A New Method for the Detection and Quantification of Residual Volatiles in XLPE Electrical Cable Using Large-Spot Raman Spectroscopy

The residual products of the cross-linking process for high-voltage (HV) and medium-voltage (MV) cable materials are manifold but the two most important byproducts are cumyl alcohol (CA) and acetophenone (AC). Due in part to the presence of these byproducts, cables must be degassed for several days at elevated temperature before the product can be shipped, possibly limiting production throughput. There are few analytical means available to conveniently monitor the quantities of these byproducts during degassing. In this paper, we describe the use of a recently developed technology and enhanced measurement technique that employs large-spot Raman spectroscopy for the quantification of CA and AC. The sampling involves the use of an incident laser spot which can range from 1 to 6 mm in diameter to facilitate the achievement of accurate quantitative results. This approach would allow monitoring of degassing so that an accurate, results-oriented specification could be set for the shipment of HV and MV cable products following production. As such, this methodology has the potential to facilitate better product consistency among manufacturers.