Connecting a ups to a ups

[JamesGled]

We have a small data centre with SRT300, these have two power supplies one connected to an AP4423 apc power switch which is connected to the rack power untis and the other connected to to a wall circuit which I have been advised is connected to a larger UPS. 

If there is a powercut will the bigger UPs 

If the rack mounted SRT300 battery has failed will the bigger UPS be able to keep the racks running.  On one hand I have read that it is not possible for the bigger UPS to move power to another UPS

[Teken]

You’ll need to restate your question as it doesn’t make any sense. If I try to decipher what your asking than this leads to more questions for you to provide an answer to.

You also need to understand the basics of what the three devices are tasked to do.

1. I’ll start with the obvious one which is the AP4423 is a ATS (Automatic Transfer Switch). It’s only job is to transfer power to another input power source (B) if the primary input (Source A) has been lost.

2. Wall Outlet: I’m going to assume this wall outlet is a protected circuit. This typically in a real enterprise environment means that circuit is protected and powered by a back up (Generator). 

It’s not a UPS . . . 

3. SRT3000: If I take what you stated literally as to (IF) the SRT3000 failed. Everything connected to it like servers will either power down or lose power.

Obviously this is dependent upon the failure mode! If it’s a depleted battery cartridge the system will resume (if programmed) upon AC restore.

If the UPS has failed internally all the connected loads will not resume upon AC restore.

As to your question as to (IF) the wall outlet can handle the load only testing and validation can determine this! ☝️

Lastly, do not mistake a ATS vs a Maintenance Bypass Switch as the same!

Questions Ask . . . 👍

[MorneMeintjes · Accepted solution]

Good Morning

From my understanding is that your ATS is supplied by two UPS systems. One in the rack, and the other via a bigger UPS via the wall circuit. For example If the small rack UPS is connected to the A source of the ATS and the Bigger UPS to the B source, Then the ATS will select the best source of power. If the small UPS fails the ATS will switch to the larger UPS. The larger UPS does not supply the smaller UPS, Unless its also fed from the same wall circuit. however with the larger UPS outside of your control, I would suggest testing to make sure that the wall circuit is fed from a UPS, and that the larger UPS is able to cope with the additional load. In addition if the larger UPS exists and is working.

Hope this helps

Best Regards