Device for measuring the network impedance of an electric supply network in the form of a multi-phase network, having: an excitation signal generating device, a load, a response signal measuring device, a phase switching device, an evaluation device; wherein the excitation signal generating device is configured to output an excitation signal across the load onto an interlinked phase pair (113, 123; 113, 133; 123, 133) of the electrical supply network, wherein the response signal measuring device is configured to measure a response signal induced by the excitation signal, wherein the phase switching device comprises a first controllable semiconductor arrangement and is configured, after measurement of a response signal from one interlinked phase pair (113, 123; 113, 133; 123, 133) to switch to another interlinked phase pair, wherein the evaluation device is configured to determine the network impedance (112, 122, 132) of the non-interlinked phases (111, 121, 131) of the electrical supply network on the basis of the response signals and of the excitation signals of the corresponding interlinked phase pairs, characterized in that the first controllable semiconductor arrangement of the phase shifting device has a bridge circuit consisting of four TRIACs, each in the form of two antiparallel connected thyristors (30, 37; 30, 38; 30, 39; 30, 40), wherein a first TRIAC (30, 37) is connected to a first bridge connection point, wherein a second TRIAC (30, 39) is connected to the first bridge connection point, wherein a third TRIAC (30, 38) is connected to a second bridge connection point, wherein a fourth TRIAC (30, 40) is connected to the second bridge connection point, wherein the four-pole output of the bridge circuit formed by the four TRIACS (37, 38, 39, 40) can be connected to the electrical supply network by two output nodes (124, 144) of the bridge circuit being connectable to one input node (113, 123) each of the electrical supply network, while the other two output nodes of the bridge circuit are combined to form a common output node, which is connectable to a third input point of the electrical supply network, wherein the excitation signal generating device consists of two contrary serially arranged second semiconductor arrangements (11, 15), wherein the excitation signal generating device is arranged between the first bridge connection point and the second bridge connection point. an excitation signal generating device, a load, a response signal measuring device, a phase switching device, an evaluation device; wherein the excitation signal generating device is configured to output an excitation signal across the load onto an interlinked phase pair (113, 123; 113, 133; 123, 133) of the electrical supply network, wherein the response signal measuring device is configured to measure a response signal induced by the excitation signal, wherein the phase switching device comprises a first controllable semiconductor arrangement and is configured, after measurement of a response signal from one interlinked phase pair (113, 123; 113, 133; 123, 133) to switch to another interlinked phase pair, wherein the evaluation device is configured to determine the network impedance (112, 122, 132) of the non-interlinked phases (111, 121, 131) of the electrical supply network on the basis of the response signals and of the excitation signals of the corresponding interlinked phase pairs, characterized in that the first controllable semiconductor arrangement of the phase shifting device has a bridge circuit consisting of four TRIACs, each in the form of two antiparallel connected thyristors (30, 37; 30, 38; 30, 39; 30, 40), wherein a first TRIAC (30, 37) is connected to a first bridge connection point, wherein a second TRIAC (30, 39) is connected to the first bridge connection point, wherein a third TRIAC (30, 38) is connected to a second bridge connection point, wherein a fourth TRIAC (30, 40) is connected to the second bridge connection point, wherein the four-pole output of the bridge circuit formed by the four TRIACS (37, 38, 39, 40) can be connected to the electrical supply network by two output nodes (124, 144) of the bridge circuit being connectable to one input node (113, 123) each of the electrical supply network, while the other two output nodes of the bridge circuit are combined to form a common output node, which is connectable to a third input point of the electrical supply network, wherein the excitation signal generating device consists of two contrary serially arranged second semiconductor arrangements (11, 15), wherein the excitation signal generating device is arranged between the first bridge connection point and the second bridge connection point.