Change in resistance of aircraft current limiters and its effect on current division in networks

When an aircraft current-limiter element is subject to sufficient overcurrent, it heats and finally melts, thus interrupting the circuit. The ohmic resistances of limiters at the instant before melting have been measured in the laboratory and have been found to be about 5.2 times the cold resistance, for copper-element limiters, and about 4.2 times the cold resistance for silver-element limiters. This increase in resistance results in an equalizing effect in parallel-connected limiters. A method is developed in this paper for predicting the extent of such current-equalization; in addition, it was discovered that the present method of predicting whether a limiter is damaged by a given current transient appears conservative.