As part of the grid simulator devic

As part of the grid simulator device, the short-circuit emulator is used to create the voltage drops due to short-circults between the two or three phases, or between one or two phases to ground, via the impedance network Z1 and Z2 as shown in the test device layout in figure 2.The impedance Z1 is used to limit the effect of the short circuit on the utility service that powers the test circuit. The sizing of Z1 shall therefore account for all test sequences to be performed and limit the short-circult current taken from the grid to values that do not cause an excessive reduction of the grid voltage. Considering an acceptable voltage reduction of at most 5% when performing the test, the minimum value of Z1 shall be at least 20*Zgrid, when Zgrid is the grid short-circult impedance measured at the test circuit connection point.To ensure that the test is realistic, however, the apparent short-circult power (SEUT) available at the equipment under test connection node NEUT should be at least equal to 3*Pn, where Pn is the rated power of the equipment under test (minimum value SEUT>3*Pn, recommended SEUT=5 to 6*Pn). This means that during the short-circuit tests, the contribution of current through Z1 and Z2 form the grid remains dominant compared to the current contributed by the equipment under test. In this way, the inverter current does not create a significant voltage rise for the duration of the test relative to the no-load drop.