Abstract: To minimize the outlay for circuit engineering in a measuring system having at least one measuring instrument for measuring power and/or power factors at least one measuring point in an a.c. voltage network, a voltage transformer device having in each case one voltage transformer for each phase of the a.c. voltage network is arranged at a voltage-detection site of the a.c. voltage network. In addition, a current transformer for each phase is arranged at each measuring point, and to connect a measuring instrument assigned is connected to the particular measuring point at a current transformer input. The voltage transformer device and all measuring instruments are interconnected via a shared data-transmission device, in which predefined information on the detected voltages is digitally transmitted to the measuring instruments.