AC resonant test systems of variable frequency have proven efficiency and reliability in on site testing of HV cable systems. For this, EMELEC is equipped with an AC high voltage unit for the on site testing of XLPE insulated cables, cable accessories and gas insulated switch gear transmission lines (GIS).
Since the system is PD free, it can be combined with partial discharge measurement. The test set up has a capability of testing with rated voltage of 400kV. It is also possible to test short cables with capacitance magnitudes below 10 nF by using additional coupling capacitor.
PD measurement is a complement to AC high voltage testing.
It is one of the most important non-destructive methods to detect insulation faults at cable network.
The recording, location and evalulation of partial discharge (PD) inside the cable insulation (including within high voltage cable joints and terminations) offers the possibility of an early diagnosis of cable network failure.
Test set-up consist of 20 kVA current transformer and power analyser. Minimum 50 A applied to each phase of the HV cable by current transformer. During the test, K-factor value and line impedance calculatıons made and given as a written report by power analyser.
Test set‐up consist of 200A microohmmeter. Conductivity resistance of the cable is measured and calculated according to length of the cable per km.
Test set‐up consist of 15kV megaohmmeter. Insulatıon resistance of the cable is measured and calculated according to length of the cable per km.
Test set‐up consist of 25kV megaohmmeter. Voltage is applied to the screen wires of the cable and leakage current measured.
Phases are short circuited from on side and sequences are checked from other side one by one with ampermeter.
Capacitance of the cable is measured and calculated according to length of the cable per km.