Delay charging battery after outage to stagger load on mains
I have a set of 4 UPSs - 2 x SmartUPS 3000 and 2 x SmartUPS 5000. Each has a network management card. They also have extended runtime battery packs so we usually don't have to power down equipment in a power outage, unless it's really long.
The problem I am having is that the main fuse on our floor is tripping after an outage because, when power returns all the UPS immediately switch from battery to mains and start trying to recharge the battery from mains. They do this simultaneously.
Because they each cause a certain amount of inrush current, between them, they are tripping the fuse.
If I actually turn off the individual fuse to each of the 4 units, then turn on the main fuse for the floor, then turn on each individual fuse to each UPS, then everything is fine. I get some inrush current from each but its not enough to trip the main fuse for the floor.
I have asked about changing the fuse for the floor to a slower one, but I have been told we cannot. The fuse is easily big enough to handle the load, just not when the UPSs all switch from battery to mains at the same time.
Is there a way to tell each UPS to wait a certain amount of time after power is restored before it starts takings power from the mains again?
Note, that this is in a situation where we have not had to power down equipment thanks to the battery packs. The equipment remains on, the outlet groups remain on.