Server Room Build Log – Backup Power


Posted on: June 4th, 2012 by Child of the Sunfish

To back up the rack, an Eaton Powerware 9125 1000va rackmount UPS will be installed. This will ensure that the security cameras and alarm system continue to function in the event of a power outage and wireless internet will still be available. The server room is on it’s own circuit, so if something trips in the rest of the house the server room will not be affected. The lighting is still part of the main lighting circuit however. If the power does go out, the UPS is fitted with an optional ConnectUPS Web/SNMP card which allows the UPS to connect to the network, which will allow the user to check the status, load % etc… from the convenience of a web browser. With the correct port forwarding, it is possible to access the status page from anywhere in the world. The other advantage of the ConnectUPS card is that it is able to broadcast to the server a shutdown message when the power goes out. This means the server will shut itself down properly and will lighten the load on the UPS will lighten, which means the cameras will be able to operate for longer.

It would be ideal for the UPS to backup the lighting circuit as well, howeer 1000va is not nearly enough power to keep a house full of lights going, so the UPS must be beefed up. The batteries shown below are 50AH each, which amount to 200 amp hours. Currently there is 18AH in the UPS, so this will be a nice upgrade.

The batteries are all new and were in service for about a month before the battery bank that they were part of was dismantled and were going to be thrown away. Removing them was a bit hairy, as there were many batteries connected in series to make 415v, so accidentally touching both active leads would have been poor form. The cables to connect them will be 10mm2 flex that will need to be lugged, heatshrunk and bolted to each battery. As the UPS is 24v and these batteries are 12v, two batteries will be connected in series in series, then connected in parallel (with the other set of two) to the UPS.

The batteries will be connected to the external battery connector of the UPS, so the UPS will see the batteries as what they are, additional banks. This will not increase the total amount of power that the UPS can output, but it will increase the length of time that it can operate.


The original UPS battery on the left, and prepping the new batteries (right)

Depending on how much load the rack requires, there may be an option to backup the C-Bus panels and lighting as well but this will need to be investigated once the UPS is installed and the rack is commissioned.