Evaluation of water contents whithin insulating papers used for the construction of accessories on of cables

A methodology for the qualitative evaluation of water content within insulating papers used for the construction of accessories (joints and terminations) on OF (Oil Filled) cables is described. The determination of moisture content within insulating paper is an expensive process regarding the equipment and time involved in the process. It is necessary a clean and environment controlled room, in addition to high cost equipment, in order to achieve that process by means of the conventional Karl Fischer method. It is evident that the construction of joints and terminations on underground cables is almost always performed in uncontrolled environments: dirt, dust, temperature and moisture at the working place are factors which affect the condition of the components used for accessories of OF cables. For that reason, it becomes of great importance to maintain under proper control the condition of those mentioned components, in particular the insulating papers, in order to fulfill the suitable construction of joints and terminations. A methodology for the evaluation of moisture content of insulating papers by immersion into oil and/or paraffin baths at different temperatures is presented, that allows the evaluation of the degree of water contents by observing the amount of bubbles released by the paper into each bath. Traceability with the conventional Karl Fischer method is made from the results of the experience. Using this methodology a fast, cheap and efficient evaluation of moisture content within insulating papers can be made, even during accessories construction in field. Therefore, it is not necessary to use other methods that involve time and expensive equipment, as Karl Fischer's.