Crosslinking of XLPE

he undergrounding of energy transmission cables is widely recognized as a good means to provide reliable supplies of power at a low total cost [1], [2]. As utilities increasingly acknowledge this and install many more high voltage (HV) and extra high voltage (EHV) cables, they will face a major challenge: namely, sourcing the increased amount of high quality power cable with the cable manufacturing infrastructure that exists today. Analysis [3] shows that it is practically possible to reduce the effect of all of today’s constraints to productivity and boost output. At the highest cable voltages, the output and the response time are often determined by the byproduct removal (degassing) procedures. Ensuring that the most appropriate procedures are used enables manufacturers to deliver the amounts of cable needed, without recourse to extra capital investment. Yet safe and productive changes require that the degassing problem and its potential solutions be fully understood. This article focuses on a range of elements critical to this process; from the fundamental chemistry, through computational and measurement techniques to the solutions that are in use today. However, before commencing the discussion, it is useful to be clear on terminology. The process whereby the byproducts of the crosslinking reaction are removed is almost universally termed degassing. Although there is no doubt that gaseous byproducts (primarily methane) are removed during this procedure, this is not the only effect. Within the process all byproducts are redistributed and the solid/waxy byproducts (acetophenone and cumyl alcohol) are reduced in level. Therefore, when the term degassing is used in this paper, we use it to refer to the reduction and redistribution of all crosslinking byproducts, whether they are gaseous or solid.