UPS Sizing for Networking Equipment

[Senselessticker]

I have a client who wants a recomendation for UPS loading. Currenty some computer networking equipment is supplied by two in-line 6.3kVA units. Input to the UPS units is 208V single phase, output is 120V single phase. I requested nameplate information for all of the equipment being fed from the units. Total load (from the equipment nameplates) is 105 Amps. However, the "network guy" tells me that the actual combined load is a steady 18.3 Amps (information gathered by the UPS display). The client wants to reduce down to using only one 6.3kVA unit. When dealing computer network equipment, what percent of rated load should I assume the equipment will draw? Is it unreasonable to suggest the UPS units should be able to supply the rated load from the combined nameplate info?

Thanks for any help or advice!

Sense...

 

[mpparent]

Are the UPS's in an N+1 configuration or a "capacity" configuration?

Mike

 

[rbulsara]

There is no rule so I don't have an answer.

But your dilemma is not unique so I am sharing some views. Typically the computer equipment mfr. do a very poor job of publishing or nameplating correct power consumption of their equipment. There is some sign of improvement lately, but still leaves much to desire.

Your case involves so small a UPS that to me its immaterial whether you have 2 or 1 -6.3kVA unit. Also if these are existing equipment, measure the loads of each equipment or panel and you should have a good idea.

Key question is what does the owner wants in the future, if he plans to grow.

For larger data centers or computer room rules of thumb are used or watts per sq. ft or extrapolated from existing data if available.

Also ever changing computer/server technology also makes it very difficult to create any trends or rules of thumb.

So a good judgement, experience with like work and a frank discussion with the owner and end user plays key role in final decision.