Patent ID: 9030795
Filing Date: 2015-05-12
Classification: H02H

Abstract:
1. A method of providing electronic overload protection having a thermal trip level, said method comprising: executing a function by a processor; providing said electronic overload protection by said function executed by said processor; adjusting the thermal trip level by said function executed by said processor in order to mimic adjusting a physical thermal characteristic of a thermal time constant of a fixed mechanical system; employing a current transformer as said fixed mechanical system; employing at least one of: thermal mass surrounding the current transformer, and thermal resistance from the current transformer to a shunt conductor as said physical thermal characteristic; sensing the temperature of a shunt conductor having a predetermined fixed impedance and a thermal mass; tripping a circuit interrupter at a variable temperature employing a trip time delay determined by the thermal mass of said shunt conductor; and adjusting the variable temperature as a function of current flowing through said shunt conductor having the predetermined fixed impedance, wherein said function of current flowing through said shunt conductor includes subtracting measured current flowing through said shunt conductor, as a percentage of rated current of said circuit interrupter, from a predetermined constant.