On-Site Test After Laying with AC Voltage of Significant Lengths of HV and EHV XLPE Cable Systems

摘要

Test after laying of significant lengths of high-voltage and extra-high-voltage polymeric cable and accessories serves as a diagnostic tool to help network owners prevent unexpected outages. The purpose of such testing is to detect defects in assembled accessories. Sheath testing using DC is always necessary. Quality assurance is important but will not be able to eliminate all defects caused by bad workmanship. For polymeric cables, DC testing is dangerous and ineffective, whereas AC testing is effective and practicable. Series resonant test equipment is now available. Up to 20 MVA reactive power per test set can be realized on one trailer. HV-XLPE cable systems (50-150 kV) can be effectively tested using 2.5Uo 10-15 minute test voltage. System lengths of up to 25 km can now be tested. EHV-XLPE cable systems can be tested using at least 1.7Uo 1 hour. 400-kV systems and GIL can be tested in lengths of up to 6.5 km. Over the last ten years, a lot of experience has been gained in Europe and South Africa. The standards are still behind the current practice. This causes a lot of confusion. In future, partial discharge measurements should be integrated with the AC voltage withstand test method. The effectiveness of the method will be further improved.