In this work, a wireless system able to test up to four Remote Terminal Unit (RTU) is shown. Each RTU establish communication with a Master Unit (MU) through a radio modem,making use of the MODBUS protocol. In this work, two kinds of RTUs were used. One of them consists of real electrical power meters, while the other one consist of a personal computer that works as an electrical power meter emulator. The Master Unit can be as far as 4 km distance from each RTU. The MU permanently runs a graphical software developed with LabVIEW ?. This software ask for information from each RTU, save this information in a file and generates a report. The information refers to the main three-phase electrical network variables, which are voltage, current, frequency, power factor, harmonic distortion and active, reactive and apparent power.