Controlled power-up scheme for an electronic trip unit, and circuit interrupter employing same

Abstract

A power supply circuit for a trip unit of a circuit interrupter includes a current transformer, a startup circuit receiving a regulated voltage and a DC/DC converter. The startup circuit is structured to: (i) burden the current transformer with an impedance approximating the trip unit and cause the DC/DC converter to enter the shutdown mode when the regulated voltage is below a predetermined value, (ii) remove the burden and cause the DC/DC converter to exit the shutdown mode and provide power to the trip unit responsive to the regulated voltage reaching the predetermined value, and (iii) remove the burden and cause the DC/DC converter to exit the shutdown mode and provide power to the trip unit responsive to a rate of change of the regulated voltage being at least a predetermined level.

Dependencies are inferred from the claim text.