Air-Conditioning for UPS

[Ronald3]

Dear Expert,

A plant room size is 10m(L) x 8m(W) with 2 numbers of 2HP air-conditioners. In this room, 20 UPS with total power consumption of 40kVA were installed.

Our client would like to install 3 more UPS with total 6KVA. Is it necessary to install more air-conditioners for this room? Is there any typical calculations ?

Thanks for your help in advance !!

Ronald

 

[IRstuff]

Is this for school? Someone else posted a similar question with a similar problem with using HP as some sort of measure of A/C. Tons or BTUH or equivalent is needed.

TTFN

FAQ731-376

 

[ChrisConley]

If this isn't homework, you'll need to know the heat loss of the UPS. A straight conversion of kVA to kW would be an extremely conservative way to estimate heat gain.

 

[SAK9]

No fish for you but can teach you how to!

A UPS is about 90% efficient.Heat rejection from a 46 KVA will be about 4.6 KVA. This holds good if the UPS is serving equipment outside the room(for eg hospitals,labs etc)

If the UPS is serving equipment within the room,then total heat rejection will be 46KVA(for eg data centre.

 

[Ronald3]

Dear SAK9, ChrisConley & IRstuff,

Thank you very much for your advices.

Firstly, please forgive me for my electrical engineering education background. So, it would be trouble if I come across to the mechanical or HVAC subject sometimes....

For the question, I got the BTUH, which is 7,636 BTUH. The total KVA for the UPS is 46KVA and the heat rejection is about 4.6KVA. Room size is 10m(L) x 8m(W)

Is the air conditioner with 7,636 BTUH enough for the UPS ? and any typical calculations ?

Thanks for your help in advance.

Ronald

 

[ChrisConley]

kW = kVA * power factor

Power factor ~90% for computer equipment. With your background you might be able to do better.

kW (heat) = 4.6kVA * 90%

heat gain from UPS ~4.14 kW = 14126 Btu/hr

If you have 7,636 Btu/hr of cooling, I'd say you were low.

 

[IRstuff]

Electronics tend to need to run on the cooler side to maintain reliability and comfort of any person working in the room for any length of time.

Is the room very cool during hot days? If so, then you have on the order of about 2 tons of A/C, which is roughly one ton for the UPSs, and one ton for the room itself. With about a 13% increase in UPS load, it's about a 6.5% increase in total load. So, you need to have some feel for how cold the room can get during the hotest day. If there's ample excess capacity, then the additional load shouldn't have that big an impact.

TTFN

FAQ731-376

 

[Ronald3]

Problem solved, I would like to say thank you to ChrisConley, IRstuff and SAK9, thanks a lot.