METHOD AND DEVICE FOR APPROXIMATELY DETERMINING VOLTAGES AT A HIGH-VOLTAGE SIDE OF A TRANSFORMER

The invention relates to a method for approximately determining voltages at a high-voltage side of a transformer (4) on the basis of measured voltages at a low-voltage side of the transformer (4). The method comprises the following steps: measuring delta voltages (u[delta]) and phase voltages (u[gamma]) and phase angles ([phi][gamma]) at the low-voltage side of the transformer (4); transforming the phase voltages (u[gamma]) and phase angles ([phi][gamma]) into positive and negative phase sequence system voltages (u*+, u*-) and phase angles ([phi]*+, [phi]*-) of the positive and negative phase sequence systems, respectively, at the low-voltage side; determining positive and negative phase sequence system voltages (u*+, u*-) and phase angles ([phi]+, [phi]-) of the positive and negative phase sequence systems, respectively, at the high-voltage side from the positive and negative phase sequence system voltages (u*+, u*-) and phase angles ([phi]+, [phi]-) of the positive and negative phase sequence systems, respe