Patent ID: 6765776
Filing Date: 2004-07-20
Classification: H02H

Abstract:
An electrical power distribution system, comprising:a solid state switch element having a control input and a load line for supplying current to a load, the solid state switch having a sense output for sourcing a sense current which is fractionally proportional to the load current; a switching controller having a control output connected to the control input of the solid state switch element and a sense input connected to the sense output of the solid state switch element; data processing means associated with the switching controller for storing and executing a direct current equivalent estimation routine, a load current threshold value, a heat index routine and a accumulated heat index threshold value; and the data processing means using the sense current as an input for developing a direct current equivalent estimate of the load current, for further comparing the direct current equivalent estimate to the load current threshold value, for executing the heat index subroutine using the load current root mean square estimation as an input, responsive to the direct current equivalent estimate exceeding the load current threshold value for accumulating the results of execution of the heat index routine and further responsive to the direct current equivalent estimate falling below load current threshold value, for applying a decay factor to the accumulated results.