AX850 PSU doesn't start when connected directly to BR1500-IN

[Anonymous user]

Hi guys, I have a APC Back-UPS RS 1500 and Corsair AX850 in my rig. Yesterday I noticed that when I connected the power supply cable directly to UPS, it doesn't power on. But when I connect a Belkin Surge Protector to UPS and then connect SMPS cable to surge protector, it does start.

Why would this be happening. I don't want to use surge protector with UPS as it is not recommended. Another thing to notice is when my Back-UPS runs on battery in cases of power failure, I hear a humming sound from PSU.

[BillP]

Can you clarify, when you connect your power supply to the UPS, is the UPS online (passing utility power through it) or is it operating on battery power (either because you have it unplugged or you're doing this while running a self test). Seems like the answer is while it is online since you talk about humming while the UPS operates on battery.

This UPS outputs a step approximated sinewave while on battery so humming because if this can be seen if the power supply does not like the step approximated sinewave.

[Anonymous user]

1. When UPS is online (passing utility power through it), PSU doesn't power on at all when connected directly.

2. When UPS is online (passing utility power through it) and there is surge protector connected to it through which PSU is connected, PSU starts normally (without humming sound)

3. When UPS is offline (providing power backup from it) and there is surge protector connected to it through which PSU is connected, PSU operates with humming sound.

So for the humming sound part, you are saying that is normal right? And if I am using backup only for maximum 5 mins worth of time just to shut down the machine, it wouldn't damage anything.. right?

[BillP]

Well, I did find this -> AX 850 with non-sine UPS - The Corsair Support Forums

It seems that they do not recommend Back UPS (not pure sinewave) UPSs with this type of power supply.

Did this ever work for you or is it a new install?

[Anonymous user]

Really shame on both Corsair and APC. Shouldn't both of you have a conrete information available somewhere about the compatibility.

Corsair guys are suggesting to ask APC guys in the thread you are suggesting. So can you please let me know if APC has done any testing on AX850 with the UPS I am using?

Also let me know which pure sinewave UPS does APC manufacture ?

[BillP]

I will have to get back to you tomorrow on the testing since I am not directly involved. I was just pointing out that it does not seem like a step approximated sinewave is recommended by Corsair but I will see what we've tested. As I hope you can understand, I can't imagine that every vendor (Power supply and UPS) has tested every single possible combination of power supply and UPS that exists out there.

Our pure Sinewave UPS models are Smart UPS -> http://www.apc.com/products/family/index.cfm?id=165

We also have a UPS out there that deals better with PFC power supplies and I'll see about that too.

[BillP · Accepted solution]

Ok, here is some additional information that I obtained.

There certainly are PSUs out there that do not like Step Approximation as it is generated through solid state components, as opposed to natural generation. We have begun to develop some smaller units with a quasi sinewave output, which is much closer in size and quality to a pure sinewave, however this modification has not yet reached the -IN product families.

Regardless, the initial description of events when connecting your PSU seem odd. If the PSU is not powering on when the UPS is online, it's possible the inrush of the device is causing an Online Overload condition.The addition of the surge strip is potentially limited this inrush, in turn allowing the PSU to power up without triggering the Online Overload. Just a guess based on what you've said so far but beyond that, we cannot think of any other reason for this strange observation.