Stacking UPSs

[kevinturcotte]

Is it safe to plug a UPS into another UPS? I already have 1, and am trying to increase backup time, but would be great if I could also use my current UPS.

[davring]

I would split the load and run them independently. The ineffeciency of one running another would be very high.

[premio]

Is it safe to plug a UPS into another UPS? I already have 1, and am trying to increase backup time, but would be great if I could also use my current UPS.


It is safe and fine to do. You loose some overall battery time on the 1st UPS, I believe if they both are running on battery, it still pulls 10% of the daisy chained load on the first. It also creates more load while on AC for the first one, which can cause a problem if you are getting towards the peak amount of amps its capable of drawing. I have some server racks setup this way, and although it is not optimal, it works.

-n

[old7]

I would say that it depends on the type of UPS that you are using.

Daisy Chaining UPSs (http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_sid=uz6B5zsh&p_lva=&p_faqid=397)

In most cases, daisy-chaining UPSs does not allow for extra run time. If you are using a UPS that outputs a step-approximated sine wave when on battery, as soon as the fist UPS goes on battery, the second UPS will also go on battery because it will see the step-approximated sine wave as distorted or bad power. Both units will discharge together, and will not provide any extra run-time to the load.

[SubaruWRX]

cool always wondered about that.