Trip unit input method and device using a multiple conductor current transformer

摘要

A trip unit input circuit configured to generate a signal proportional to current in respective phase lines of a power line and to provide operational power from a corresponding primary current transformer, the circuit comprising: a current sensor circuit configured to provide an output signal indicative of current flow through a respective phase line; a secondary current transformer in operable communication with the corresponding primary current transformer; and a power supply circuit coupled to an output winding of the secondary transformer, the power supply circuit being isolated from the current sensor circuit by the secondary current transformer.