A method and a device for measuring dielectric characteristics by generating a microwave signal, dividing the signal into reference and sounding signals, irradiating a body with the microwave signal, receiving the reflected, reference and total signals and in detecting said signals. Power flow to andor from a power unit connected to an electricity distribution network is controlled in accordance with a control sequence, such that the consumption andor provision of power by the power unit results in a power flow having a predefined flow pattern, and having a characteristic, such as an amplitude, which can be remotely measured. This provides a reliable and simple method for ensuring that a mains supply may be safely connected to the motor. The multipoint processor unit also communicates with the multipoint control unit for interfacing the call signaling and the call control information between said multipoint control unit and the terminals.