This kind of test let you use the system for parameter optimization in an easier and automatic way (in case of model change) and, for example, to let you check one part over X in a deeper and more complete way.
The purpose of this test is to check the following:
- the minimum voltage for which the partial discharges begin to manifest themselves inside the product (Inception Voltage). This test works increasing the testing voltage.
- The voltage for which the partial discharges effect disappears with higher voltage (Extinction Voltage).
This test works decreasing the testing voltage.
The SCAN test works in this way: the voltage starts from an initial voltage (for example 500 VAC) and rise up to a final voltage in a certain time. During the ramp, the system measure continuously the current (total and resistive) and the PD and acquire the values (for the Table and for the Graphic) every decided voltage step. If the measure of PD is over a certain threshold for maximum acceptable partial discharge, the software acquires the voltage at which the event occurred like PDIV and after start to decrease the voltage to found at which value of voltage the PD is extinguished. If the PDIV voltage is not found the testing voltage will reach the final voltage (for example 1500VAC). The test then will stop. As far as extinguish value (PDEV) the process is similar. If during the ramp down there is a PD discharge near the initial test voltage or however the software arrives at its target before finding the PDEV, the PDEV result will be 0.7
In the figure in the right it is shown a graphic with PDIV (blue line) and PDEV (green line) results.