Letting a UPS fail

[malachi constant]

A client had installed a central UPS (80kW, 480 in:208 out) when their facility was built ten years ago. The UPS backs a number of data closets. They called me because batteries have been replaced once and were starting to fail again.

I was surprised to see such a large UPS in a facility of this type and figured the replacement could be downsized. In calling the Client's technology director to confirm he was surprised to learn they even HAD a central UPS, as he had been supplying rack-mounted units for the past ten years. He agreed that him supplying a handful of inexpensive rack-mounted units is preferred to replacing the big boy.

So I need to make a recommendation to the Owner. I am thinking that is to replace the UPS with a step down transformer. But what are the consequences of letting the UPS die a slow death - if we yank out the batteries and just let the internal transformer do its thing? I suppose it could do funny things when the power dipped or went out, maybe there is some way to lock it in the bypass position? I know this is not the perfect world solution, but if I can save them from buying a new transformer since they already have a perfectly good one stored in that UPS...why not?

Any thoughts are appreciated. Thanks!

 

[GoldDigger]

First, does the unit actually have a transformer that normally bypasses the active UPS components?
If it is a dual conversion unit in which the inverter is the only source of output AC unless manually bypassed, then you may not be able to operate at full power or supply surges without the batteries in circuit.
If you can manually bypass the charger and inverter, then I see no reason not to just flip that switch and leave it that way.

 

[malachi constant]

Appreciated. That gave me the confidence to call up the UPS vendor, he believes it can stay in permanent bypass and that the transformer & equipment (with batteries removed) should last 20+ more years. He's confirming before we tell the Owner. Thanks!

 

[GoldDigger]

Just be careful to confirm that it is not serving any legally required loads. If it is, you will have to install suitble backup for them first.

 

[ron]

The central unit might be in a better temperature environment than the rack UPS's and depending on the UPS and battery type, you might get better performance and lifetime out of the central unit.
Batteries like to be at 77degF, and rack UPS's are usually cheaper and only last 2-3 years. Rack UPS's are often not double conversion and offer less coverage for power quality events as compared to a rack unit.

 

[malachi constant]

Funny story, part of the reason they called us was because the central UPS was located in a room without significant cooling, which contributed to the battery failure. One option was to relocate the new central UPS to one of the data rooms, which had adequate space and cooling capacity to handle it. Another option was to replace the UPS in place and add cooling to the existing room.

Pretty crazy...

 

[GoldDigger]

Have they considered the need to provide backup power for the data center cooling as well as the equipment?!
Otherwise they may need to shut down their data processing even before the batteries run out.

 

[Haji]

What about moving only the (sealed,maintenance free) batteries of the central UPS to the data rooms to reduce the cooling load?