A fuse’s time-current characteristics determine how fast it responds to different overcurrents. All fuses have inverse time-current characteristics, so opening time decreases as overcurrents increase. Time-current characteristics are presented graphically on standardized “log-log” scales. Time-current (TC), curves are calibrated time-to-open vs. current curves for a fuse so that a circuit designer can determine how fast the fuse will open under a very specific current condition.