Method and apparatus for comparing load current in an electrical circuit with the capacity of its supply source

A current profiling apparatus for plotting peak RMS current in an electrical distribution system over multiple different-length time intervals, the apparatus comprising:

• a monitor coupled with the electrical distribution system to simultaneously monitor current flowing in the electrical distribution system over a plurality of different-length time intervals;
• a processing unit coupled with the monitor to output peak-magnitude current values in the electrical distribution system for each of the plurality of time intervals;
• and
• an output device coupled with the processing unit to generate a current profile showing actual peak-magnitude current values for the plurality of time intervals.

A method of analyzing load currents in an electrical distribution system to anticipate potential overcurrent conditions for a current-limiting device in the system, the method comprising the steps of:

• (a) monitoring an RMS current value of a load current in the system over a plurality of time intervals, at least two of the time intervals being of different lengths;
• (b) determining a peak-magnitude RMS current value for each time interval;
• (c) developing a system current profile using the peak-magnitude RMS current value for each time interval, the system current profile being comparative to a curve reflective of the potential overcurrent conditions for the current-limiting device in the system, including plotting the peak-magnitude RMS current values versus each of the time intervals to create a profile curve;
• and
• (d) directly comparing the profile curve to an average melt curve for a current interruption device to analyze any overcurrent conditions for the current-limiting device in the system.