In combination with the voltage transformer VT2, the maximum output voltage of the ARTES test systems can be doubled from 300 VLE/520 VLL to 600 VLE/1040 VLL. So it is possible to directly test protection relays with a rated voltage of up to 690 VLL.
The 3-phase voltage transformer VT2 is characterized in particular by its high accuracy. But also the protection of the test object against overvoltage was specially considered.
During the development of the VT2, special attention was paid to the dimensioning of the transformers. Their special adaptation with regard to windings, iron cross-section and geometry made it possible to achieve high voltage stability and thus high accuracy over a wide load range. Time-consuming measurements and the determination as well as entering of the respective transformation ratio before each test can therefore be dispensed with in most cases.
The inrush current common when using transformers can lead to incorrect measurement results during the protection relay testing. Due to the number of windings and specially designed transformer cores, extremely effective inrush elimination could be realized. Constant output voltages are available directly at the start of the test and guarantee precise measurement results.
Overvoltages can occur at the output of transformers when the input voltage is switched off due to the change in magnetic flux. The voltage peaks can reach values that may cause damage to the test object. The VT2 therefore has a special protective circuit that limits any voltage transients at the transformer output without reducing its accuracy.