Circuit detecting phase currents in multiphase system - uses one measurement resistance and signal processing circuit fed by controlled switching for reduced costs

摘要

A circuit for detecting phase currents in multiphase systems contains a current detector in each a.c. circuit with a rectifier which converts the sinusoidal signal into pulsed form and a measurement resistance. The current detectors are short circuited at defined intervals within a measurement cycle by switches (3-5) controlled by a measurement and control device (21). The currents of all phases (L1-L3) are detected by a measurement resistance (2) which only carries the current for the phase whose detector is not short circuited. USE/ADVANTAGE - Esp. for electronic trip switches. Costs less than conventional circuit and uses one measurement resistance and one signal processing circuit for all phases.