Indicating direction of energy flow in electric AC voltage mains especially medium voltage mains

摘要

The method involves inductively tapping the current of a mains conductor (10) and capacitatively measuring the voltage across it to evaluate the phase position of the conductor current and voltage and activate corresponding directional indicators (11,12). The phase position is evaluated with an oscillator-controlled counter of a computer (13). The computer determines the cycle duration and the duration of positive voltage input pulses that are produced in the computer with the conductor voltage. The computer accordingly computes the actual zero passage, based on the phase position evaluation.