Question

a transformer is feeding a street light. on the secondarily of transformer is a fuse holder with a 10A fuse and also on bottom of street pole there is another 10A fuse.. the light went out and i found a fuse by transformer blown. im cunfuse why the first one by the light did not blow but the one by transformer did

Answer 1

Page- Ans: Let, Fuse of tlf - I lood Is fuse-1 = fuse at transformer Side fuse-2= fase at Load side. Tegno om للمعايا انا light with transformer fuse protection) figue- According to your question, light went out due to high current and fase of street pole where Light is placed was not blown but the fuse at transformer side is blown off. why this happens because, 0. fuse is melt-down when higher than rated - current flows through it." . fuse take a "small amount of time" to metta -out when more than rated current flows through it. ③. first for Primerly, when there is beavy current - flows from secondary side of transfer at

time it';, the transformer fase will not blown immediately at time t, it take a little amount of time (ie, in the order of nano-seconds) to melt-out, In this mono-seconds time Period the current flows from transformer secondary side to street light lood fuse at time to the street light load fase also not meltout at t seconds and it takes some time (tzt nano, seconds) to melt-out fuse. S so the heavy current will flows through the street light and it is blown-off at te seconds time. Here (t >tz) t=time to reach high current en fisse op transformer. At nano cong) a time to me . fusa te=time to reach hay current to o the load side fuck So, when the current reaches to load side, the fuse of transformer starts to heat and reaches its metting point, so therfore the transformer fuse is blowntoff, and light is also blown-off.

when transformer fuse is blown, there is immediately no current through the fuse-2 (fase at lood side), so the fuge cool down and not blown undo this situation,