Fuse change danger

mapj1:

Ah yes - the blowing of the fault to clear by repeated thumping...  Not nice, but recognised in certain circles.

There are machines that more or less do that for you, and you can use acoustic searching - think some microphones listening for the bang at the fault end. . . 

It is actually more scientific than that. If you can get the fault to flash over when you discharge the tester into the cable, at the fault you will have an acoustic pop and a magnetic impulse (from the current flow). The acoustic signal travels at the speed of sound, the magnetic impulse travels more or less at the speed of light. At our location, if we can measure the time difference between the magnetic and acoustic signals arriving, we can calculate the distance we are from the fault to within a cm or two. 


Regards,


Alan. 

mapj1:

Ah yes - the blowing of the fault to clear by repeated thumping...  Not nice, but recognised in certain circles.

There are machines that more or less do that for you, and you can use acoustic searching - think some microphones listening for the bang at the fault end. . . 

It is actually more scientific than that. If you can get the fault to flash over when you discharge the tester into the cable, at the fault you will have an acoustic pop and a magnetic impulse (from the current flow). The acoustic signal travels at the speed of sound, the magnetic impulse travels more or less at the speed of light. At our location, if we can measure the time difference between the magnetic and acoustic signals arriving, we can calculate the distance we are from the fault to within a cm or two. 


Regards,


Alan.