Repair Question about Fuses

[LoveLaika]

I'm in the middle of repairing a device, a TSP controller. I'm still kind of running diagnostics on it to make sure that it wasn't anything external, but I wanted to ask a question about fuses and how devices work at different input voltages.

This device I'm trying to fix has two input settings: one for 220 V and one for 120 V. The 220 V setting requires the use of 8A fuses while the 120 V setting uses 15A fuses, so depending on the input setting, you have to change out the fuses. If it was set to 220 V while not changing out fuses correctly, so you would be using the 15A fuse, would it still work? The fuses just cut the circuit if the amperage of the fuse goes too high, but it's not a catch-all, right? If it was connected to a power strip (220 V with a  10 A fuse), I would think that the 10 A power strip fuse would break first before the 15A fuse, but is that always the case?

[themadhippy]

I would think that the 10 A power strip fuse would break first before the 15A fuse, but is that always the case?

No,its possible the 15A fuse could blow before the 10A  it all depends on the type of fuse and the fault current.The information on how quickly a fuse blows   for a given current can be found on the  i/t graph for that type of fuse

[LoveLaika]

Thanks. The manual for the controller states that it uses slow-blow fuses (5x20), while the power strip uses a ceramic fuse. I don't know exactly what the conditions were when the power strip fuse blew. All I was told that the controller was working fine when the strip fuse blew the first time, and when it blew the second time, the power strip only had the controller plugged into it.

[LoveLaika]

I would think that the 10 A power strip fuse would break first before the 15A fuse, but is that always the case?

No,its possible the 15A fuse could blow before the 10A  it all depends on the type of fuse and the fault current.The information on how quickly a fuse blows   for a given current can be found on the  i/t graph for that type of fuse

Going back to the other case, using 220 V with the 15 A fuse meant for 120 V, the controller would still work properly, it's just at a risk of drawing more current than what it safely needs, correct? Assuming that everything is fine with the power strip, under normal conditions, the controller can draw up to 8 amps (else fuse blows), but with an incorrect fuse, it can draw more than 8 amps, which could potentially damage the equipment in the worst case.