HV AC generation based on resonant circuits with variable frequency for testing of electrical power equipment on site

The overall booming industry has great need for electrical industry. Hence, electrical power generation, transmis-sion and distribution have to respond to the continuously grow-ing demand by e.g. increased transmission capacities or trans-mission voltages but also by longer transmission networks. Hereby, the more and more demanding requirements for devices of power transmission and distribution have to be fulfilled by the high voltage test equipment as well. Massive and heavy test equipment is available for factory tests, which however cannot be used for on-site tests. Therefore, resonant circuits are the only practicable test equipment solution in order to facilitate physical-reasonable AC voltage tests with the respective diagnostic equipment on-site. The specific advantages of resonant test equipment with fixed-core reactors and variable frequency tuning, which leads to a high resonance quality factor in particular, allow providing test systems with high power and robust design. The statistic con-verters, especially designed for on-site application, guarantee the wave forms of the test voltages according to the relevant stan-dards and allow PD measuring also under on-site conditions. Various test systems, well adapted to the test specifications and the characteristics of the test objects, are available. There are for instance systems on the basis of oil-cooled tank type reactors, with extremely high power which is needed e.g. for the testing of long cables, systems on the basis of gas-insulated, metal-enclosed re-actors which can be Hanged directly to GIS/GIL with test voltages of up to 1000 kV and systems optimized for induced and applied voltage testing of power transformers.