A contactless three-phase autonomous power meter

Electrical energy management is becoming crucial to optimize the generation and usage of power. Therefore, measurement of parameters (such as amplitude and/or phase shift) of electrical systems is of the utmost importance for achieving efficient control on power usage of electric loads in residential and industrial buildings. Most of the existing smart metering devices available on the market need voltage probes which are invasive, because they need a direct connection with the potentials being measured. We present an innovative low-cost clamp-on power meter, designed and optimized for three-phase systems. It can be installed without temporary interruption of the supply directly on the cable insulators and can measure simultaneously both current and voltage of the underneath wires, providing accurate measurements of apparent power, active power, reactive power and power factor. Moreover an energy harvesting unit extracts the necessary energy to supply the meter without electrical contact, permitting to install the device without need of batteries or power plugs. Experimental results show the accuracy of the measurements and the autonomy of the small size and compact power meter.