In this paper of the month, an advanced concept for monitoring the insulation condition of high-voltage cross-linked polyethylene (XLPE) cable systems is described. The paper is based on an actual customer case study in which our MONCABLO on-line partial discharge (PD) monitoring system is used to continuously assess the insulation condition of an underground power cable system.
Monitoring points along entire cable length
PD activity is monitored at the terminations and joints of three underground power cables, which are each 10 kilometers long. Inductive PD sensors (HFCTs) mounted on cross-bonding links are used to detect PD directly at the cable accessories. One high-precision four-channel, acquisition unit is used to collect PD data from each group of cable accessories.
Advanced analysis features pinpoint defect locations
An automated PD cluster separation technique easily distinguishes between noise and internal PD defects. To achieve this, synchronous multi-channel evaluation techniques (3PARD) are applied to identify the most probable phase of signal origin. A unique, patented technology based on dual-end statistical Time Domain Reflectometry pinpoints the location of PD defects along the entire length of the HV cables.