Another blown fuse in SU3000

[Anonymous user]

Have one of some SU3000 at different sites up and running since early 2017. During a power outage on one site the ups turned off as configured and expected. After power has been restored the UPS didn't come back due to a blown fuse in the distribution box. Bringing the fuse back by hand, the UPS turns on again with all the attached devices. This issue can be reproduced using the same fuse or another one in the distribution box. The fuse we're using here in Germany is standard model with 16 amps.

What may the cause? The UPS power supply? The power cord (can't believe)? Other?

Thanks, David

[BillP]

Hi David - 

Can I get the exact model and serial number of your Smart-UPS? Are you using Network management Cards or Powerchute Business Edition? If so, have they logged any faults?

[Anonymous user]

Hi Liam,

Model is SMT3000RMI2U, SN AS1616164956. We're using NMC2 with PCNS (no Business Edition). And no, there are no suspicious log entries.

[Anonymous user]

Any news regarding this issue. We don't want to wait for the next unexpected power outage...

[BillP]

Hi David,

Under the usual 230V input conditions, a 16A breaker would already be a borderline choice for the SMT3000RMI2U, due to the UPS internal power consumption and charger. On top of this, the lowest acceptable input voltage for online operation for the SMT3000RMI2U is 160V. As input voltage decreases, current draw increases in order to deliver the same power to the load, so for example, at full load, this UPS could end up drawing 3000VA/160V=18.75A + additional internal power consumption. A 20A upstream breaker, or fuse, is recommended, even if the circuit is dedicated to feeding the UPS only.

[Anonymous user · Accepted solution]

Hi Szabi,

thank you very much for your response and the explanation! I really would like to find this in the manual! Will contact APC Germany for a statement.