Mains Power Issues with 3550 Inline Power?

[ADB100]

We have had a few PSU issues with some Catalyst 3550-24 Inline Power switches. It seems several of the internal Switch Mode PSU's have gone pop. Not a big issue really since this is likely to be the first thing that goes bang anyway? The problem is we have up to 3 of these switches connected to a APC UPS 3000, when the PSU goes it takes the 20-Amp C-Type input breaker of the APC UPS with it (this leaves the UPS running on batteries for a few hours until they have discharged as the mains input has 'tripped'). We have checked and there is a 10-Amp fuse in the 3550 switch and I would have thought this would blow before the 10-Amp input breaker to the UPS?

This is what appears to be happening and APC are questioning the Catalyst 3550. I would have thought the UPS(UPS's as there are loads of them....) was at fault? My electrical theory is non existent so any pointers as to what this is likely to be would be helpful. APC say the outputs on the UPS are not fused.

Thanks

Andy

 

[JJDiver]

I wonder if the 10 Amp breaker is a slow blow? Might check it.

I would have thought the PSU on the Cisco switch would last a bit longer than you are seeing, is there an overload on the PSU?

Just guessing,

Jeff

 

[ADB100]

Out of about 200 or so switches we have had about 5 or 6 PSU's that have gone pop, its not a major issue in my eyes but it possibly will turn into one....... The breakers on the input to the APC UPS are 20-amp C-Type's (the different types (A, B, C etc) relate to the surge they will handle I think?).
Anyway, as I said what appears to happen is the Catalyst 3550 PSU goes pop and for some reason there is a surge in current through the UPS and this trips the breaker. I haven't checked if the internal fuse in the switch has blown but I presume it has (don't know what type of fuse it is as it is soldered to the board). None of the outputs from the APC UPS (SURT3000RMXLI) are fused and each of the 8-outputs are standard female IEC sockets.
There has been some speculation that each of the outputs should have a fused cable? Where you can get a male-to-female IEC cable that is fused is a mystery to me? but this was a comment from APC?

Any more suggestions welcome?

Thanks

Andy