Load Calculation For A/C

[i.qasim]

Dear Engineers,
Thank you for the awesome forum.

I got some answers from the already posted threads. but I have this one to clearify.

Lets say,

I have a 10 Ton Package unit to install [3phase 380V] and supply power.
should my calculation look like this:

KW= 10*3.51
A=35.1/(1.732*380) [lets say p.f is 1]

A=53.3A

Now, is it okey to select Circuit breaker and Cable according to this value of 53.3 A,
say 63A with 4C 25 sq-mm.

Or I am missing things??

I went through the forum and looks like I am missing alot.

Thank you

 

[Mgraw]

I would get the specs from the manufacturer. A typical Trane 10 ton in 380v range would be 33-37 mca with a 40-45 mocp.

 

[i.qasim]

I would get the specs from the manufacturer. A typical Trane 10 ton in 380v range would be 33-37 mca with a 40-45 mocp.

thanks

sounds nice and simple

 

[topgone]

Dear Engineers,
Thank you for the awesome forum.

I got some answers from the already posted threads. but I have this one to clearify.

Lets say,

I have a 10 Ton Package unit to install [3phase 380V] and supply power.
should my calculation look like this:

KW= 10*3.51
A=35.1/(1.732*380) [lets say p.f is 1]

A=53.3A

Now, is it okey to select Circuit breaker and Cable according to this value of 53.3 A,
say 63A with 4C 25 sq-mm.

Or I am missing things??

I went through the forum and looks like I am missing alot.

Thank you

What you failed to understand on the above-posted calcs is that 10 tons of refrigeration is "heat" (10 x 12,000 BTU = 120,000 BTUs). The method used to cool a space is to "pump" out that amount of BTUs using an equipment that is made up of a refrigerant compressor and fans to transfer the heat. That said, you will have to compute for the pump + fans combo that will transfer 120,000 per hour--> you need to know how many watts per BTU your machine does. We call that as EER (energy efficiency ratio = kW input/ BTUs moved). Then you can compute for the needed electrical power based on that kW figure.

 

[Smart $]

What you failed to understand on the above-posted calcs is that 10 tons of refrigeration is "heat" (10 x 12,000 BTU = 120,000 BTUs). The method used to cool a space is to "pump" out that amount of BTUs using an equipment that is made up of a refrigerant compressor and fans to transfer the heat. That said, you will have to compute for the pump + fans combo that will transfer 120,000 per hour--> you need to know how many watts per BTU your machine does. We call that as EER (energy efficiency ratio = kW input/ BTUs moved). Then you can compute for the needed electrical power based on that kW figure.

I agree with all that... but it's still better to obtain MCA and MOCP, especially because that's what Code requires. :happyyes: