Advanced Inspection Techniques for Monitoring Cable Aging Module 3 Dr. John H. Bickel Evergreen Safety & Reliability Technologies, LLC

Two Types of Inspection Techniques for Monitoring Cable Aging In-situ or Non-destructive Methods In-situ or Non-destructive Methods Methods requiring removal of cable Methods requiring removal of cable

Time Delay Reflectrometry TDR works similar to RADAR TDR works similar to RADAR TDR pulse is injected to length of cable TDR pulse is injected to length of cable Reflections generated at points of changes in Impedance Reflections generated at points of changes in Impedance TDR historically used for transmission system cable to determine moisture buildup in cable TDR historically used for transmission system cable to determine moisture buildup in cable TDR can identify problems with local materials breakdown, connector corrosion TDR can identify problems with local materials breakdown, connector corrosion

Time Delay Reflectrometry

TDR Benefits TDR successfully used in many types of cables and cable geometries. TDR successfully used in many types of cables and cable geometries. TDR has found: cracking in insulation, corrosion, water intrusion, poor electrical connections TDR has found: cracking in insulation, corrosion, water intrusion, poor electrical connections TDR can identify location of major change in Impedence – which requires further investigation. TDR can identify location of major change in Impedence – which requires further investigation.

Microscopy Techniques Scanning Acoustic Microscope Scanning Acoustic Microscope Scanning Electron Microscope Scanning Electron Microscope Both require representative samples of cable materials Both require representative samples of cable materials Primarily used to determine average insulation void content, void size Primarily used to determine average insulation void content, void size

Scanning Acoustic Microscopy

Scanning Electron Microscopy

Microscopy Microscopy has been very useful in identifying mechanisms for aging related degradation. Microscopy has been very useful in identifying mechanisms for aging related degradation. Microscopy identified the role of gas pocket buildup in insulation layer as mechanism of degradation. Microscopy identified the role of gas pocket buildup in insulation layer as mechanism of degradation. Not easily used for determination of residual life. Not easily used for determination of residual life.