use of shared corridors between powerlines and pipelines AC interference risks to pipelines have become a more prominent concern. AC interference can result in pipeline integrity risks such as AC corrosion coating damage and arcing and safety risks to pipeline personnel and the public due to elevated touch or step potentials.The measurement of induced AC voltages along the pipeline is the primary indicator of the safety and AC corrosion risk under steady state operation of influencing powerlines. This paper addresses several fallacies misconceptions and common errors related to the measurement of these AC induced voltages.Many operators monitor AC voltage levels at test posts on an annual basis as part of their cathodic protection survey. However the test stations are often not located at or close to the AC voltage peaks on the pipeline. In an attempt to determine the AC voltage profile along the pipeline some operators and consultants perform AC close interval surveys. This technique will be shown to be invalid via technical principles software modeling and an assessment of close interval survey data.Another phenomenon that is often overlooked is the variability of the measured AC voltage which will fluctuate with the powerline loading throughout the day from day to day seasonally and annually. A one-time annual measurement at test posts is not a good indicator of the AC interference risk on the pipeline.Finally induced AC voltages should be measured with respect to remote earth. When AC measurements are taken in proximity to grounding or other AC mitigation facilities the AC current discharging to the ground creates a potential gradient in the soil which will result in a much lower measured AC voltage.Keywords:AC Interference AC Close Interval Survey Close Interval Survey AC Voltage Measurement Monitoring AC Survey High Voltage AC (HVAC) Transmission Powerlines Pipelines.

Keywords: AC Interference, AC Mitigation, AC Close Interval Survey, Close Interval Survey (CIS), Monitoring, AC Voltage Measurement, AC Survey, High Voltage AC (HVAC), Transmission Powerlines, Pipelines

With an increase in the use of shared corridors between powerlines and pipelines AC interference risks to pipelines have become a more prominent concern. AC interference can result in pipeline integrity risks such as AC corrosion coating damage and arcing and safety risks to pipeline personnel and the public due to elevated touch or step potentials.The measurement of induced AC voltages along the pipeline is the primary indicator of the safety and AC corrosion risk under steady state operation of influencing powerlines. This paper addresses several fallacies misconceptions and common errors related to the measurement of these AC induced voltages.Many operators monitor AC voltage levels at test posts on an annual basis as part of their cathodic protection survey. However the test stations are often not located at or close to the AC voltage peaks on the pipeline. In an attempt to determine the AC voltage profile along the pipeline some operators and consultants perform AC close interval surveys. This technique will be shown to be invalid via technical principles software modeling and an assessment of close interval survey data.Another phenomenon that is often overlooked is the variability of the measured AC voltage which will fluctuate with the powerline loading throughout the day from day to day seasonally and annually. A one-time annual measurement at test posts is not a good indicator of the AC interference risk on the pipeline.Finally induced AC voltages should be measured with respect to remote earth. When AC measurements are taken in proximity to grounding or other AC mitigation facilities the AC current discharging to the ground creates a potential gradient in the soil which will result in a much lower measured AC voltage.Keywords:AC Interference AC Close Interval Survey Close Interval Survey AC Voltage Measurement Monitoring AC Survey High Voltage AC (HVAC) Transmission Powerlines Pipelines.

Keywords: AC Interference, AC Mitigation, AC Close Interval Survey, Close Interval Survey (CIS), Monitoring, AC Voltage Measurement, AC Survey, High Voltage AC (HVAC), Transmission Powerlines, Pipelines

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51316-7393-AC Interference Risk Ranking: Case Study

Product Number: 51316-7393-SG
ISBN: 7393 2016 CP
Author: Wolfgang Fieltsch
Publication Date: 2016
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