| Highvolt Pr�ftechnik Dresden GmbH, Germany, is a leading and reliable high-voltage (HV) test equipment supplier for today�s cable industry and suitable for both manufacturers and users of power cables. At the end of the 1990�s, the company developed and introduced a new series of resonant test systems for after-laying HV tests on long HV and EHV cables. These test systems are mainly featured by the appliance of HV reactors with fixed inductance tuned to the system frequency by a static frequency converter in the range from 20 to 300Hz, in accordance with the valid standards (such as IEC 60840 or IEC 62067) and recommendations (such as CIGRE Task Force 33.03.04) for on-site tests.
The company�s success in this field activated further applications of the resonant test systems with variable frequency (ACRF) for the cable industry. Today, the company offers its new ACRF systems, series WRV, rated up to 50kV testing voltage and 25A testing current. This new WRV series enables HV tests on XLPE-insulated cables up to 50km length. The mobile and very stable designed equipment can be installed in a standard van. The test system combined advantageously the real HV AC withstand tests with application of different diagnostic tools such as partial discharge and dissipation factor measurement. That testing method reflects operational conditions better than all other known testing procedures and offers most efficient and realistic measurements.
Meanwhile, there is a clear tendency to manufacture extremely long power cables from one piece for special applications (such as submarine cables). Cables much longer than 50km are already manufactured and cable lengths up to 200km are under discussion. Such long cables cannot efficiently be tested with conventional HV AC testing equipment due to the enormous testing power demand. Therefore, these cables are tested with ACRF systems in factory at frequencies down to 20Hz, in contradiction to presently valid standards for routine testing (45 to 65Hz). Highvolt Pr�ftechnik has supplied an ACRF system for 400A, 110kV.
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