| OWTS 150 - 250 |
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The system consists of a notebook as a WLAN control unit and a HV unit. The HV unit contains a HV source and a resonance inductor with an integrated electronic switch to generate damped AC test voltage. The HV divider and the coupling capacitor are integrated in a separate unit together with the embedded controller for the digital data acquisition and PD signal processing. The storage, analysis and evaluation of the PD signals takes place in the notebook and can be done either on site or in the office. The PD fault location is based on the time domain reflection method. For the PD diagnosis the test object is charged to the pre-selected peak value by a HV source within a couple of seconds and afterwords shorted with an electronic 150kV switch via a resonance coil. Thus a sinusoidal damping AC voltage with low damping is created (DAC). Depending on the capacitance of the test object the AC frequency varies in the range from tens to hundreds of Hz. Since the DAC frequency of the test voltage is close to nominal AC service conditions all measured PD activities can be effectively evaluated. The PD inception voltage (PDIV), PD extinction voltage (PDEV) and the dielectric losses value can be easily determined due to the decaying amplitude of the test volt-age. Critical PD levels responsible for the insulation degradation status of the cable insulation are important criteria in the evaluation. The analysis and evaluation of the typical PD parameter as well as the PD fault location supports the Asset Management for reliable decision criteria for maintenance- or replacement activities. Features
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