Patent ID: 6185482
Filing Date: 2001-02-06
Classification: H02H

Abstract:
A method of over current backup for a system having a current signal, comprising the steps of:(a) obtaining a current measurement;(b) determining whether frequency tracking is available;(c) if frequency tracking is available, employing said frequency tracking to provide fault protection; and(d) if frequency tracking is not available, providing fault protection by performing the following steps:(e) obtaining additional current measurements until a sufficient number of current measurements have been obtained to calculate a root mean square (rms) current value;(f) generating a rms current value from said sufficient number of current measurements;(g) repeating steps (e) and (f) to generate a plurality of rms current values;(h) generating a current estimate from said plurality of rms current values; and(i) activating a fault protection mechanism if said current estimate is above a predetermined threshold.