For example, Littelfuse’s 383 series - TR5® time-lag 300V rated fuses have time-current characteristics as shown by the below graph. and other fuses. 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. In fact a 13A fuse will allow a current of 20A to pass indefinitely without blowing. The time-current characteristics of fuses are affected by ambient temperature. Replacement & post-operation: Fuse can be used only once per operation as it is self destructive. Replacement is must after completed operation. It is related to the let through energy I 2 t characteristics.. Characteristic Curve: Fuse characteristic curve shifts because of the ageing effect. If we look at the graph in Fig 1, it shows the operating characteristics for both 3A and 13A BS 1362 fuses. Melting Integral I2t Rating: ... Time-Current Characteristics curve. The I 2 t characteristic of the short time function determines the delay type. Circuit breaker characteristic curve doesn’t shift. Fuse Time Current Curve. https://electrical-engineering-portal.com/fuse-characteristics-protection-circuits I 2 t IN will result in an inverse-time delay that resembles the time/current characteristics of fuses. To start our discussion on common overcurrent protection devices, let us review the basic considerations of a coordination study. Figure 3. Also, fuses have an inverse time-current characteristic, which means the greater the overcurrent, the faster they interrupt. 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. It also contains equation parameters for E-speed, T-speed, Tap, Main, IEEE, and IEC curves. A fuse’s time-current characteristics can help. This does not factor-in the heat from a populated fuse Higher the ambient temperature, the hotter the fuse will operate and it shorter its life. TC curves… 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).. Kearney offers six types of fuse links with a wide range of time-current characteristics (refer to Table 1). This is similar to the long time function except with a much faster delay. 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