Rack Organization - SURT20KRMXLT-TF5, SURT192RMXLBP2, APTF20KW01

[Anonymous user]

We've purchased the APC Smart-UPS RT 20KVA RM 208V (SURT20KRMXLT-TF5), 2 additional external battery packs (SURT192RMXLBP2), and a 20KVA Isolation Transformer (APTF20KW01).

The transformer is a beast (~250lbs), so my inclination is to rack it at the bottom of a 4 post rack that we have allocated for this installation. On top of it (on rails, of course), I was going to load the 3 battery packs and finally the UPS itself on the top.

I haven't had a chance to discuss with our electrical contractor who will be doing the install, but does this seem to be the logical organization of these components? I thought about potentially racking the transformer directly underneath the UPS unit to make the wiring runs slightly shorter, but I'm not sure if there is a real benefit there.

Is there a recommended configuration for these components?

[Terry_Kennedy_apc]

APC recommends installing the transformer at the bottom of the rack (page 11 of the PDF). They also say the UPS must be installed above the batteries (page 4 of the PDF).

Depending on the loading capacity of your rack and what type of floor it is on, this combination may or may not exceed the maximum allowable weight in the rack. I get 1700 lbs for the equipment you list - 640 for the UPS, 400 each for the 2 battery frames, 260 for the transformer.

If you have multiple racks, an option would be to put some equipment in the bottom of one rack and the rest in an adjoining rack. Here is a picture of how I did this with a Symmetra RM - the UPS is on the left with the transformer above (it is a much smaller plug-in transformer, while yours is hard-wire) and the two XR battery frames are on the right. Note that sometimes a battery pack extension cable is needed if the XR packs are not directly under the UPS. If you plan for a side-by-side installation, verify the battery pack cable length and/or the availability of an APC extension cable before ordering.

[Anonymous user]

Terry,

Thanks for the reply. I'm a bit embarassed that the information was staring back at me from the manual.

The rack we are using has a 3000lb stationary weight capacity, so we're good there. We are on the second floor though, so I'll be sure to discuss with the engineer before we load it up.

Thanks again.

[Terry_Kennedy_apc]

A number of supposedly high-capacity racks have embarassingly small feet or casters which concentrate the floor loading onto very small points. If you look at the picture of my rack that I linked in by first reply, you can see what I mean. In my case, the "floor" under the rack is actually 2 sheets of high-density 3/4" plywood glue-laminated together, laid over 4x4 cribbing which is perpendicular to the floor joists. However, these cabinets are in my [spare] residential dining room with a regular wood floor, so if you are in an office building this will be less critical. But check just to make sure.

The other concern with heavy stuff higher up in racks is that it moves the center of gravity higher. I doubt your rack is going to tip over if you slide something like a 2RU server out the front of the cabinet , but you should check to see what method is used for servicing the batteries. I doubt the whole unit slides out (instead, there are likely removable battery packs within the chassis) but if you do something like replace all of the batteries at once, you have a 640 lb UPS up near the center of the rack and mostly-empty space between it and the 260 lb transformer at the bottom of the rack, which could get "interesting".

[Anonymous user · Accepted solution]

We're in the Carribean so each floor is steel reinforced concrete that is (if I recall) 12 inches thick, but I am waiting to hear back to confirm that.

You're absolutely right about the rack - the leveling feet are pretty meager. We'll have to see how that pans out.

The battery packs have 8 batteries each that are individually servicable, but we'll be having the APC partner in-country doing our regular maintenance, so I'll leave it to them to do things the Right Way™

Thanks again for your feedback.