Laser characterization of cable insulation: Final report
An instrument capable of detecting voids and contaminants in the insulation of extruded polyethylene has been previously developed. This instrument utilizes a far-infrared laser (FIRL) system operating at 119 microns. If a void or contaminant is present, the FIRL beam is scattered. This scattered beam is then detected and signals the presence of an imperfection in the cable. The current investigation was undertaken to explore the limitations of the FIRL over a range of laser wavelengths and on commercially available and derivations of commercially available conductor shield materials. Experimental results showed that all commercially available semiconductor materials are opaque to FIRL transmission at wavelengths up to 500 microns. Some experimental materials based on present materials technology showed transmission up to 14 percent at wavelengths of 447 microns. Measurements showed that void detection decreases as FIRL attenuation and wavelength increase. Cables of various insulation shield materials of 625 microns thickness were modeled. These experiments showed that with the present FIRL inspection instrument, it is not possible to detect voids and contaminants in triple-extruded insulation with commercially available semiconductor materials. If (1) the laser wavelength is increased to 447 microns, (2) the laser power is increased to 1 W-cm/sup /minus/2/, and (3) the experimental insulation shield material is developed to provide a 14 percent transmission at 447 microns, it would then be possible to detect voids and contaminants in triple extruded cable insulation provided that the size of these defects is 250 microns or greater. 28 figs., 8 tabs.
- Research Organization:
- United Technologies Research Center, East Hartford, CT (USA)
- OSTI ID:
- 5019973
- Report Number(s):
- EPRI-EL-5669; ON: TI88010999
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ELECTRIC CABLES
ELECTRICAL INSULATION
INSPECTION
ATTENUATION
CARBON DIOXIDE LASERS
DEFECTS
DETECTION
FAR INFRARED RADIATION
VOIDS
CABLES
CONDUCTOR DEVICES
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
EQUIPMENT
GAS LASERS
INFRARED RADIATION
LASERS
RADIATIONS
420500* - Engineering- Materials Testing