domains are limited according to a preferred embodiment so as to provide output data in the range of the manufacturer provided average melt curves for standard current interruption devices of the duration intervals t the minimum duration interval t min is preferably fixed at 1 8 second and the maximum is set at 4096 seconds according to a preferred embodiment of course a wide variety of minimum and maximum duration intervals are contemplated according to embodiments of the invention within the preferred range the function is evaluated over sixteen geometrically progressively larger intervals increasing from the minimum to the maximum interval by doubling 1 8 second 1 4 second 1 2 second and so on for example the resulting data set is suitable for direct visual comparison to published data for standard current interruption devices thus the several mathematical approximations are as follows according to a preferred embodiment first the maximization process is not carried out over all possible intervals t in the survey period t but rather the process is restricted to all intervals t beginning at discrete time separations t min in t second an approximation for the short term mean is made by squaring the output of the rms approximation defined by equation 12 of fig1 c further approximations arise from the inherent quantization error associated with digital sampling systems and rounding error intrinsic to digital arithmetic turning to fig2 according to a preferred embodiment precision current transformer type current probes 17 20 fluke model 80i 600a for example are coupled with shunt resistors 21 24 to provide voltages to the processing circuitry that are scalar multiples of the current flowing in the conductors.