BASIS-These fuse links are tested in accordance with the ... than 200% of fuse-link ampere rating, and the minimum melting and total clearing curves are based on tests starting with the fuse link at an ambient temperature of 25°C (77°F) and no initial load. The time-current characteristics of fuses are affected by ambient temperature. A fuse’s time-current characteristics can help. Melting Integral I2t Rating: ... Time-Current Characteristics curve. To start our discussion on common overcurrent protection devices, let us review the basic considerations of a coordination study. It also contains equation parameters for E-speed, T-speed, Tap, Main, IEEE, and IEC curves. If we look at the graph in Fig 1, it shows the operating characteristics for both 3A and 13A BS 1362 fuses. ... A typical fuse time-current curve is shown below. This is similar to the long time function except with a much faster delay. The selectivity limit current is the value at which the let-through energy I 2 t of the circuit-breaker exceeds the pre-arcing I 2 t of the fuse (curve or value provided by the manufacturer).. Characteristic Curve: Fuse characteristic curve shifts because of the ageing effect. This does not factor-in the heat from a populated fuse I 2 t IN will result in an inverse-time delay that resembles the time/current characteristics of fuses. Cable Damage Curves: Cable damage curve shows that how much current a cable can carry without insulation damage and for how long it … MICRO3 Fuse Time-Current Characteristics 3 5 7.5 10 15 Time-Current Characteristic Curves Blade Fuses Dimensions Dimensions in mm Temperature Rerating Curve *Component Level Temperature = the maximum ambient temperature that a single fuse will survive. Also, fuses have an inverse time-current characteristic, which means the greater the overcurrent, the faster they interrupt. Fuse Time Current Curve. The higher the ratio, The grey shaded area is the point where the fuse is designed to operate. Replacement is must after completed operation. Kearney offers six types of fuse links with a wide range of time-current characteristics (refer to Table 1). TC curves… The I 2 t characteristic of the short time function determines the delay type. Understanding overcurrent protection device characteristics is very important in a protection coordination study. and other fuses. Higher the ambient temperature, the hotter the fuse will operate and it shorter its life. Figure 3. Replacement & post-operation: Fuse can be used only once per operation as it is self destructive. Vista Overcurrent Control 2.0 Time-Current Characteristic (TCC) Curves Information Bulletin 680-211 contains curve plots for all Vista Overcurrent Control 2.0 TCCs. The speed ratio of all fuse link sizes 100 A and below is the ratio between the current that melts the fuse in 0.1 seconds to the current that melts the fuse in 300 seconds. For example, Littelfuse’s 383 series - TR5® time-lag 300V rated fuses have time-current characteristics as shown by the below graph. In fact a 13A fuse will allow a current of 20A to pass indefinitely without blowing. It is related to the let through energy I 2 t characteristics.. Circuit breaker characteristic curve doesn’t shift.